JP6523189B2 - Image forming device - Google Patents

Description

  The present invention relates to an image forming apparatus for forming an image on a recording medium such as paper.

  Immediately below the image forming means of the image forming apparatus, it is necessary to maintain the flatness of the recording medium and transport it in order to prevent the disturbance of the formed image. For this purpose, a so-called air suction type transport mechanism is widely used. A registration roller is installed on the upstream side of the air suction type conveyance mechanism, and the recording medium whose skew has been corrected is conveyed at a predetermined timing (for example, see Patent Document 1).

  In the air suction type conveyance mechanism, the suction fan sucks air from above the conveyance belt through many belt holes provided in the conveyance belt by the suction fan, and the negative pressure generated in the belt holes exerts an adsorption force. By suction on the conveyor belt. The conveyance belt conveys the sheet by moving while suctioning and holding the sheet in this manner.

JP 2007-76175 A

  In the image forming apparatus, when a sheet jam occurs, the conveyance is stopped. As a result, the sheet in the process of being conveyed remains in the apparatus. The paper remaining in the device must be removed by the user.

  Here, in the image forming apparatus having the air suction type conveyance mechanism, the suction force is applied during the normal conveyance to adsorb the sheet on the conveyance belt, so the sheet is conveyed when the conveyance is stopped when the jam occurs. It remains in close contact with the belt. Since the residual negative pressure and the like by the suction fan act on the residual sheet, the sheet is in close contact with the conveying belt without a gap, and it is not easy for the user to remove the residual sheet.

  The present invention has been made in view of the above, and provides an image forming apparatus capable of efficiently performing a work when a user removes a recording medium such as a sheet which will remain in the apparatus as a jam. The purpose is

  In order to achieve the above object, a first feature of an image forming apparatus according to the present invention is an image forming unit for forming an image on a recording medium, and a unit disposed immediately under the image forming unit for conveying the paper recording medium A jam is generated from a conveyance unit that conveys downstream on a belt in close contact with one or more detection units that detect the position of the recording medium, and information from the detection unit and the conveyance amount by the conveyance unit. A control unit that determines occurrence and specifies the position of the recording medium on the conveyance belt at the time of jam occurrence, and the control unit is configured to position the leading end and the rear end of the recording medium on the conveyance belt when the jam occurs First conveyance processing for causing the recording medium to convey the recording medium to a position where a part of the front end side of the recording medium in the conveyance direction jumps out from the end of the conveyance belt. To do A.

  A second feature of the image forming apparatus according to the present invention is, in the image forming apparatus having the first feature, further provided with an adjusting unit for adjusting the distance between the image forming unit and the conveyance unit, the control unit When the jamming is detected, the adjusting unit starts the separation process of separating the distance, and the first post-jamming conveyance process is performed while the separation process is performed.

According to a third aspect of the image forming apparatus of the present invention, in the image forming apparatus having the first or second aspect, a resist roller for supplying the recording medium to the transport unit, and an upstream end of the transport belt The recording medium may further include a pressing roller for pressing the recording medium onto the conveyance belt, and when the control unit detects the jam, the recording medium straddles the registration roller and the conveyance belt. Control the drive of the transport belt and the registration roller when it is specified that the rear end of the recording medium is present at a position of a predetermined length or more upstream of the position of the registration roller. Forming a slack in the recording medium, and controlling the conveyance of the recording medium so that the slack is crushed when the rear end of the recording medium passes the pressing roller. It is to perform the beam after conveyance process.

  According to a first feature of the image forming apparatus according to the present invention, when the control unit determines that the positions of the leading end and the rear end of the recording medium are present on the transport belt unit when a jam occurs, that is, directly under the image forming unit. When it is determined that the entire recording medium present in the recording medium is adsorbed by the conveyance belt, the conveyance unit is controlled to perform the first post-jamming conveyance processing, and a part of the leading end side of the recording medium is conveyed Since the conveyance processing of the recording medium is performed so as to be in a state of being ejected from the belt end, it is possible to intentionally form a portion on the leading end side of the recording medium from which the adsorption by the residual negative pressure is released. The user can easily remove the recording medium remaining in the apparatus by utilizing this protruding part.

  According to the second aspect of the conveyance device of the present invention, when the control unit detects a jam, the adjustment unit starts the separation process and causes the first post-jamming conveyance process to be performed during the execution of the separation process. Execute the first post-jump conveyance process without waiting for the end of the separation process, that is, execute the separation process and the first post-jump conveyance process in parallel, thereby reducing the time required to remove the remaining recording medium. Can lead to reduced equipment downtime.

  According to a third aspect of the image forming apparatus of the present invention, when the control unit detects a jam, the control unit determines that the recording medium is present at a position straddling the registration roller and the conveyance belt. Execute post-jam conveyance processing. For example, the conveyance belt is driven at a lower speed than the registration rollers, and the conveyance amount of the registration rollers is set smaller than the conveyance amount of the conveyance belt to form a slack in the recording medium. Then, the slack formed by continuing the conveyance is crushed by the pressure roller and the conveyance belt, whereby a fold can be intentionally created on the recording medium in the direction orthogonal to the conveyance direction. Therefore, the user can easily remove the recording medium remaining in the apparatus by picking up and utilizing the broken part.

