JP6478812B2 - Printing device - Google Patents

Description

The present invention relates to a print apparatus having a platen for supporting the sheet.

  Patent Document 1 discloses an ink jet printing apparatus capable of performing so-called “marginless printing” in which an image is formed without providing a margin at an end of a sheet. This apparatus uses a suction platen that adsorbs a sheet by negative pressure.

JP 2006-021475 A

  In Patent Document 1, when performing borderless printing on the trailing edge of the sheet, the sheet is adsorbed to the adsorption portion of the platen. However, when borderless printing is performed on the leading edge of the sheet, the leading edge of the sheet has not yet reached the suction portion and is not sucked. For this reason, when the sheet is introduced, the lifting of the leading edge of the sheet cannot be suppressed, and the ink is landed while the sheet is lifted. As a result, there is a possibility that the image quality at the raised portion is deteriorated, or the sheet comes into contact with the print head and the sheet becomes dirty.

The present invention, floating or deflection suppressing such a sheet, and an object thereof is to provide a high-quality image that can obtain the print equipment in marginless printing.

The present invention includes a Ruhe head for discharging the ink, a sheet is a conveying means for conveying in a first direction, printing device Ru and a platen for supporting the sheet in front Kihe head position opposed to The platen includes a first support portion formed with a contact portion that contacts the sheet, a recess that is surrounded by the contact portion and does not contact the sheet, and a suction hole that sucks air from the recess . A first ink receiving portion that extends in a second direction intersecting the direction and is disposed upstream of the first support portion in the first direction and receives ink ejected from the head ; and extends in the second direction And a second ink receiving portion that is disposed downstream of the first support portion in the first direction and receives ink ejected from the head, and the contact portion extends in the second direction. Upstream contact portion and in the first direction A downstream contact portion disposed downstream from the upstream contact portion and extending in the second direction; and a side contact portion connecting the upstream contact portion and the downstream contact portion and extending in the first direction. The first support portion includes a recess having a first rib extending from the upstream contact portion in the first direction and spaced apart from the downstream contact portion, and an upstream contact portion extending from the downstream contact portion in the first direction. at least one of the second ribs spaced is characterized that you have provided.

  According to the present invention, it is possible to suppress sheet floating and bending and to obtain a high-quality image in borderless printing.

FIG. 2 is a perspective view illustrating an appearance of the printing apparatus. 1 is a perspective view illustrating an overall configuration of a printing apparatus main body. It is a vertical side view of a printing apparatus. It is a perspective view which shows a platen and its peripheral structure. It is a perspective view which shows the whole structure of a platen. It is an enlarged view which shows a part of platen. It is a vertical side view which shows a part of platen. It is a figure which shows the sheet | seat support part corresponding to the size of a sheet | seat. It is a perspective view which shows the state which has arrange | positioned the ink absorber to the ink discard groove | channel. It is a vertical side view which shows a part of platen. It is a vertical side view which shows a part of platen. It is a vertical side view which shows a part of platen. It is a vertical side view which shows a sheet | seat adsorption | suction mechanism. It is the perspective view which looked at the sheet adsorption mechanism from the bottom. FIG. 4 is a longitudinal side view of a first conveyance roller pair, a second conveyance roller pair, and a platen. FIG. 2 is a block diagram illustrating a control system configuration of a printing apparatus. It is a top view which shows the state which the front-end | tip of a sheet | seat passes on a sheet | seat support part. FIG. 6 is a plan view showing a position of a sheet immediately before printing is started. It is a top view which shows the state in which the intermediate part of the sheet | seat is printed. FIG. 10 is a plan view showing a state immediately before the trailing edge of the sheet starts printing. It is a top view which shows the state in which the rear-end part of a sheet | seat passes a sheet | seat support part.

  An embodiment of a printing apparatus according to the present invention will be described. Hereinafter, an example of a serial type inkjet printing apparatus that performs printing by reciprocating a print head capable of ejecting ink in a direction intersecting the sheet conveyance direction with respect to a sheet intermittently conveyed in a certain direction will be described. To do. The present invention is not limited to a serial type printing apparatus, but can be applied to a line printing apparatus that performs continuous printing using a long print head. The printing apparatus is not limited to a single-function printing apparatus, but can be applied to a multifunction printer having both a copy function and a facsimile function.

1. Overview of Apparatus FIG. 1 is a perspective view illustrating an appearance of a printing apparatus 1 according to an embodiment. A front side of the printing apparatus 1 is provided with a discharge tray 12 that supports printed sheets, and an operation unit 1a and a display unit 1b for performing various setting operations. Further, an upper surface cover 1c covering an internal structure such as a carriage described later is provided on the upper surface of the printing apparatus 1 so as to be openable and closable, and a sheet for feeding a sheet feeding device 40 described later is stacked on the rear surface. A feeding tray 40a is provided to be openable and closable. Although FIG. 1 shows a state in which the discharge tray 12 and the feeding tray 40a are closed, it is possible to open both trays 12 and 40a as shown in FIG.

