JP2019104254A - Printing device and control method of the same - Google Patents

Abstract

To reliably perform borderless printing on sheets of various sizes.SOLUTION: A printer device 1 comprises: a print head 3 for discharging ink; conveying means 7 for conveying a sheet in a first direction; a platen 9 disposed at a position facing the print head, for supporting the sheet conveyed by the conveying means 7; and suction means 19. The platen has: a plurality of support parts 14, each provided with a support face 13 provided along a second direction crossing the first direction and in contact with the sheet, a recess 17 surrounded by the support face and not in contact with the sheet, and a suction hole 18 provided in the recess and connected to the suction means 19; and an on-off valve 80 for opening and closing communication between the suction hole and the suction means. An end of the sheet is detected by detection means, and the opening and closing of the on-off valve is controlled by control means 101 based on a detection result.SELECTED DRAWING: Figure 11

Description

  The present invention relates to an inkjet printing apparatus.

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

JP, 2006-021475, A

  In Patent Document 1, when performing marginless printing on the rear end of the sheet, the sheet is adsorbed to the adsorption portion of the platen. However, when performing borderless printing on the front end of the sheet, the front end of the sheet has not yet reached the suction portion and has not been adsorbed. Therefore, when the sheet is introduced, it is not possible to suppress the floating of the front end of the sheet, and the ink lands in a state where the sheet is floating. As a result, the image quality in the raised portion may be degraded, or the sheet may come into contact with the print head to soil the sheet. In addition, the ink thrown away outside the edge of the sheet during borderless printing may float as misty ink mist and adhere to the back of the sheet.

  An object of the present invention is to provide a printing apparatus capable of reliably performing borderless printing on sheets of various sizes.

  According to an embodiment of the present invention for solving the above problems, there is provided a print head for discharging ink, a transport means for transporting a sheet in a first direction, and a sheet disposed at a position facing the print head and transported by the transport means. And a suction unit for supporting the sheet, the platen being provided along a second direction crossing the first direction and being in contact with the sheet, being surrounded by the sheet, and being in contact with the sheet And a plurality of support portions provided with the recess and the suction hole provided in the recess and connected to the suction means, and an open / close valve for opening and closing the communication between the suction hole and the suction means. The printing apparatus is characterized by further comprising: detection means capable of detecting an end portion of the sheet; and control means for controlling the opening and closing of the on-off valve based on the detection result of the detection means.

  According to the present invention, it is possible to reliably perform borderless printing on sheets of various sizes.

FIG. 1 is a perspective view showing an overall configuration of a printing apparatus. FIG. 2 is a longitudinal side view of the printing apparatus. FIG. 6 is a perspective view of the platen as viewed obliquely from above. It is an expansion perspective view showing a part of platen. It is a vertical side view of a platen. It is a vertical side view which shows an air flow path. It is a perspective view which shows the internal structure of a platen. It is an expansion perspective view of the on-off valve provided in the platen. It is a perspective view which shows the cam which drives an on-off valve. It is a perspective view which shows the drive mechanism of a cam. It is a block diagram showing control system composition. It is a flowchart showing a control operation It is a partial cross section perspective view which shows the positional relationship of a sheet | seat and a sheet | seat support part. FIG. 5 is a plan view showing the positional relationship between a sheet being printed and a platen. It is a flow chart which shows control operation in a 2nd embodiment.

  An embodiment of a printing apparatus according to the present invention will be described. Hereinafter, a serial type inkjet printing apparatus (hereinafter referred to as a printing apparatus) which performs printing by reciprocating a print head capable of ejecting ink in a direction intersecting the sheet conveyance direction with respect to the sheet intermittently conveyed in a predetermined direction ) Will be described as an example. The present invention is applicable not only to serial type printing apparatuses, but also to line printing apparatuses that print continuously using a long print head. The printing apparatus is not limited to a single-function printing apparatus, and can be applied to a multi-function printer having a copy function, a facsimile function, and the like.

  The configuration of the printing apparatus 1 will be described. FIG. 1 is a perspective view showing the entire configuration of the printing apparatus 1, and FIG. 2 is a longitudinal sectional side view of the printing apparatus 1 shown in FIG. A feeding device 40 is provided on the back side of the printing device 1. 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 and conveys the conveying roller 7 or the like. Feed to. Further, the printing apparatus 1 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) orthogonal (in the embodiment, orthogonal) to the sheet conveyance direction (Y direction). It is done. The X direction is the moving direction of the carriage and also the sheet width direction of the sheet to be conveyed. The Y direction is the sheet conveyance direction.