FIG. 1 is a schematic configuration view of an image forming apparatus according to a first embodiment. FIG. 2 is a control block diagram of the image forming apparatus shown in FIG. FIG. 2 is a schematic configuration view of a belt platen unit of the image forming apparatus shown in FIG. FIG. 4 is a partial enlarged plan view of a conveyor belt and a plastic template of the belt platen unit shown in FIG. 7 is a flowchart illustrating print processing including a post-jam conveyance operation. FIG. 8 is an explanatory view for explaining a post-jamming conveyance operation when the entire recording medium is positioned on the belt platen when a jam occurs. FIG. 7 is an explanatory view for explaining a post-jamming conveyance operation when the recording medium is positioned by the belt platen and the registration roller pair when a jam occurs.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or equivalent parts or components are denoted by the same or equivalent reference numerals throughout the drawings.

  The embodiment shown below exemplifies an apparatus etc. for embodying the technical idea of this invention, and the technical idea of this invention is the material, shape, structure, arrangement etc. of each component. Does not specify the following. Various changes can be added to the technical idea of the present invention within the scope of the claims.

First Embodiment
FIG. 1 is a schematic configuration diagram of an image forming apparatus provided with a conveyance device according to a first embodiment of the present invention. FIG. 2 is a control block diagram of the image forming apparatus shown in FIG. FIG. 3 is a schematic configuration view of a belt platen unit of the image forming apparatus shown in FIG. FIG. 4 is a partial enlarged plan view of a conveyor belt and a plastic template of the belt platen unit shown in FIG. In the following description, the direction orthogonal to the paper surface of FIG. 1 is referred to as the front-rear direction, and the front direction of the paper surface is referred to as the front. Further, the top, bottom, left, and right of the sheet of FIG. 1 are referred to as the top, bottom, left, and right directions.

A path indicated by a thick line in FIG. 1 is a transport path through which the sheet P, which is a print medium, is transported. Of the transport routes, the route indicated by the solid line is the normal route RC, the route indicated by the alternate long and short dash line is the reverse route RR,
A path indicated by a broken line is a sheet discharge path RD, and a path indicated by a two-dot chain line is a sheet feed path RS. In the following description, upstream and downstream mean upstream and downstream in the transport path.

  As shown in FIGS. 1 and 2, the image forming apparatus 100 according to the first embodiment includes a sheet feeding unit 1, a conveyance unit 2, an upper surface conveyance unit 4, a sheet discharge unit 5, and a reversing unit 6. An operation panel 7, a control unit 8, and a housing 9 for storing or holding each part are provided.

  The sheet feeding unit 1 feeds a sheet P, which is a print medium, to the conveyance unit 2. The sheet feeding unit 1 is disposed on the most upstream side of the conveyance path. The paper feeding unit 1 includes an external paper feeding unit 11, an internal paper feeding unit 12, and a vertical conveyance unit 13.

  The external sheet feeding unit 11 is disposed in a state where a part thereof is exposed to the outside of the housing 9, and feeds the stacked sheets P. The external sheet feeding unit 11 includes an external sheet feeding table 21, an external sheet feeding roller 22, and an external sheet feeding motor 23.

  The external sheet feeding table 21 is a stack of sheets P used for printing. A part of the external sheet feeding table 21 is exposed to the outside of the housing 9 and installed. Further, the external sheet feeding roller 22 picks up the sheets P stacked on the external sheet feeding tray 21 one by one, and conveys the sheet P toward the conveyance unit 2 along the sheet feeding path RS. The external sheet feeding roller 22 is disposed above the right end of the external sheet feeding table 21. The external sheet feeding roller 22 is rotationally driven by the external sheet feeding motor 23.

  The internal sheet feeding unit 12 conveys the sheet P to be fed within the housing 9 to the vertical conveyance roller 31. The internal sheet feeding unit 12 includes three internal sheet feeding bases 26, three internal sheet feeding rollers 27, four pairs of internal sheet feeding and conveying rollers 28, an internal sheet feeding motor 29, and sheet sensors 30a to 30d. Prepare.

  The internal sheet feeding table 26 is a stack of sheets P used for printing. The internal paper feed tray 26 is disposed inside the housing 9.

  The internal sheet feeding roller 27 takes out the sheets P one by one from the internal sheet feeding table 26 and feeds the sheet P to the sheet feeding path RS. The internal sheet feeding roller 27 is disposed above the left end of the internal sheet feeding table 26.

  The internal sheet feeding and conveying roller 28 conveys the sheet P taken out of the internal sheet feeding table 26 toward the vertical conveying roller 31. The internal sheet feeding conveyance roller 28 is disposed along the sheet feeding path RS.

  The internal sheet feeding motor 29 rotationally drives the internal sheet feeding roller 27 and the internal sheet feeding conveyance roller 28. The internal sheet feeding motor 29 can be connected / released to the respective internal sheet feeding rollers 27 and the respective internal sheet feeding / conveying rollers 28 via a clutch (not shown). The internal sheet feeding roller 27 and the internal sheet feeding conveyance roller 28 which are rotationally driven are switched by the clutch.