  Here, the configuration of the printing apparatus main body 1A will be described with reference to FIGS. FIG. 2 is a perspective view showing an overall configuration of a printing apparatus main body 1A obtained by removing an exterior portion from the printing apparatus 1, and FIG. 3 is a longitudinal side view of the printing apparatus 1A shown in FIG.

  A feeding device 40 is provided on the back side of the printing apparatus main body 1A. The feeding device 40 separates the sheets one by one from the bundle of cut sheets (hereinafter simply referred to as “sheets”) stacked on the feeding tray 5 by the rotation of the feeding roller 6, and transport means such as the transport roller 7. To feed. The printing apparatus main body 1A is provided with a carriage 4 on which a print head 3 capable of ejecting ink is mounted. The carriage 4 is supported so as to be capable of reciprocating along a carriage guide shaft 41 and a carriage rail 42 provided along a direction (X direction) intersecting (orthogonal in the embodiment) with respect to the sheet conveyance direction (Y direction). Has been. The movement of the carriage 4 and the print head 3 along the X direction is also referred to as scanning in the following description. The X direction is the carriage movement direction and also the sheet width direction of the conveyed sheet. The Y direction is the sheet conveying direction.

  One sheet separated and fed by the feeding device 40 from a bundle of sheets stacked on the feeding tray 40a is printed by a first conveying roller pair (conveying means) composed of a conveying roller 7 and a pinch roller 8 by a print head. 3 is conveyed onto a platen 9 that supports the sheet opposite to the sheet 3. Here, the carriage 4 on which the print head 3 is mounted moves in the X direction, and ink is ejected from the print head 3 toward the sheet. A sheet detection sensor for detecting the end of the sheet is provided on one side surface of the carriage 4. Based on the detection output from the sheet detection sensor, the relative position between the sheet and the print head and the start of printing on the sheet are provided. Timing is determined.

  When printing for one scanning is performed on the sheet, the sheet is conveyed by a predetermined amount in the Y direction orthogonal to the X direction by the first conveying roller pair. By repeating the scanning of the print head 3 and the conveyance of the sheet, printing on the sheet is performed in a serial manner.

  The printed sheet 2 is discharged onto the discharge tray 12 by a second conveyance roller pair (conveying means) including a discharge roller 10 and a spur 11 disposed downstream of the platen 9 in the sheet conveyance direction (Y direction). Is done. The feeding device 40, the carriage guide shaft 41, the carriage rail 42, and the platen 9 are fixedly supported by the chassis 28 that forms the skeleton of the printing apparatus main body 1A. Further, other members including the above-described discharge tray 12, top cover 1c, feeding tray 40a, and the like are also supported by the chassis 28.

2. Next, the structure of the platen 9 will be described. FIG. 4 is a perspective view showing the platen 9 and its peripheral structure. As shown in FIGS. 4A and 4B, the platen 9 is provided between a first conveyance roller pair including a conveyance roller 7 and a pinch roller, and a second conveyance roller pair including a discharge roller 10 and a spur 11. Is arranged. The platen 9 supports a sheet conveyed by the first and second conveying roller pairs on a surface (back surface) opposite to the print surface.

2.1 Sheet Support Section FIG. 5 is a perspective view showing the overall configuration of the platen 9. The platen 9 is formed with a sheet support portion (support portion) 14 capable of supporting the back surface of the sheet while suppressing the floating and bending of the sheet in order to keep an appropriate distance between the discharge port surface of the print head 3 and the sheet. Yes. A plurality of sheet support portions 14 are formed along the longitudinal direction (X direction) of the platen 9.

  FIG. 6 is an enlarged view showing a part of the platen 9 shown in FIG. The sheet support portion 14 is formed in a rectangular frame shape by a convex portion. The sheet support surface 13 of the support portion 14 has a width of about several millimeters. An adsorption recess 17 is formed on the upper portion of the sheet support portion 14 to form a recess that is one step lower than the sheet support surface 13. A suction hole (suction part) 18 penetrating the platen 9 is formed on the bottom surface of the suction recess 17. The suction hole 18 communicates with a negative pressure generating means 19 described later. The negative pressure generated by the negative pressure generating means 19 is supplied to the suction recess 17 through the suction hole 18. The sheet passing through the sheet support surface 13 is sucked by the negative pressure supplied to the suction recess 17 and is sucked by the sheet support surface 13. As a result, the sheet is conveyed while being kept in a flat state without bending or floating, and the distance between the discharge port surface 3a of the print head 3 and the sheet 2 (the distance between the sheets) is set to an appropriate distance set in advance. Kept.

2.2 Ink discarding section In order to reliably perform so-called borderless printing in which no margin is provided at the periphery of the sheet and recording is performed on the entire sheet, it is necessary to eject ink beyond the edge of the sheet. Necessary. In addition, in the ink jet printing apparatus, so-called preliminary ejection, in which ink is ejected to the outside of the sheet immediately before the printing operation, is performed in order to stabilize the ink ejection performance of the print head 3. The ink ejected to the outside of such a sheet is received by an ink receiving portion formed on the platen 9. In this example, as an ink receiving portion, a front end ink discarding groove (first ink receiving portion) 31A for receiving ink discharged outside the front end of the sheet, and a rear end for receiving ink discharged outside the rear end of the sheet And an ink discarding groove (second ink receiving portion) 31B.