  A single sheet separated and fed by the feeding device 40 from the sheet bundle stacked on the feeding tray 5 is transferred to the print head by the first conveyance roller pair (conveying means) including the conveyance roller 7 and the pinch roller 8. The sheet is conveyed on a platen 9 that supports the sheet at a position facing the sheet 3. Here, the carriage 4 on which the print head 3 is mounted moves in the X direction, and the print head 3 discharges the ink toward the sheet. A carriage sensor is provided on one side of the carriage 4 to detect the end of the sheet, and based on the detection output from the carriage sensor, the sheet size, the relative position between the sheet and the print head 3, and printing on the sheet The start timing and the like are determined.

  When printing for one scan is performed on the sheet, the sheet is transported by a predetermined amount in the Y direction by the first transport roller pair. Printing on the sheet is performed by the serial method by repeating the movement of the print head 3 and the conveyance of the sheet.

  The sheet 2 on which printing has been completed is placed on the discharge tray 12 by the second conveyance roller pair (conveyance means), which is disposed downstream of the platen 9 in the sheet conveyance direction (Y direction), and includes the ejection roller 10 and the spur 11. Exhausted.

1.1 Platen Next, the structure of the platen 9 will be described. As shown in FIGS. 2 and 5, the platen 9 is disposed between a first conveying roller pair consisting of a conveying roller 7 and a pinch roller and a second conveying roller pair consisting of a discharge roller 10 and a spur 11 ing. The platen 9 is provided at a position facing the discharge port formation surface 3 a of the print head 3 in which discharge ports for discharging ink are arranged, and the sheet 2 transported by the first and second transport roller pairs is a discharge port. It supports the surface (rear surface) opposite to the printing surface opposite to the forming surface 3a. In FIG. 5, 3b represents a discharge port array formed on the discharge port forming surface 3a, 3c represents a discharge port positioned most upstream in the discharge port array, and 3d represents a discharge port positioned most downstream in the discharge port array. The exits are shown respectively.

  FIG. 3 is a perspective view of the platen shown in FIG. 1 as viewed obliquely from above. In FIG. 3, in order to maintain an appropriate distance between the discharge port forming surface 3 a of the print head 3 and the sheet 2, the sheet support portion 14 capable of supporting the back surface of the sheet while suppressing floating and bending of the sheet 2. It is formed. The sheet support portion 14 is configured to be divided into a plurality of regions along the longitudinal direction (X direction) of the platen 9 corresponding to a plurality of types of sheet width sizes.

  Specifically, the sheet support portion 14 is provided so as not to be positioned within a range of about 2 mm from the side edge of each of the plurality of standard size sheets during conveyance. The platen 9 of this embodiment corresponds to the sheet width of sheets such as L size, KG, 2 L size, six sections, Letter, A4, quarter sections, A3, A3 nobi, half section, A2, A2 nobi, 17 inches, etc. The arrangement and shape of the sheet support portion 14 are determined.

  Also, the arrangement of the sheet support portion 14 needs to be determined according to the reference of the print position. In the present embodiment, so-called sheet feeding based on center reference is employed in which the reference of the print position is set at the center of the sheet width. At the center reference, the sheet is conveyed such that the center of the sheet width (print width) and the center in the width direction of the platen 9 coincide with each other in any of various sheet widths. Therefore, the sheet support portion 14 is disposed at a position symmetrical with respect to the center position of the width of the platen 9 in the X direction. It should be noted that not only the center reference but also a sheet of various sheet widths may be used as a one-side reference that aligns either left or right reference position.

  FIG. 4 is an enlarged perspective view showing the detailed shape of the seat support portion 14. The sheet support portion 14 is formed by forming a rib-like convex portion having a flat sheet support surface 13 in contact with the back surface of the sheet into a rectangular frame shape. A suction recess (suction portion) 17 one step lower than the sheet support surface 13 is formed inside the sheet support portion 14. The suction recess 18 is provided with a suction hole 18 penetrating from the front surface to the rear surface. Further, in order to prevent the sheet from falling into the suction recess 17, the suction recess 17 is provided with an intermediate rib 14 r having a sheet support surface having the same height as the sheet support surface 13. It is desirable that the surface of the intermediate rib 14r is continuous with the sheet support surface 13 and extends in the sheet conveyance direction (Y direction).