  The sheet sensors 30 a to 30 d detect the sheet P taken out from the internal sheet feeding table 26 and conveyed along the sheet feeding path RS. The sheet sensors 30 a to 30 d are disposed in the vicinity of the downstream side of the respective internal sheet feeding and conveying rollers 28.

  The vertical conveyance unit 13 includes a vertical conveyance roller 31 and a sheet sensor 34. The vertical conveyance roller 31 conveys the sheet P from the internal sheet feeding unit 12 to the conveyance unit 2. The external sheet feeding roller 22 is rotationally driven by the external sheet feeding motor 23.

  The vertical conveyance roller 31 conveys the sheet P conveyed by the internal sheet feeding conveyance roller 28 to the registration roller 41 described later. The vertical conveyance roller 31 is disposed along a vertical portion in the lower area of the paper feed path RS along which the paper P from the internal paper feed table 26 is conveyed. Further, the sheet sensor 34 is disposed near the downstream side of the vertical conveyance roller 31. The sheet sensor 34 detects the sheet P conveyed from the vertical conveyance roller 31 to the registration roller 41.

  The conveyance unit 2 forms (prints) an image on the sheet P while conveying the sheet P. The transport unit 2 is disposed downstream of the sheet feeding unit 1. The transport unit 2 includes a registration roller 41, a registration motor 42, a belt platen unit 43, and sheet sensors 46a and 46b. Further, the image forming unit 3 includes a head unit 44 and an elevation driving unit 45.

  The registration roller 41 is a roller pair that temporarily stops the sheet P conveyed by the sheet feeding unit 1 or the reversing unit 6 and corrects the skew, and then conveys the sheet P to the belt platen unit 43 at a predetermined timing. The registration roller 41 is disposed on the normal path RC on the upstream side of the conveyance unit 2.

  The resist motor 42 rotationally drives the resist roller 41. The resist motor 42 is a motor that can rotate in both forward and reverse directions.

  The belt platen unit 43 corresponds to the conveyance unit described in the claims. The belt platen unit 43 is disposed immediately below the head unit 44 that is an image forming unit. The belt platen unit 43 transports the sheet P transported by the registration roller 41 while keeping the sheet P in close contact with the belt by, for example, air suction. The belt platen unit 43 is vertically movable between the printing position and the retracted position by the elevation driving unit 45. The printing position is the position of the belt platen unit 43 when printing is performed. The printing position is the position of the belt platen unit 43 indicated by a solid line in FIG. The retracted position is the position of the belt platen unit 43 at the time of the jam release operation. The retracted position is the position of the belt platen unit 43 indicated by a two-dot chain line in FIG. 1 and is below the printing position.

  As shown in FIG. 3, the belt platen unit 43 includes the conveyance belt 51, the drive roller 52, the driven rollers 53 to 55, the belt platen motor 56, the encoder 57, the plague template 58, the chamber 59, and the fan. 60 and a pressure roller 64.

  The conveyance belt 51 is an annular belt which is wound around the driving roller 52 and the driven rollers 53 to 55. The conveyance belt 51 is made of a material that generates an appropriate frictional force with the sheet P. The conveyance belt 51 receives the sheet P from the registration roller 41 and conveys the sheet P to the downstream side. That is, the conveyance belt 51 conveys the sheet P in conjunction with the registration roller 41.

  As shown in FIG. 4, the transport belt 51 is formed with a plurality of belt holes 61 which are suction holes for air suction. The belt holes 61 are arranged at a predetermined pitch along the transport direction (left-right direction). Further, the belt holes 61 in the next step adjacent in the direction (front-rear direction) orthogonal to the transport direction are arranged to be offset by a half pitch in the transport direction with respect to the belt holes 61 in the front stage. That is, the belt holes 61 are arranged in a staggered manner.

  The conveyance belt 51 brings the sheet P into close contact with the conveyance surface 51 a by the suction action generated in the belt hole 61 by the drive of the fan 60. The conveyance surface 51 a is an upper surface of the conveyance belt 51 facing the head unit 44. At the time of printing, the conveyance belt 51 rotates in the forward rotation direction (clockwise direction in FIG. 3) to convey the sheet P, in which the close contact state is maintained, in the right direction.

  The driving roller 52 rotates the conveyance belt 51. The driving roller 52 can be rotated by the belt platen motor 56 in the forward rotation direction (clockwise direction in FIG. 3) and the reverse rotation direction (counterclockwise direction in FIG. 3). The rotation of the drive roller 52 causes the conveyance belt 51 to rotate in the same direction.

  The driven rollers 53 to 55 support the conveyance belt 51 together with the drive roller 52. The driven rollers 53 to 55 are driven by the drive roller 52 via the conveyance belt 51. The driven roller 53 is disposed to the left of the drive roller 52 at the same height as the drive roller 52. The driven rollers 54 and 55 are disposed at the same height below the driving roller 52 and the driven roller 53 so as to be separated from each other in the left-right direction.

  The belt platen motor 56 rotationally drives the drive roller 52 in the normal direction and the reverse direction.

  The encoder 57 outputs a pulse signal at each predetermined rotation angle of the driven roller 53.