  FIG. 7 is a longitudinal side view showing a part of the platen 9, and shows a cross section of the leading-end ink discarding groove 31 </ b> A and the trailing-end ink discarding groove 31 </ b> B of the platen 9. As shown in the drawing, the front end ink discarding groove 31A extends in the X direction on the downstream side of the sheet support portion 14, and the rear end ink discard groove 31B is formed on the upstream side of the sheet support portion 14 in the X direction. It is long and thin. The leading-edge ink discarding groove 31 </ b> A is formed by a bottom surface 31 a lower than the sheet support surface 13, a downstream side wall surface 31 d of the sheet support portion 14, and a side wall surface 31 e of the downstream sheet support portion 33. The rear end ink discarding groove 31 </ b> B is formed by a bottom surface 31 a lower than the sheet support surface 13, an upstream side wall surface 31 c of the sheet support portion 14, and a side wall surface 31 b of the upstream side sheet support portion 32. The leading-end ink discarding groove 31A and the trailing-end ink discarding groove 31B are formed in such a volume that the ink does not overflow when the ink ejected from the print head 3 is received.

  On the other hand, in order to reliably perform borderless printing on the left and right edges (sheet side edges) of the sheet in the sheet width direction, when the print head 3 ejects ink while scanning in the X direction, it is more than the left and right edges of the sheet. It is necessary to eject ink to the outside. In addition, even when the sheet width of the sheet to be used is changed, the left and right end ink strikes that match the width of each sheet are placed on the platen so that the ink ejected outside the sheet side end can be received. A discard groove (third ink receiving portion) 34 is provided (see FIG. 8).

  As the size of the sheet for borderless printing, a standard size sheet such as L size, 2L size, postcard, A4, letter, A3, legal, A2 is mainly used. Therefore, in accordance with these sheet sizes, a plurality of ink discard grooves 34 are arranged at the left and right sheet edge positions of each sheet. As described above, the front-side ink discarding groove 31A, the rear-end ink discarding groove 31B, and the left and right-end ink discarding grooves 34 are formed in a lattice pattern on the surface side of the platen 9. The sheet support portion 14 is surrounded by these grooves.

  The arrangement of the sheet support portion 14 is determined according to the print position standard. In the present embodiment, a so-called center reference sheet supply in which the reference of the print position is set at the center of the width of the print sheet is employed. With the center reference, the sheet is conveyed so that the center of the sheet width (print width) and the center of the platen 9 in the width direction coincide with each other in various sheet widths. Accordingly, the sheet supporting portions 14 are arranged symmetrically so that the left and right end ink discarding grooves 34 are formed at positions that are symmetric with respect to the center position of the width of the platen 9 in the X direction. When performing borderless printing, the ink discard groove 34 for the left and right edges is positioned on the inside by about 2 mm from the left and right edges of the sheet, and the other side is approximately 5 mm on the outside from the edges of the sheet. It is preferable to be located only outside. Accordingly, the width of the edgeless groove and the position of the sheet support portion are set so as to satisfy the positional relationship as described above for various types of standard sheets. Note that instead of the center reference, sheets having various sheet widths may be used as a one-side reference that aligns the left and right reference positions.

  FIG. 8 is a diagram illustrating a sheet support portion corresponding to A4 size sheets and A3 size sheets, as an example. Since the center reference is adopted as described above, the center of the sheet always passes through one center reference 2d set on the platen 9 even if the sheets have different sizes. When an A4 size sheet is conveyed along its longitudinal direction, the end of the sheet passes through a position 105 mm away from the center reference 2d of the platen 9 in the X direction. For this reason, the sheet support portion 14 is arranged so that the ink discarding grooves 34 for the left and right ends are formed in the range from 103 mm to 110 mm from the center reference 2d. When an A3 size sheet is conveyed along its longitudinal direction, the end of the sheet passes through a position 148.5 mm away from the center reference 2d of the platen 9 in the X direction. Accordingly, the sheet supporting portion 14 is arranged so that the ink discarding grooves 34 for the left and right ends are formed in the range of the center reference 2d to 146.5 mm to 153.5 mm. In the case of one-side reference instead of the center reference, the number of ink discard grooves 34 for the left and right ends is halved, and the distance from the reference position also changes.

  In order to correspond to a plurality of types of sheets having different sheet widths (sheet sizes in the X direction), five types of sheet support portions 14 (first to sixth sheet support portions (14A to 14F) having different sizes are formed. Of these, the first sheet support portion 14A to the fifth sheet support portion 14E are formed with suction recesses 17 having a relatively large area, The suction hole 18 is formed as described above, but the suction hole 18 is omitted in the smallest fifth sheet support portion 14F because the area of the suction recess 17 is small. The sheet support portion 14F corresponds to the size sheet and the half-cut width size sheet, and the suction hole 18 is omitted in the suction recess 17 of each sheet support portion 14F.