  Next, the configuration of the ink receiving portion formed on the platen will be described. An ink receiving portion for receiving the ink discharged to the outside of the sheet 2 is formed around the sheet support portion 14. In order to reliably perform so-called borderless printing in which printing is performed on the entire sheet without providing a margin on the sheet periphery, it is necessary to discharge the ink to the outside of the sheet edge. Further, in the inkjet type printing apparatus, in order to stabilize the ink ejection performance of the print head 3, so-called preliminary ejection is performed in which the ink is ejected to the outside of the sheet immediately before the printing operation. The ink ejected to the outside of such a sheet is received by the ink receiving portion formed on the platen 9.

  As shown in FIGS. 3 and 4, the ink receiving portion includes a tip end ink discarding groove 31A for receiving the ink discharged to the outside from the tip 2a of the sheet, and the ink discharged to the outside from the rear end 2b of the sheet. A rear end ink discarding groove 31B is provided. The front end ink discarding groove 31A extends in the X direction so as to be adjacent to the downstream side of the sheet support portion 14, and the rear end ink discarding groove 31B is adjacent to the upstream side of the sheet support portion 14. It is elongated in the direction. Further, as the ink receiving portion, left and right end ink discarding grooves 34 for receiving the ink discharged to the outside from the left and right ends (sheet side end) of the sheet 2 in the sheet width direction are provided. The left and right end ink discarding grooves 34 extend in the Y direction, and connect the upstream ink discarding groove 31B and the downstream ink discarding groove 31A. As described above, on the surface side of the platen 9, the tip end 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 grid shape. ing.

  FIG. 5 is a longitudinal cross-sectional side view showing a part of the platen 9, and here, the ink discarding groove (first ink receiving portion) 31A for the tip of the platen 9 and the ink discarding groove (second ink) for the rear end The cross section of the receiving portion 31B is shown. The ink discarding grooves 31A and 31B are formed of a bottom 31a and a side wall 31b lower than the sheet supporting surface 13, and have a shape capable of temporarily storing the received ink.

  As described above, assuming that borderless printing is performed on the four sides of the cut sheet, the sheet support portion 14 of the platen 9 is first, the ink discarding grooves 31A and 31B for the rear end, and the ink discarding grooves for the left and right ends of the sheet. (Third ink receiver) 34, and forms an isolated form. Further, in each ink discarding groove, an ink absorber 35 is disposed so as to receive the ejected ink and hold the received ink without leaking. The material of the ink absorber 35 is preferably made of a single sponge-like sheet material such as urethane foam. By forming the ink absorber 35 of such a material having ink absorbability, it becomes possible to reliably receive the ink from the print head 3, and the received ink is permeated and held inside while being discharged. It is possible to lead to the exit.

1.2 Air Channel FIG. 6 is a longitudinal sectional side view showing an air channel from the platen 9 provided in the printing apparatus 1 to the suction fan 19, and FIG. 7 is a perspective view showing the internal structure of the platen. A duct 66 with a hollow inside is formed of a cover member 63 provided with a plurality of first openings 63 a on the upper surface and a base member 64 provided with a second opening 64 a on the lower surface directly below the platen 9. Is provided.

  The platen 9 includes an outer peripheral wall 61 surrounding the periphery at the lower side, and a dividing wall 69 dividing a space formed by the outer peripheral wall into a plurality of small spaces. The outer peripheral wall 61 and the dividing wall 69 are engaged with the upper surface of the cover member 63 so as to enclose each of the plurality of first openings 63 a formed in the cover member 63, whereby the plurality of first openings 63 a are formed. A negative pressure chamber 62 is formed.

  Each first negative pressure chamber 62 corresponds to one or two sheet support portions 14 provided in the platen 9. Here, each negative pressure chamber is arranged directly below the corresponding one or two seat supports 14 (see FIG. 7). As shown in FIG. 6, one first opening 64a is formed on the lower surface of the base member 64, and the suction port of the suction fan 19 which is a negative pressure generating means is engaged so as to enclose the first opening 64a. It is correct. As a result, one second negative pressure chamber 65 is formed inside the duct 66. The second negative pressure chamber 65 communicates with the plurality of first negative pressure chambers 62 by the plurality of first openings 63 a, and suction of the platen 9 by the first negative pressure chamber 62 and the second negative pressure chamber 65. An air flow path is formed from the hole 18 to the suction fan 19.