  The plastic template 58 is disposed below the transport belt 51 between the drive roller 52 and the driven roller 53, and slidably supports the lower surface of the transport belt 51. The plastic template 58 is made of metal, resin or the like. The plastic template 58 has a plurality of recesses 62 dug down from the upper surface to the lower surface where the belt holes 61 pass, and a plurality of through holes 63 penetrating the lower surface of the plastic template 58 from part of the bottom surface of the recesses 62. Have. The recesses 62 and the through holes 63 are arranged in a staggered manner, similarly to the belt holes 61.

  The chamber 59 forms a negative pressure chamber for generating a suction action in the belt hole 61 of the transport belt 51 via the through hole 63 and the recess 62 of the plam template 58. The chamber 59 is provided on the lower surface side of the plastic template 58.

  The fan 60 exhausts the chamber 59. Thereby, the fan 60 generates a negative pressure in the chamber 59 and sucks air through the through hole 63, the recess 62, and the belt hole 61. As a result, the fan 60 generates a negative pressure in the belt hole 61 and causes the sheet P to be adsorbed onto the conveyance surface 51 a of the conveyance belt 51.

The pressure roller 64 is disposed on the conveyance belt 51, and is driven to rotate by the conveyance belt 51 being driven. The pressure roller 64 guides the sheet onto the conveyance belt 51 and assists the start of the adsorption onto the conveyance belt 51 by the fan 60 so that the conveyed sheet is surely adsorbed onto the conveyance belt 51. .

  The head unit 44 discharges ink on the sheet P conveyed by the belt platen unit 43 to print an image. The head unit 44 includes a plurality of inkjet heads 66 and a head holder 67.

  The ink jet head 66 has a plurality of nozzles arranged along the front-rear direction (main scanning direction), and ejects ink from the nozzles. The plurality of inkjet heads 66 are arranged in parallel along the conveyance direction (left and right direction) of the sheet P.

  The head holder 67 holds the ink jet head 66. The head holder 67 is formed in a hollow rectangular parallelepiped shape. The head holder 67 is fixed at a predetermined position in the housing 9.

  The elevation driving unit 45 raises and lowers the belt platen unit 43 between the printing position and the retracted position. The elevation drive unit 45 is disposed in the head holder 67. The elevation driving unit 45 includes a wire, a pulley, a motor, and the like, and suspends and supports the belt platen unit 43 by the wire. The elevation drive unit 45 raises and lowers the belt platen unit 43 by rotating the pulley with a motor to wind and draw the wire. The elevation drive unit 45 corresponds to the adjustment unit in the claims.

  The sheet sensor 46 a detects the sheet P conveyed from the sheet feeding unit 1 or the reversing unit 6 to the registration roller 41. The sheet sensor 46 a is disposed near the upstream side of the registration roller 41.

  The sheet sensor 46 b detects the sheet P conveyed from the registration roller 41 to the belt platen unit 43. The sheet sensor 46 b is disposed between the registration roller 41 and the belt platen unit 43.

  The upper surface conveyance unit 4 conveys the sheet P conveyed by the belt platen unit 43 to the paper discharge unit 5 or the reversing unit 6. The upper surface conveyance unit 4 includes two pairs of upward conveyance rollers 71, an upward conveyance motor 72, four pairs of horizontal conveyance rollers 73, a horizontal conveyance motor 74, and sheet sensors 75a to 75c.

The rising conveyance roller 71 is disposed along the rising portion of the middle area of the normal route RC. The rising conveyance roller 71 is a roller pair which conveys the sheet P conveyed by the conveyance belt 51 of the belt platen unit 43 to the upper horizontal conveyance roller 73. That is, the rising conveyance roller 71 conveys the sheet P to the downstream side in conjunction with the conveyance belt 51.

  The lift conveyance motor 72 rotationally drives the two pairs of lift conveyance rollers 71. The lift conveyance motor 72 is a motor that can rotate in either the normal direction or the reverse direction.

  The horizontal conveyance roller 73 conveys the sheet P conveyed by the upward conveyance roller 71 to the sheet discharge unit 5 or the reversing unit 6. The most downstream horizontal conveyance roller 73 is disposed along the upstream portion of the reverse path RR. The other three pairs of horizontal conveyance rollers 73 are disposed along the horizontal portion of the downstream area of the normal route RC.

  The horizontal conveyance motor 74 rotationally drives four pairs of horizontal conveyance rollers 73.

  The sheet sensors 75 a to 75 c detect the sheet P conveyed by the upper surface conveyance unit 4. The sheet sensor 75 a is disposed in the vicinity of the upstream side of the upstream conveyance roller 71. The sheet sensor 75 b is disposed in the vicinity of the downstream side of the most upstream horizontal conveyance roller 73. The sheet sensor 75 c is disposed in the vicinity of the upstream side of the most downstream horizontal conveyance roller 73.

  The discharge unit 5 discharges the printed sheet P. The discharge unit 5 includes a switching unit 76, a solenoid 77, a discharge roller 78, a discharge motor 79, a discharge table 80, and a sheet sensor 81.

  The switching unit 76 switches the transport path of the sheet P between the sheet discharge path RD and the reverse path RR. The switching unit 76 is disposed at a branch point between the sheet discharge path RD and the reverse path RR.

  The solenoid 77 drives the switching unit 76.