  Further, the first, second, and third sheet support portions 14A, 14B, and 14C having a relatively large frame shape have the same height as the sheet support surface 13 in order to prevent the sheet from falling into the suction concave portion 17. The intermediate rib 14r having the shape is formed in a direction (Y direction) orthogonal to the X direction. Here, three intermediate ribs 14r are formed on the first sheet support portion 14A, and two 14r are formed on the second sheet support portion 14B and the third sheet support portion 14C, respectively. Forms a support surface that is continuous with the sheet support surface 13 having a frame shape. However, the intermediate rib 14r is not formed on the fifth and sixth sheet support portions 14E and 14F. Note that the number of suction holes 18, the diameter of the suction holes, the number of intermediate ribs, and the like are preferably set as appropriate according to the size of the sheet support portion 14 and the suction recess portion determined by the corresponding sheet size and the like.

  Assuming that borderless printing is performed on the four sides of the cut sheet in this way, the sheet support portion 14 of the platen 9 has the leading and trailing edge ink discarding grooves 31A and 31B, and the left and right edge ink discarding grooves of the sheet. 34, and is in an isolated form. In addition, in order to suppress the occurrence of mist due to the rebound at the time of ink landing and the leakage of the discarded ink in each of the ink discard grooves 31A, 31B, and 34, as shown in FIGS. Is arranged. The ink absorber 35 is preferably composed of a single sponge-like sheet such as urethane foam. Further, the upper surface of the ink absorber 35 is locked by a plurality of locking claws 38 (see FIG. 8), and is prevented from falling off the platen 9.

  Further, the platen 9 is provided with a sheet support portion 14 including the suction holes 18 and an outer peripheral wall 20 surrounding the ink discarding groove 31, and a casing (platen casing) is formed by the outer peripheral wall 20. . A waste ink discharge port communicating with each ink discarding groove 31A, 31B is provided on the side of the outer peripheral wall 20, and the waste ink discarded into each ink discarding groove 31A, 31B is waste ink. It is discharged from the discharge port 30 to the outside of the platen 9.

2.3 Air Inflow Path FIG. 10 is a longitudinal side view showing the air inflow path provided in the upstream and downstream side seat support portions. An upstream sheet support portion 32 that supports the sheet transported from the transport roller 7 from the back surface is formed further upstream of the ink discard groove 31B for the rear end of the platen 9. Further, a downstream sheet support portion 33 that supports the sheet conveyed by the discharge roller 10 from the back surface is formed further downstream than the ink discard groove 31A for the front end of the platen 9. Each of the upstream sheet support portion 32 and the downstream sheet support portion 33 is formed by a rib-like convex portion extending along the sheet conveyance direction (Y direction), as shown in FIG. , A plurality of them are arranged in the X direction at regular intervals.

  Further, the upstream sheet support part 32 and the downstream sheet support part 33 are formed so that the positions of the tops thereof are the same height as the sheet support surface (contact part) 13 of the sheet support part 14 described above. The upstream sheet support portion 32 and the downstream sheet support portion 33 prevent the sheet 2 from dropping or getting caught when the leading end or the trailing end of the sheet 2 passes through the sheet supporting portion 14 or each roller. Fulfills the function.

  On the other hand, adjacent ones of the plurality of upstream sheet support portions 32 are connected to each other by a connection seating surface 37 (see FIGS. 6 and 10), and a sheet passing sheet and the connection seating surface 37 are connected to each other. A gap is formed between them (see FIG. 10). Similarly, the downstream seat support portions 32 are connected to each other by the connection seat surface 37, and a gap is formed between the seat 2 supported by the downstream seat support portion 32 and the connection seat surface 37. . For this reason, an air flow path for introducing fresh air from the outside of the platen 9 to the ink discarding groove 31 is formed as indicated by a broken line arrow A in FIG. Further, a notch 39 is formed in a part of the connection seat surface 37 as shown in FIG. 6, so that air can flow in the direction perpendicular to the back surface of the seat as shown by the broken line arrow B. A flow path is also formed. In general, since the conveying roller 7 is often a cylindrical roller whose entire surface is covered with rubber or coating particles, a portion constituting the sheet 2 to be conveyed, the conveying roller 7 and the connection seating surface 37 of the platen 9. It is easy to form a closed space. However, by providing the air inflow cutout 39, a gap is formed between the sheet 2 and the upstream sheet support 32, and faces the ink discarding grooves 31 A, 31 B, 34 of the platen 9. Thus, it becomes possible to supply more fresh air. Therefore, even if the ink mist generated by the discharge operation of the print head floats and diffuses in the ink discarding groove, the concentration of this ink mist is diluted by fresh air flowing in from the outside, The amount of ink mist that adheres is reduced.