  Here, the engagement portion between each of the outer peripheral wall 61 of the platen 9 and the bottom side of the division wall 69 and the upper surface of the cover member 63 and the engagement portion between the second opening 64 a of the base member 64 and the suction fan 19 A seal member 68 is disposed to suppress air leakage. The sealing member 68 is preferably made of EPDM, which is soft and has a high sealing property so as not to deform the platen 9 and the cover member 63 due to its repulsive force when compressed. By interposing the seal member 68 between the respective members, transmission of vibration from the suction fan 19 to the platen 9 can be suppressed while maintaining the sealing property between the respective members.

The platen 9 is supported by a platen chassis 67 disposed on the upstream side and the downstream side, the platen chassis 67 is fixed to a main chassis (not shown) that supports the transport roller 7 and the carriage 4, and the duct is via the chassis Fixed to the main chassis.
In addition, it is preferable to use a sirocco fan or the like having a high suction efficiency as the suction fan 19 as the negative pressure generating means. The suction fan 19 can adjust the suction air volume by PWM control. By making the suction air volume variable according to the type of sheet, the state of the sheet, and the use atmosphere environment, it is possible to adjust the adsorptivity of the sheet.

  The platen 9 is manufactured as one component by resin molding. That is, the plurality of sheet support portions 14, the plurality of first negative pressure chambers 62, and the ink receiving portions (first to third ink receiving portions) are collectively formed into one resin mold component constituting the platen 9. It is done. As a result, the manufacturing of the printing apparatus is simplified, and the relative positional accuracy of the functional units can be improved.

1.3 On-off valve As shown in FIG. 7, among the plurality of first openings 63 a provided in the above-described air flow path, the first two other than the first two first openings 63 a in the sheet width direction (X direction) A first on-off valve 80 is provided in the first opening 63a.

  FIG. 8 is a perspective view showing a configuration of one on-off valve 80 provided in the first opening 63a. In FIG. 8, the on-off valve 80 includes a valve plate 81, a plate restraining spring 82 and a cam 90. The valve plate 81 includes a plate member 83, a cam follower (not shown), and a rotating shaft 84. The valve plate 81 is rotatably supported by the rotation shaft 84 so as to be able to open and close the opening 85a of the bank portion 85 of the duct provided around the first opening 63a. It is biased in the direction of closing the opening 85 a of the bank portion 85. When the cam follower abuts on the cam 90 and the valve plate 81 is separated from the bank portion 85 against the biasing force of the plate holding spring 82, the on-off valve 80 is opened as shown in FIG. 8A. . Further, when the cam follower separates from the valve plate 81 by the cam 90, the valve plate 81 is pushed down by the biasing force of the plate holding spring 82, and the on-off valve 80 is in the closed state shown in FIG.

  FIG. 9 is a view showing the arrangement of the cams 90 provided corresponding to the plurality of valve plates 81. Here, one side (left side from the position corresponding to the center of the platen 9 in the sheet width direction (X direction) And a portion of the valve plate 81. The cam 90 is a disc cam and is provided in the second negative pressure chamber 65. The plurality of cams 90 are fixed to a common shaft 96 so as to rotate coaxially. Further, the cams are provided with cam surfaces having different cam phases so as to sequentially open from the on-off valve 80 closer to the center in the sheet width direction, that is, the center of the platen 9. Although not shown in FIG. 9, the cam 90 and the valve plate 81 on the opposite side (right side) from the center in the seat width direction are similarly configured.

  FIG. 10 is a perspective view showing a drive mechanism of the cam 90. As shown in FIG. The shaft 96 penetrates the wall of the second negative pressure chamber 65 and is engaged with a cam gear 91 located outside the second negative pressure chamber 65. The rotation of the drive shaft of the cam drive motor 93 is transmitted to the cam gear 91 through the gear train 94. The cam gear 91 is provided with a flange 92 in which a notch is formed in a part in the circumferential direction, and when the photosensor 95 detects the notch of the flange 92, the cam 90 is in an initial phase. The cam drive motor 93 is provided with a rotary encoder, and the amount of rotation of the drive shaft of the cam drive motor 93 is controlled based on the rotary encoder output to rotate and stop the cam 90 so as to have a desired rotational phase.