  The sheet discharge roller 78 conveys the sheet P guided to the sheet discharge path RD by the switching unit 76 and discharges the sheet P to the sheet discharge table 80. The sheet discharge roller 78 is disposed between the switching unit 76 and the sheet discharge table 80 along the sheet discharge path RD.

  The paper discharge motor 79 rotationally drives the paper discharge roller 78.

  The paper discharge tray 80 is used to load the printed paper P discharged by the paper discharge roller 78. The sheet delivery table 80 has a tray shape protruding from the housing 9 and is installed at an incline.

  The sheet sensor 81 detects the sheet P to be discharged. The sheet sensor 81 is disposed near the downstream side of the sheet discharge roller 78.

  The reversing unit 6 reverses the single-sided printed sheet P and feeds the sheet P to the transport unit 2 again during double-sided printing. The reversing unit 6 includes a reversing roller 86, a reversing motor 87, a switchback unit 88, a sheet refeeding roller 89, a sheet refeeding motor 90, a switching gate 91, and sheet sensors 92a and 92b.

  The reversing roller 86 temporarily carries the sheet P conveyed by the horizontal conveyance roller 73 into the switchback portion 88 and then conveys the sheet P to the refeed roller 89. The reversing roller 86 is disposed on the reversing path RR between the most downstream horizontal conveyance roller 73 and the loading port of the switchback portion 88. The reversing roller 86 is rotationally driven by a reversing motor 87.

  The switchback portion 88 is a space for the reverse roller 86 to temporarily carry in the sheet P. The switchback portion 88 is formed at the lower portion of the sheet discharge tray 80. The switchback portion 88 is open in the vicinity of the reversing roller 86 in order to load the sheet P.

  The sheet re-feed roller 89 conveys the sheet P conveyed by the reverse roller 86 to the registration roller 41. The sheet re-feed roller 89 is disposed on a reverse path RR between the reverse roller 86 and the registration roller 41.

  The sheet refeed motor 90 rotationally drives the sheet refeed roller 89.

  The switching gate 91 guides the sheet P conveyed by the horizontal conveyance roller 73 to the reversing roller 86. Further, the switching gate 91 guides the sheet P discharged from the switchback portion 88 by the reversing roller 86 to the sheet re-feed roller 89. The switching gate 91 is disposed in the vicinity of the center of gravity at three positions of the horizontal conveyance roller 73, the reversing roller 86, and the refeed roller 89 at the most downstream.

  The sheet sensor 92 a detects the sheet P which is transported to the switchback unit 88 by the reversing roller 86 and then unloaded. The sheet sensor 92 a is disposed in the vicinity of the loading port of the switchback unit 88.

The sheet sensor 92 b is configured to convey the sheet P conveyed from the sheet re-feed roller 89 to the registration roller 41.
To detect. The sheet sensor 92 b is disposed in the vicinity of the downstream side of the sheet re-feed roller 89.

  The operation panel 7 displays various input screens and the like, and accepts an input operation by the user. The operation panel 7 includes a display unit (not shown) having a liquid crystal display panel and the like, and an input unit (not shown) having various operation keys, a touch panel and the like.

  The control unit 8 controls the operation of each unit of the image forming apparatus 100 in the image forming process. The control unit 8 includes a CPU, a RAM, a ROM, a hard disk and the like. In particular, in the present invention, the control unit 8 controls the conveyance of the sheet P so that the user can easily remove the sheet remaining in the image forming apparatus 100 by causing each unit to execute a predetermined operation after the jam detection. It is Further, the control unit 8 is provided with sheet detection timings in the sheet sensors 30a to 30d, 34, 46a, 46b, 75a to 75c, 81, 92a, 92b, and encoders installed in motors of respective portions such as the lift conveyance motor 72 Based on the number of output pulses of the encoder 57 of the belt platen unit 43 and the number of output pulses of the belt platen unit 43, a conveyance jam in the conveyance path is detected, and the position of the sheet P on the conveyance path when the jam is detected is specified. After the jam detection, the control unit 8 stops the ink discharge by the ink jet head 66, and the sheet feeding unit 2, the belt platen unit 43 (conveying belt 51), the upper surface conveying unit 4, the sheet discharging unit 5, and the reversing unit By controlling the respective sections 6 and carrying the sheet P, the sheet P is stopped at an appropriate position.

  The operation of the image forming apparatus 100 according to the present invention will be described.

  When a print job is input, the control unit 8 executes a printing operation. Here, the control unit 8 acquires the print setting information included in the print job, and executes single-sided printing or double-sided printing according to the content.

  In the case of single-sided printing, the control unit 8 controls the sheet feeding unit 1 to sequentially take out unprinted sheets P from any of the external sheet feeding tray 21 and the three internal sheet feeding trays 26 and feed the sheet P to the conveying portion 2 Do. Here, the control unit 8 sequentially feeds the sheets P at a timing according to the drive timing of the registration roller 41 that feeds each sheet P so that each sheet P is transported between the predetermined sheets in the belt platen unit 43. Control unit 1; Thereby, a plurality of sheets of paper P are simultaneously transported on the transport path.