2.4 Positional Relationship between Print Head and Sheet Supporting Unit FIG. 11 is a diagram showing a positional relationship between the ejection port of the printhead 3 and the sheet supporting unit 14 at the start of the printing operation. FIG. 12 is a diagram showing a positional relationship among the rear end of the sheet 2, the discharge port of the print head, and the sheet support portion 14 at the end of the printing operation.

  When starting the printing operation, as shown in FIG. 11, the sheet 2 is conveyed to a position that completely covers the sheet support surface 13. When the sheet support surface 13 is completely covered with the sheet 2, a stable negative pressure can be generated in the suction recess 17. Further, the sheet is conveyed to a position that slightly protrudes from the sheet support surface 13 in order to allow the sheet to be adsorbed even if the position of the fed sheet 2 is slightly shifted.

  In the serial type printing apparatus, the length of the ejection port array formed by arranging a plurality of ejection ports is set as follows. That is, as shown in FIGS. 11 and 12, the ejection port array 3b of the print head 3 is formed within a range that completely includes the sheet support portion 14 in the sheet conveyance direction (Y direction). Accordingly, the most upstream end discharge port 3c of the discharge port array 3b is located outside (upstream) of the upstream end 14a of the sheet support portion 14, and the most downstream end discharge port 3d is outside of the downstream end 14b of the sheet support portion 14 ( It is located on the downstream side.

  Further, in marginless printing in which an image is formed on the entire surface of the sheet 2 without leaving margins at the front and rear ends of the sheet 2, the sheet is conveyed so that the front end 2 a or the rear end 2 b of the sheet 2 slightly protrudes from the sheet support portion 14. Therefore, at the time of recording on the leading edge 2a of the sheet 2 (FIG. 11), it is necessary that the most downstream discharge port 3d of the print head 3 is positioned slightly downstream from the leading edge 2a of the sheet 2. Further, at the time of recording on the rear end 2b of the sheet 2 (FIG. 12), the most upstream discharge port 3c of the print head 3 needs to be positioned slightly upstream from the rear end of the sheet as shown in FIG. It is. Strictly speaking, it is preferable to set the protrusion amount L in consideration of the stop accuracy of the leading or trailing end position of the sheet and the dimension that does not generate a margin after considering the dimensional tolerance. A protruding amount L is set.

  In summary, it is necessary to set the relationship between the sheet support portion 14 and the discharge port of the print head as follows. That is, the upstream end 14 a of the sheet support portion 14 is disposed downstream of the most upstream discharge port 3 c in the sheet conveying direction, and the downstream end 14 b of the sheet support portion 14 is upstream of the most downstream discharge port 3 d of the print head 3. Place on the side. According to this, it is possible to eject ink to a range where the printing range for ejecting ink slightly protrudes from the leading edge and the trailing edge of the sheet 2, and it is possible to reliably perform borderless printing on the leading edge and the trailing edge of the sheet 2. Can be done.

  Further, when borderless printing is performed at the end portions (left and right ends) in the width direction of the sheet, the sheet is supported by a sheet support portion disposed in a range slightly smaller than the sheet size to be printed. Then, the scanning range of the print head 3 is determined so that the ink is ejected to a range slightly protruding outward (side) from the sheet. Thereby, borderless printing can be performed also on the left and right edges of the sheet.

3. Sheet Adsorption Mechanism FIG. 13 is a longitudinal side view showing a sheet adsorption mechanism provided in the printing apparatus, and FIG. 14 is a perspective view of the sheet adsorption mechanism as seen from the bottom. The sheet suction mechanism includes a platen 9, a duct 27 that communicates with a suction hole 18 formed in the platen 9, and a negative pressure generating unit that communicates with the duct 27.

  Immediately below the platen housing formed by the outer peripheral wall 20 of the platen 9, a cover member 23 having a first opening 23a on the upper surface and a base member 24 having a second opening 24a on the lower surface are configured. A duct 27 having a hollow inside is provided. The upper surface of the cover member 23 is engaged with the bottom side of the outer peripheral wall 20 of the platen 9 so that the first opening 23a is included. The second opening 24a provided on the lower surface of the base member 24 is engaged with the suction port 19a of the suction fan 19 which is a negative pressure generating means. As a result, an intake flow path 36 extending from the suction hole 18 of the platen 9 to the suction fan 19 is formed. The intake flow path 36 is formed in a duct 27 composed of a first negative pressure chamber 22 corresponding to a space in the platen casing formed by the outer peripheral wall 20 of the platen 9, and the base member 24 and the cover member 23. The second negative pressure chamber 25 is configured. The base member 24 forming the duct 27 is fixed to the chassis 28.

  The first negative pressure chamber 22 corresponds to each of the plurality of sheet support portions 14 and is an independent small space partitioned into a plurality in the sheet width direction. FIG. 13 illustrates one small space. The first negative pressure chamber 22 and the second negative pressure chamber 25 are partitioned by a cover member 23, and the common second negative pressure chamber 25 is divided into a plurality of first negative pressure chambers 22. It communicates through the small space opening 23a.