  The supply of negative pressure to each of the plurality of negative pressure chambers is individually adjusted by the drive mechanism of the first opening 63a provided in each negative pressure chamber, the on-off valve 80, the cam 90, and the cam 90 described above. Adjustment means are configured.

1.4 Control System FIG. 11 is a block diagram showing a control system configuration of the printing apparatus. A head drive circuit 102 that controls ink ejection of the print head 3 is connected to the CPU 101. Further, a motor drive circuit 103 for controlling motors (carriage motor 104, conveyance roller motor 105, feed roller motor 106, suction fan 19, cam drive motor 93, etc.) for operating each mechanism is connected to the CPU 101. .

  The suction fan 19 is subjected to PWM control by the motor drive circuit 103, and it is possible to adjust the air flow and adjust the suction negative pressure of the sheet suction unit. Changing the air flow rate according to the type of sheet, the state of the sheet, the condition of the atmosphere environment, etc. is an effective means for adjusting the sheet transportability. Further, it is also possible to change the air volume depending on the position of the carriage 4 and the condition of the sheet conveyance position.

1.5 Print Operation Next, the print operation by the printing apparatus will be described. When the CPU 101 of the printing apparatus 1 receives a print command including sheet size information from an external host computer, the CPU 101 executes the control operation shown in the flowchart of FIG. First, the motor drive circuit 103 is controlled to drive the suction fan 19 (S101), and the cam drive motor 93 is driven to rotate the cam 90 to the initial phase (S102). At this time, all the on-off valves 80 are in the closed state, that is, the communication between the first negative pressure chamber 62 and the second negative pressure chamber 65 is blocked. Thereafter, the cam drive motor 93 is driven to rotate the cam 90 to a phase corresponding to the sheet width of the input size sheet, and the on-off valve 80 corresponding to only the sheet support surface 13 supporting the sheet 2 is opened. The state (communication state) is set (S103). However, as shown in FIG. 13, when the left end 2 c of the sheet is positioned within the sheet support surface 13, the on-off valve 80 b corresponding to the sheet support surface 13 is in the closed state. That is, control is performed such that only the on-off valve 80a corresponding to the sheet support surface 13a completely covered by the right end 2d side of the sheet is opened.

  A negative pressure is supplied by the suction fan 19 to the first negative pressure chamber 62 communicated with the second negative pressure chamber 65 by the open / close valve 80a. Thus, the air in the suction recess 17 is sucked through the suction hole 18 communicating with the first negative pressure chamber 62 to which the negative pressure is supplied, and the sheet 2 passing therethrough is sucked by the sheet support portion 14. Become. Thus, negative pressure can be separately supplied to the plurality of first negative pressure chambers 62 by opening and closing the on-off valve 80a. Further, the first negative pressure chamber 62 to which the negative pressure is to be supplied is selected according to the sheet width input in advance.

  After the above preparation operation is completed, the CPU 101 drives the feed roller motor 106 and the conveyance roller motor 105 via the motor drive circuit 103 to rotate the feed roller 6 and the conveyance roller 7. As a result, one sheet is fed from the feeding tray 5 to the conveying roller 7, and the conveying roller 7 receiving the sheet further conveys the sheet 2 to a position covering the sheet support surface 13 of the platen 9. After the leading edge 2a of the sheet 2 passes between the sheet supporting surface 13 and the print head 3 by this conveyance operation, the leading edge 2a is on the leading edge ink discarding groove 31A and further than the lowermost downstream outlet 3d of the outlet row 3b. It reaches a position that is upstream in the Y direction.

  Next, the CPU 101 drives the carriage motor 104 via the motor drive circuit 103 to start movement of the carriage 4 in the X direction, and simultaneously causes the print head 3 to eject ink via the head drive circuit 102. Thus, the printing operation on the sheet 2 is performed. When the printing operation performed at this time is so-called borderless printing in which the image is formed on the entire sheet 2 without forming a margin at the end of the sheet 2, the ink is applied to the area from the outside to the inside from the leading edge 2a Is discharged. At this time, even if ink is discharged from all the discharge ports of the discharge port array 3b, the discharge port 3d located at the most downstream position is located above the ink discarding groove 31A for the leading edge, so All the ink ejected to the above is received by the ink absorber 35. Further, since the left and right ends 2 c and 2 d of the sheet 2 are also positioned on the left and right end ink discarding grooves 34 disposed between the sheet support portions 14, all the ink discharged to the outside of the sheet 2 is ink It is received by the absorber 35. Therefore, the sheet support surface 13 of the platen 9 is not contaminated with ink.