  The fed sheet P is sent to the belt platen unit 43 by the registration roller 41. The sheet P that has reached the conveyance surface 51 a of the conveyance belt 51 of the belt platen unit 43 is conveyed while being adsorbed onto the conveyance surface 51 a by the adsorption force of the belt hole 61. At this time, the sheet P is printed by the ink discharged from the ink jet head 66. Here, the belt platen unit 43 is disposed at the printing position. Further, in the belt platen unit 43, the transport belt 51 is rotationally driven in the normal direction.

  The printed sheet P is conveyed from the belt platen unit 43 to the upper surface conveyance unit 4, and is conveyed by the upward conveyance roller 71 and the horizontal conveyance roller 73 in the upper surface conveyance unit 4. Then, the sheet P is guided to the sheet discharge path RD by the switching unit 76, and is discharged to the sheet discharge stand 80 by the sheet discharge roller 78.

  In the case of double-sided printing, the control unit 8 sequentially feeds unprinted sheets P at timing when the time between sheet feeding timings of the respective sheets P is doubled with respect to the sheet feeding timing in single-sided printing. Control the paper unit 1.

The fed sheet P is printed by the ink ejected from the ink jet head 66 while being conveyed by the belt platen unit 43 as in the single-sided printing. The sheet P after single-sided printing is conveyed from the belt platen unit 43 to the upper surface conveyance unit 4, and conveyed by the upward conveyance roller 71 and the horizontal conveyance roller 73 in the upper surface conveyance unit 4. Then, the sheet P is switched to the switching unit 7
6 leads to the reverse path RR.

  The sheet P guided to the reversing path RR is guided by the switching gate 91 to the reversing roller 86 in the reversing unit 6, and carried into the switchback unit 88 by the reversing roller 86. Thereafter, the sheet P is conveyed out of the switchback section 88 by the reversing roller 86 and is guided to the sheet re-feed roller 89 by the switching gate 91. Then, the sheet P is re-fed to the conveyance unit 2 by the re-feed roller 89, and is sent to the belt platen unit 43 by the registration roller 41 in the conveyance unit 2.

  Here, the sheets P after single-sided printing are re-fed at such timing that they are alternately fed to the belt platen unit 43 with the unprinted sheets P sequentially fed. As described above, in the double-sided printing, the time between the sheet feeding timings of the respective sheets P is twice that of the sheet feeding timing in the single-sided printing. For this reason, it is possible to insert the sheet P after single-sided printing between unprinted sheets P and to re-feed the sheet P after single-sided printing alternately with the feeding of the unprinted sheet P. .

  Since the sheet P after single-sided printing is reversed by the reversing unit 6, the sheet P is sent to the belt platen unit 43 with the unprinted side facing upward. Then, while the sheet P is conveyed by the belt platen unit 43, the unprinted surface is printed by the ink discharged from the ink jet head 66. The double-sided printed sheet P is conveyed to the sheet discharge unit 5 by the upper surface conveyance unit 4, and is discharged to the sheet discharge stand 80 by the sheet discharge unit 5.

As described above, in the double-sided printing, refeeding of the sheet P after single-sided printing is performed alternately with the feeding of the unprinted sheet P, one of the unprinted sheets P on the belt platen unit 43. Printing on one side of the paper and printing on the unprinted side of the paper P after single-sided printing are alternately performed. In this way, double-sided printing is performed with the same productivity per one side as single-sided printing.
(Post-jam transport control)

  The processing of the image forming apparatus after the start of single-sided printing or double-sided printing as described above will be described below with reference to the flowchart of FIG.

When the print job is received, the control unit 8 executes the printing process, and at the same time, determines the occurrence of the conveyance jam of the sheet P (steps S1 and S3). Specifically, it is determined whether or not a jam has occurred between two sensors or one in at least one of the sheet sensors 30a to 30d, 34, 46a, 46b, 75a to 75c, 81, 92a, 92b. It is determined whether an error between the detection timing of the leading end or the rear end of the sheet P in the sensor and its theoretical value is equal to or greater than a threshold, and the control unit 8 generates a jam when it is determined that the error is equal to or greater than the threshold I will judge.

If the control unit 8 determines that a jam has not occurred (step S3: No), the control unit 8 proceeds to step S23 and continues the printing process thereafter.

On the other hand, when determining that a jam has occurred (step S3: Yes), the control unit 8 specifies the position of the sheet at the time of jam detection in step S5. Here, the control unit 8 particularly specifies the position of the belt platen unit 43 in the sheet conveyance direction.

Specifically, the control unit 8 specifies the position of the sheet P based on the number of pulses output by the encoder 57 from the timing when the sheet sensor 46a or 46b detects the passage of the sheet end.

Then, whether or not the sheet P is partially present on the belt platen 43 (on the conveyance belt 51) at the time of jam detection based on the positional information of the specified sheet P (when the conveyance is stopped at this time) It is determined whether or not a part of the sheet P remains on the transport belt 51 (step S5).

If the controller 8 determines in step S5 that the sheet P does not remain on the transport belt 51, the sheet P remaining in the image forming apparatus 100 is removed without lowering the belt platen unit 43. Since it is within the possible range, the control unit 8 causes the operation panel 7 to display the presence position of the remaining sheet and the fact that the remaining sheet should be removed after stopping the conveyance of the sheet P (step S19).

Thereafter, the control unit 8 detects the switching of the output from each sheet sensor, and determines whether the remaining sheet has been removed, that is, whether the jam has been eliminated (step S21).