  Air leaks to the engaging portion between the upper surface of the cover member 23 and the bottom of the outer peripheral wall 20 of the platen 9, and the engaging portion between the second opening 24a of the base member 24 and the suction port 19a of the suction fan 19, respectively. A seal member 26 for preventing the above is disposed. The seal member 26 is preferably made of foamed rubber or the like made of EPDM that is soft and has high sealing properties so that the platen 9 and the cover member 23 are not deformed by the repulsive force when compressed. By interposing the seal member 26 between the members, it is possible to suppress the drive vibration of the suction fan 19 from being transmitted to the platen 9 while maintaining the sealing property between the members, and to the printing operation. The influence of can be suppressed.

  Further, since the waste ink discharge port 30 of the platen 9 is provided on the outer peripheral wall 20 of the platen 9, the duct 27 disposed immediately below the platen 9 is obstructed by the arrangement of the waste ink discharge port 30. The space directly under the platen 9 can be occupied. As a result, the second negative pressure chamber 25 of the duct 27 can have a sufficient size to stabilize the negative pressure generated by the rotation of the suction fan 19, and the degree of freedom in design is greatly improved. To do.

  The suction fan 19 as the negative pressure generating means is preferably a sirocco fan having a high suction efficiency. The suction fan 19 can adjust the suction air volume by PWM control. By making the air volume variable depending on the type of sheet, the state of the sheet, and the use atmosphere environment, the adsorptivity of the sheet can be adjusted.

  In the above configuration, by rotating the suction fan 19 and discharging the air in the duct 27, the entire intake passage 36 is in a negative pressure state, and air can be sucked from the suction hole 18 communicating with the duct 27. it can.

  The platen 9 is manufactured as one part by a resin mold. The plurality of sheet support portions 14, the upstream sheet support portion 32, the downstream sheet support portion 33, the plurality of first negative pressure chambers 22, and the ink receiving portions (first to third ink receiving portions) are all included in the platen 9. It is formed in one resin mold part that constitutes. This simplifies the manufacturing of the printing apparatus and improves the relative positional accuracy of the functional units.

4). Sheet Offset FIG. 15 is a vertical side view of the first conveying roller pair, the second conveying roller pair, and the platen described above. The conveying roller 7 and the pinch roller 8 forming the first conveying roller pair are arranged so that the conveying roller nip tangent L1 passing through the contact point between both rollers intersects with the sheet supporting surface 32a of the upstream sheet supporting portion 32. By arranging the first conveying roller pair in this way, it is possible to reliably bring the leading edge of the sheet conveyed to the print start position into contact with the sheet supporting surface 13 of the sheet supporting unit 14. As a result, the negative pressure can be efficiently generated, and the sheet can be adsorbed more reliably.

  Similarly, the discharge roller 10 and the spur 11 that form the second conveying roller pair are arranged so that the discharge roller nip tangent L2 that passes through the contact between them intersects the sheet support surface 33a of the downstream sheet support portion 33. . By arranging the second conveying roller pair in this way, it becomes possible to bring the trailing edge of the sheet into contact with the sheet support surface 13 to the end even after printing is completed, and the posture of the efficient suction state is made longer. Can be held.

  As described above, according to the present embodiment, even at the leading edge and the trailing edge of the sheet, it can be efficiently adsorbed to the sheet support surface 13 of the platen, and the sheet is spread over the entire region from the leading edge to the trailing edge of the sheet. Levitation can be reduced.

5. Control Circuit FIG. 16 is a block diagram showing a schematic configuration of a control system of the printing apparatus 1 in this embodiment. The CPU 101 is connected to a head drive circuit 102 that controls ink ejection of the print head 3. Further, the CPU 101 is connected to a motor drive circuit 103 for controlling motors (carriage motor 104, transport roller motor 105, feed roller motor 106, pump drive motor 107, suction fan 19, etc.) that operate each mechanism. .

  The suction fan 19 is PWM-controlled by a motor drive circuit, and can adjust the air volume to adjust the suction negative pressure of the sheet suction portion. Changing the air volume according to the type of sheet, the state of the sheet, and the conditions of the atmospheric environment is an effective means for adjusting the sheet transportability. It is also possible to change the air volume according to the conditions of the position of the carriage 4 and the conveying position of the sheet.

6). Printing Operation FIG. 17 is a plan view showing a state in which the leading edge of the sheet 2 passes over the sheet support portion 14 by the feeding operation by the feeding device 40.
The sheets 2 stacked on the feeding tray 5 are fed to the conveying roller 7 by the aforementioned feeding device 40 and further conveyed to the platen 9 by the conveying roller 7. Here, the suction fan 19 is activated while the sheet 2 is being fed, and a predetermined negative pressure is generated in the duct 27 communicating with the suction hole 18 of the platen 9. The strength of the negative pressure is controlled according to the conditions of the sheet type, state, and atmospheric environment. It is preferable to generate a strong negative pressure (suction pressure) when using a thick paper, a paper with a large curl, or when the humidity is low. This negative pressure is controlled by the motor drive circuit 103 that controls the drive of the suction fan 19. Various control methods can be applied. For example, PWM control or the like can be used.