  At this time, the air inside the suction recess 17 is being discharged by the suction fan 19 rotating by the above-mentioned preparation operation. For this reason, negative pressure is generated in the space from the suction fan 19 to the back surface of the sheet 2 by covering the suction concave portion 17 with the sheet. The sheet 2 is attracted to the sheet support surface 13 by this negative pressure, and floating and deflection from the sheet support surface 13 are suppressed. Therefore, the distance between the discharge port forming surface 3 a of the print head 3 and the sheet 2 is kept constant. In this state, printing on the sheet 2 proceeds by repeating the discharge of the ink by the print head 3 and the intermittent conveyance operation of the sheet 2 (S105).

  Thereafter, the rear end 2b of the sheet 2 passes through the first conveyance roller pair, and as shown in FIG. 14B, the rear end 2b of the sheet 2 is on the rear end side ink discarding groove 31B and is most upstream The final printing operation is performed in a state in which the position downstream of the discharge port 3c in the Y direction is reached. At this time, even if all the discharge ports of the discharge port array 3 b are used, all the ink discharged to the outside (upstream side) of the sheet 2 is received by the ink absorber 35, and the rear end side of the sheet 2 Borderless printing to is properly completed. Thereafter, the sheet 2 is discharged onto the discharge tray 12 by the rotation of the discharge roller 10 (S106). When the discharge of the sheet 2 is completed, the CPU 101 stops the drive of the suction fan 19 via the motor drive circuit 103.

  Here, when the printing operation of the sheet of the same size is subsequently performed, the rotation operation (S102) to the initial phase of the cam 90 and the stop of the suction fan 19 may be omitted. Further, in the printing operation process, it is also possible to change the suction intensity of the suction fan 19 or switch the drive / stop, and by changing the drive timing and the number of rotations of the suction fan 19 as necessary. The sheet 2 can be adsorbed with an optimum adsorption power.

  On the other hand, even in so-called bordered printing in which a margin is formed along the edge of the sheet 2, the sheet 2 always covers the sheet supporting surface 13 during the printing operation. For this reason, the sheet 2 is adsorbed to the sheet support surface 13 by the negative pressure generated in the adsorption concave portion 17 formed inside the sheet support portion 14, and the floating and bending of the sheet 2 from the sheet support surface 13 are suppressed. Therefore, even in the bordered printing, the distance between the discharge port forming surface 3 a of the print head 3 and the sheet 2 can be properly maintained.

  As described above, since the sheet 2 is always on the sheet support surface 13 of the sheet support portion 14 from the start of the printing operation to the end of the printing operation, if an appropriate negative pressure is introduced into the suction recess 17, the sheet 2 can be The printing operation can be performed in a state of being attracted to the 13. Therefore, the distance between the print head 3 and the sheet 2 can be properly maintained, and ink droplets of an optimal shape can be made to land on the sheet surface at the optimal position, and a high quality image can be formed. it can. Further, since the on-off valve 80 corresponding to the sheet support portion 14 outside the end of the sheet 2 is closed, the generation of air flow flowing from the end of the sheet 2 to the outside is reduced, and the end of the ink droplet due to the air flow It is possible to reduce the sideward whirl. Therefore, borderless printing can be performed properly and reliably on sheets of various sizes.

  Next, a second embodiment of the present invention will be described. In the first embodiment, when the printing operation is started, the on-off valve is opened or closed in accordance with the sheet size (sheet width) input from the host computer. However, since a sheet different from the input sheet may be fed, in the present embodiment, the sheet width of the sheet actually fed is automatically detected, and the sheet is opened or closed based on the detection result. The opening and closing of the valve 80 is controlled.