In step S21, the control unit 8 maintains the display on the operation panel 7 until the jam is cleared (step S21: No), and when the jam is cleared, there is no unprinted print job among the print jobs. (Step S21: Yes → step S23).

If it is determined in step S23 that there is nothing left to be printed, the control unit 8 ends the printing process (step S23: Yes), and if it is determined that something to be printed remains, the printing process is resumed. (Step S23: No → step S1).

On the other hand, when the control unit 8 determines that even a part of the sheet P remains on the conveyance belt 51 in step S5 (step S5: Yes), the control unit 8 further places the entire remaining sheet P on the conveyance belt 51. It is determined whether or not it is at a position existing at (step S7).

When the entire sheet P remains on the conveyance belt 51 in step S7 (step S7: Yes), the control unit 8 stops the conveyance by the conveyance belt 51. Further, the control unit 8 controls the elevation driving unit 45 to start lowering of the belt platen unit 43 in order to separate the distance between the belt platen 43 and the image forming unit 3 (step S9). The process of lowering the belt platen unit 43 corresponds to the separation process in the claims.

Then, the control unit 8 rotates the conveyance belt 51 in the conveyance direction to move the sheet P in order to convey the remaining sheet P to a position where it is easy to remove (step S11). This conveyance operation corresponds to the first post-jamming conveyance processing in the claims.

The first post-jamming conveyance process may be performed after the separation process is started, and it is not necessary to wait for the end of the separation process to start. That is, by performing the first post-jamming conveyance processing in parallel while the separation processing is being performed, the time taken to lead the sheet P to the position where it is easy to remove can be shortened, and the downtime of the image forming apparatus 100 can be reduced. It can be reduced.

The first post-jamming conveyance processing and separation processing will be described more specifically using FIG. When the control unit 8 detects a jam, the conveyance of the sheet P by each unit is stopped. At this time, as shown in FIG. 6A, the sheet P remains at the position where the entire sheet P is placed on the conveyance belt 51. Thereafter, the control unit 8 controls the elevation driving unit 45 to start the lowering of the belt platen unit 43 and then rotates the conveyance belt 51 of the conveyance unit 2 to start the first post-jamming conveyance processing. By conveying the sheet P by a predetermined distance by the first post-jamming conveyance processing, as shown in FIG. 6B, the sheet P is moved to a position (a separated position) where a part of the leading end of the remaining sheet P protrudes from the conveyance belt 51. It will be moved.

Here, the “predetermined distance” for transporting the sheet P by the transport belt 51 is the tip of the sheet P on the transport belt 51 based on the number of pulses output from the encoder 57 after the tip of the sheet P is detected by the sheet sensor 64b. Since the position is specified, the distance from the leading end position of the sheet P to the downstream end of the conveyance belt 51 is a length obtained by further adding a predetermined amount.

In addition, although the predetermined amount (the amount by which the leading end of the sheet P protrudes from the conveyance belt 51) may be uniform, it may be appropriately changed so that the sheet P can be easily removed. For example, when the size of the sheet P being conveyed is large, if the area on which the residual negative pressure acts on the sheet P is large, it is difficult for the user to remove it. You may

By carrying out the first post-jamming conveyance processing described in step S11, the conveyance of the sheet P is stopped at a position where the leading end side of the sheet P jumps (is separated) from above the conveyance belt 51. It becomes possible to easily remove the remaining paper P by picking up the popped out part, and conventionally, the paper P is subjected to the influence of the residual negative pressure by the suction fan 60 as shown in FIG. 6 (a). As a result, the problem of being adsorbed on the conveyance belt 51 and difficult to remove is solved.

After the control unit 8 causes the sheet P to be displaced to the state shown in FIG. 6B by driving the conveyance belt 51 and stops the conveyance by the conveyance unit 2, the user removes the sheet P via the operation panel 7. Ask for (step S19). Thereafter, the processing of step 19 and thereafter is executed.

On the other hand, when it is determined in step S7 that a part of the sheet P is at a position separated from the transport belt 51 when the jam occurs, the controller 8 controls the sheet P to be registered (step S7: No). It is determined whether or not the roller 41 and the transport belt 51 are in the straddling position (step S13). In step S13, the control unit 8 further determines whether the length of the sheet P present on the upstream side of the registration roller 41 is equal to or greater than a predetermined length (step S13).

Specifically, the control unit 8 specifies the position of the leading end of the sheet P based on the integrated pulse number output by the encoder 57 from the timing when the sheet sensor 46a detects the end of the sheet P, and this specified leading end position The rear end position of the sheet P is specified from the length in the conveyance direction of the sheet P being conveyed, and the length of the sheet P present upstream of the registration roller 41 is specified.

In step S13, when it is determined by control unit 8 that the predetermined length does not exist (step S13: No), control unit 8 stops all conveyance operations by conveyance belt 51 etc. 43 is lowered to notify the user to remove the jammed sheet (steps S17 and S19).

On the other hand, when it is determined by the control unit 8 that the rear end side of the sheet P remains on the upstream side of the registration roller 41 for a predetermined length or more (step S13: Yes) Run.

The second post-jamming conveyance processing will be described with reference to FIG.