  Prior to the start of the printing operation, the sheet 2 is conveyed to the position shown in FIG. That is, after the leading edge 2a of the sheet passes the ink discard groove 31 of the upstream sheet support portion 32 and reaches the sheet support portion 14, the sheet is further conveyed to a position protruding slightly from the downstream end 14b, and the conveyance operation is temporarily stopped. The At this point, the sheet 2 is attracted to the sheet support surface 13. During the conveying operation until this state is reached, a negative pressure is generated in the suction recess 17, so that the leading edge 2 a of the sheet 2 is conveyed while being sucked toward the support surface 13. Accordingly, the sheet 2 can be prevented from rising of the leading edge 2a until it is conveyed to the position shown in FIG. FIG. 18 shows the position of the sheet immediately before printing is started. In addition, until the sheet 2 covers the sheet support surface, a sufficient suction force cannot be obtained for the sheet 2, but since the sheet 2 is transported in a state in which the leading edge 2a is suppressed, the cueing position Is smoothly conveyed. An inclined surface 13 a that guides the leading edge 2 a of the sheet to the sheet support surface 13 is formed at the upstream end of the sheet support portion 14. Therefore, even when the leading edge 2a of the sheet drops downward when passing through the ink discarding groove 31B, the leading edge 2a of the sheet is guided to the sheet supporting surface 13 by contact with the inclined surface 13a. It can pass through the discard groove 31B smoothly.

  From the state where the aforementioned sheet is fed to the cueing position, the print head 3 reciprocally scans according to the image data to start printing. When performing borderless printing on the leading edge of the sheet, an image is printed on the sheet 2 and ink is ejected to an area outside (downstream) the leading edge of the sheet 2. The ink ejected to the area outside the sheet 2 is discarded by the ink absorber 35 in the rear end ink discarding groove 31 located on the downstream side of the sheet support portion 14. After completion of borderless printing on the leading edge 2 a of the sheet 2, printing is continued while repeating conveyance of the sheet by the conveyance roller 7 and the discharge roller 10 and reciprocating scanning of the print head 3.

  FIG. 19 is a diagram illustrating a state in which an intermediate portion of the sheet 2 is printed. When performing borderless printing on the left and right edges of the sheet, ink is ejected onto the sheet 2 and ink is also ejected to areas outside the left and right edges of the sheet 2. The platen 9 is also formed with left and right end ink discarding grooves 34 corresponding to the positions of the left and right ends of the sheet 2, and the ink ejected outside the left and right ends of the sheet 2 is outside the left and right ends of the sheet 2. The ink absorber 35 in the left and right end ink discard grooves 34 is discarded. Since the ink mist generated at this time is diluted by fresh air introduced from the air inflow passages provided upstream and downstream of the platen, adhesion of the ink mist to the back surface of the sheet is reduced.

  When printing is continued and the trailing edge of the sheet 2 passes between the first conveyance roller pair (conveyance roller 7 and pinch roller 8), the sheet is then conveyed by the second conveyance roller pair (discharge roller 10 and spur 11). 2 is carried. As shown in FIG. 20, when the rear end 2b of the sheet 2 is conveyed to a position protruding slightly upstream from the sheet support portion 14, borderless printing on the rear end 2b of the sheet 2 is performed. Here, ink is ejected onto the sheet 2 as well as borderless printing on the leading edge 2a of the sheet 2, and ink is also ejected to an area outside (upstream) from the rear end 2b of the sheet 2. The ink ejected to the area outside the rear end 2b of the sheet 2 is discarded by the ink absorber 35 (sponge) in the rear end ink discard groove 31B located on the upstream side of the sheet support portion 14. In this manner, the printing on the rear end 2b of the sheet 2 is also completed in a state where the sheet 2 is attracted to the sheet support surface 13.

  As described above, since the sheet 2 is always on the sheet support surface 13 of the sheet support part 14 from the start to the end of printing, the sheet 2 is always supported by introducing an appropriate negative pressure to the suction recess 17. Printing can be performed while adsorbed on the surface 13. For this reason, the sheet-to-sheet distance H (see FIG. 12) between the print head and the sheet can be maintained at a predetermined appropriate distance, and an image can be printed accurately. In addition, sheet contamination due to ink mist adhesion is reduced.

  FIG. 21 is a plan view showing a state in which the rear end portion of the sheet passes through the sheet support portion. After the printing is completed, the sheet 2 is conveyed by the second conveyance roller pair. At this time, the rear end 2 b of the sheet 2 is discharged to the discharge tray 12 through the front end ink discarding groove 31 B while being supported by the downstream sheet support portion 33.

  The above steps are the same as for borderless printing except that ink is not discharged to the outside of the sheet, even in the case of printing with margins that provide margins around the image on the sheet. Can be done.