  Here, first, the sheet width detection operation performed in the present embodiment will be described. The carriage 4 in the present embodiment is provided with an optical sensor at a position facing the platen 9. This optical sensor is composed of an LED as a light emitting unit and a light receiving element as a light receiving unit. The LED emits light toward the platen 9, the light receiving unit receives the reflected light of the light emitted by the LED, and sends a detection signal corresponding to the amount of light received to the CPU 101. When a sheet is present immediately below the light emitting unit, most of the light emitted from the light emitting unit is reflected by the sheet, and a lot of light is incident on the light receiving unit, and a high level signal is received from the light receiving unit. It is output. In addition, when no sheet is present immediately below the light emitting unit, the amount of light received by the light receiving unit is significantly reduced, and a low level signal is output from the light receiving unit. Then, based on the output signal from the light receiving unit, the CPU 101 determines the presence or absence of the sheet immediately below the optical sensor. The sheet width can be detected by moving the carriage 4 in the X direction to determine the presence or absence of the sheet. That is, while the carriage 4 is moved, the presence or absence of the sheet is determined based on the detection result of the optical sensor. Then, the determination result stores the position A of the carriage 4 when the sheet is switched to the absence of a sheet, and the position B of the carriage 4 when the sheet is switched from the absence of the sheet to the presence of the sheet. The sheet width is determined from the difference between the stored carriage positions A and B.

  FIG. 15 is a flowchart showing a series of printing operations of the present embodiment including the automatic detection of the sheet width as described above. The operations in S101 to S104, S105, and S106 in FIG. 15 are the same as in the first embodiment, and thus the description thereof is omitted.

  When the leading end 2 a of the fed sheet 2 reaches a predetermined position on the platen 9, the conveyance of the sheet 2 is stopped. Here, the sheet width detection described above is performed (S110). If the difference between the detected sheet width and the input sheet width is equal to or less than a predetermined value, it is determined that a sheet of a predetermined size is being fed, and opening and closing of the position corresponding to the sheet width input in advance Open the valve (S112) and print. On the other hand, when the difference between the detected sheet width and the sheet width input in advance exceeds a certain value, it is determined that a sheet having a sheet width different from the sheet width input in advance is fed. Then, the on-off valve 80 at a position corresponding to the sheet width detected by the detection operation is opened (S112), and printing is performed.

  In the second embodiment, even when the previously input sheet and the sheet actually conveyed have different sheet widths, the on-off valve corresponding to the sheet width is opened to print on the sheet in an appropriate suction state. It can be performed.

  Note that the printing operation may be performed based on only the result of automatically detecting the sheet width without inputting the sheet width at all. Furthermore, when it is determined that the input sheet width and the sheet width actually fed are different, the printing operation is stopped to notify the user that an unscheduled sheet is being fed. It is also possible.

  According to the embodiment described above, four-edge printing can be performed on a cut sheet. Then, borderless printing can be reliably performed on sheets of various sizes.

1 printing apparatus 3 print head 7 conveying roller (conveying means)
9 platen 13 sheet support surface (support surface)
14 Seat Support (Support)
17 Recesses (Suction Recess)
18 suction hole 19 suction fan (suction means)
80 on-off valve 101 CPU (control means)

The present invention relates to an inkjet printing apparatus and a control method thereof .

According to an embodiment of the present invention for solving the above-mentioned problems, there is provided a print head for discharging ink, a conveying means for conveying a sheet in a first direction, and a movement in a second direction which carries the print head and intersects the first direction. a carriage for said platen for supporting a sheet to be conveyed by the print head facing the disposed position said transport means comprises a suction means, and said platen, a sheet provided along the front Stories second direction A plurality of support portions provided with a support surface in contact with the support surface, a recess surrounded by the support surface and not in contact with the sheet, and a suction hole provided in the recess and connected to the suction unit; a printing apparatus having an opening and closing valve for opening and closing the communication between the hole and the suction means, a detectable detection means end of the sheet in the second direction is mounted on the carriage , And further comprising a control means for controlling the detection result closing of the on-off valve on the basis of said detection means.

Claims (1)

The printing apparatus includes: a print head that discharges ink; a transport unit that transports a sheet in a first direction; a platen that is disposed at a position facing the print head and supports the sheet transported by the transport unit; ,
The platen is provided along a second direction intersecting the first direction, and is provided with a support surface that contacts the sheet, a recess that is surrounded by the support surface and does not contact the sheet, and the suction unit that is provided in the recess. A printing apparatus, comprising: a plurality of support portions provided with suction holes connected thereto; and an on-off valve for opening and closing communication between the suction holes and the suction means.
A printing apparatus comprising: detection means capable of detecting an end of a sheet; and control means for controlling the opening and closing of the on-off valve based on the detection result of the detection means.