  Further, during printing, if the level of the negative pressure generated by the suction fan 19 and the switching of driving / stopping of the suction fan 19 are controlled according to the printing conditions, an appropriate suction force is always applied to the sheet. Is possible.

  According to the embodiment that has been described above, it is possible to perform printing without a four-sided border on a cut sheet. Further, it is possible to perform printing while suppressing sheet floating and bending, and maintaining an appropriate distance between the print head and the sheet, and a high-quality image can be obtained in borderless printing.

2 Sheet 3 Print head 9 Platen 13 Sheet support part (contact part)
14 Seat support (support)
17 Adsorption recess (recess)
18 Suction hole (suction part)
31A End ink discard groove (first ink receiving portion)
31B a second ink receiving portion;
34 Ink discard grooves for left and right ends (third ink receiving portion)
35 Ink absorber

Claims (15)

And Ruhe head for discharging the ink, a sheet is a conveying means for conveying in a first direction, printing device Ru and a platen for supporting the sheet in front Kihe head facing position,
The platen is
A first support part formed with a contact part that comes into contact with the sheet, a recess surrounded by the contact part and not in contact with the sheet, and a suction hole that sucks air from the recess;
A first ink receiving portion that extends in a second direction intersecting the first direction and is arranged upstream of the first support portion in the first direction and receives ink ejected from the head ;
A second ink receiving portion that extends in the second direction and is disposed downstream of the first support portion in the first direction and receives ink ejected from the head ;
The contact portion includes an upstream contact portion extending in the second direction, a downstream contact portion disposed downstream of the upstream contact portion in the first direction and extending in the second direction, and the upstream contact portion. A side contact portion connecting the downstream contact portion and extending in the first direction,
The concave portion of the first support portion includes a first rib extending from the upstream contact portion in the first direction and separated from the downstream contact portion, and extending from the downstream contact portion in the first direction and separated from the upstream contact portion. printing device at least one of the second rib is characterized that you have provided. An upstream support portion that is disposed upstream of the first ink receiving portion in the first direction and supports the sheet; and a downstream support portion that is disposed downstream of the second ink receiving portion in the first direction and supports the sheet; printing apparatus as claimed in 請 Motomeko 1 you wherein Rukoto equipped with. A plurality of the first support portions are arranged in the second direction;
The platen is disposed between the first supporting portion adjacent extending in the first direction, it wherein a third ink receiving portion for receiving the ink discharged from the head is provided printing apparatus as claimed in 請 Motomeko 1 or 2. Wherein the first and the third ink receiving portion and Lee ink receiving portion and the second i ink receiving unit, billed not absorber is arranged to absorb ink ejected from the head you characterized Rukoto Item 4. The printing apparatus according to Item 3. An upstream end portion in the first direction of the first support portion, any one of the 請 Motomeko 1 you, characterized in that the inclined surface for guiding the sheet to the upstream contact portion is formed 4 The printing apparatus as described in. Said recess, said first rib, 5 the suction holes arranged, from 請 Motomeko 1 you wherein it has been found provided between the first rib and the downstream contact portion The printing apparatus according to any one of the above. Said recess, said second rib, said suction holes disposed between the second rib and the upstream contact portion, from 請 Motomeko 1 you wherein it has been found provided 6 The printing apparatus according to any one of the above. It said first rib and said second rib, printing apparatus as claimed in any one of 請 Motomeko 1-7 you wherein same height der Rukoto and the contact portion. The head has an ejection port array in which ejection ports for ejecting ink are arranged in the first direction;
The upstream end portion of the first support portion in the first direction is arranged downstream of the upstream end portion of the discharge port array, and the downstream end portion of the first support portion in the first direction is the ejection opening array printing apparatus as claimed in any one of 請 Motomeko 1 to 8 you wherein Rukoto disposed upstream from the downstream end of the. And the first support portion and the first ink receiving unit and the second ink receiving portion, 請 Motomeko 1 that you have been formed by aggregating the one resin molded part constituting the platen you wherein The printing apparatus according to any one of 1 to 9. Wherein the recess of the first support portion, the printing apparatus according to any one of the first rib and said second rib 請 Motomeko 1 to 10 both you characterized that you have provided for. The platen further includes a second support portion in which the contact portion and the recess are formed, and a length in the second direction is smaller than the first support portion,
Wherein the recess of the second supporting portion, said first rib and said second rib is not provided, the print device according to 請 Motomeko 11 you characterized in that said suction holes are provided. The platen further includes a third support portion in which the contact portion and the recess are formed, and the length in the second direction is smaller than the second support portion,
Wherein the recess of the third supporting part, printing apparatus as claimed in billed to claim 1 2 you, characterized in that not any provided of the first rib and the second rib and the suction holes. In the platen, the first support portion, the second support portion, and the third support portion are selectively arranged in the second direction so as to correspond to the width of the sheet in the second direction. printing apparatus as claimed in billed to claim 13 shall be the features. Printing apparatus according to any one of said further comprising Rukoto a carriage head was mounted for scanning in the second direction from 請 Motomeko 1 shall be the feature 14.