When a jam is detected by the control unit 8, the sheet P is at the position shown in FIG. 7 (a). At this time, although the control unit 8 detects a jam, the conveyance operation by the registration roller 41 and the conveyance belt 51 is continued without stopping. However, the control unit 8 controls the conveyance of each part so that the conveyance speed is higher than that of the conveyance belt 51.

The conveyance control by the control unit 8 causes a speed difference between the registration roller 41 and the conveyance belt 51. As a result, as shown in FIG. 7B, slack is gradually formed on the sheet P.

When the control unit 8 continues the conveyance by the registration roller 41 and the conveyance belt 51 so that the slack formed on the sheet P is maintained, the slack moves to the downstream side in the conveyance direction as the sheet P is conveyed. As shown in FIG. 7 (c), it is pressed against the pressure roller 64.

The slack pressed against the pressing roller 64 is further transported downstream as the sheet P is transported, and is gradually crushed by being pinched by the pressing roller 64 and the transport belt 51. When the slack portion passes through the pressing roller 64, the slack is crushed and the sheet is broken as shown in FIG. 7 (d).

When the rear end of the sheet P passes through the pressing roller 64, the control unit 8 does not execute any of the conveyance operations of the registration roller 41 and the conveyance belt 51, that is, the conveyance of the registration roller 41 and the conveyance belt 51 is stopped. In this state, the second post-jamming conveyance processing ends.

Thereafter, the control unit 8 causes the elevating mechanism to lower the belt platen 43, prompts the user to remove the remaining sheet P via the operation panel unit 7 (step S19), and executes the processing of step 21 and subsequent steps.

In step S13, it is determined whether or not the sheet P has a "predetermined length" upstream of the registration roller 41. This "predetermined length" means that the sheet P shown in FIG. 7D is broken. It means the minimum required amount to produce.

As shown in FIG. 7D, the control unit 8 controls the conveyance speed of the sheet P by the registration roller 41 and the conveyance belt 51 to execute the second post-jamming conveyance processing on the sheet P as described above. In the sheet P, it is possible to form a fold in the direction orthogonal to the transport direction. Then, since the control unit 8 controls each portion to stop the conveyance of the sheet P on the conveyance belt 51 after intentionally causing the sheet P to be broken, the user pinches the broken portion This makes it possible to easily remove the sheet P remaining in the apparatus.

  As described above, in the image forming apparatus 100 according to the present invention, when the control unit 8 determines that the positions of the leading end and the trailing end of the sheet P are present on the conveyance belt 51 when detecting a jam, ie, When it is determined that the entire sheet P present directly under the image forming unit 3 is present in a state of being adsorbed by the conveyance belt 51, the conveyance unit 2 is controlled to perform the first post-jamming conveyance processing. The conveyance processing of the sheet P is performed such that a part of the leading end side of the sheet P in the conveyance direction is projected from the downstream end of the conveyance belt 51. Therefore, it is possible to intentionally create a portion on the leading end side of the sheet P from which the suction due to the residual negative pressure is released, and the user can easily use the protruding portion to easily make a recording medium remaining in the apparatus. It can be removed.

  In addition, when detecting a jam, the control unit 8 causes the lifting and lowering drive unit 45 to start the separation processing, and performs the first post-jamming conveyance processing while the separation processing is being performed. Here, since the first post-jamming conveyance processing is performed in parallel without waiting for the end of the separation processing, the time until the remaining recording medium is removed can be reduced, and the downtime of the apparatus can be reduced. It becomes possible.

Further, when the control unit 8 detects a jam, the sheet P exists at a position straddling the registration roller 41 and the conveyance belt 51, and the sheet P having a predetermined length or more remains on the upstream side of the registration roller 41. If it is determined that the second jam occurs, the second post-jamming transport process is executed. In the second post-jamming conveyance processing, the conveyance belt 51 is driven at a lower speed than the registration rollers 41, so that the slack is formed on the sheet P, and the conveyance is continued and the formed slack is the pressing roller 64. It passes below and is crushed. As a result, it is possible to intentionally make the sheet P fold in a method orthogonal to the transport direction. Therefore, the user can easily remove the sheet P remaining in the apparatus by picking up and utilizing the broken portion.
(Other modifications)

  In the first embodiment, the ink jet method has been described as the image forming unit. However, the present invention is not limited to this, and any of an electrophotographic method, a stencil method and the like can be applied.

Further, as a means for bringing the recording medium into close contact with the conveyance belt immediately below the image forming means, the suction method has been described. However, the present invention is not limited to this, and is applicable as long as the conveyance belt and the recording medium continue to be in a close contact state even after the driving is stopped. For example, JP-A-2008-156049 disclosed by the present applicant, and JP-A-2004-90533, JP-A-2000-247476, and JP-A-2000-247476 described as prior art documents in the publication. The electrostatic conveyance system described in the 2003-103857 gazette etc. is mentioned. In addition, the thing in which close_contact | adherence states, such as a residual negative pressure demonstrated in this specification, continue shall be collectively called a residual adsorption.

Further, in the second post-jamming conveyance processing, the control unit 8 has been described as continuing the conveyance processing of the conveyance belt 51 and the registration roller 41 after jam detection. However, it is not limited to this mode, as long as slack can be formed in the sheet P and the slack can be crushed by the pressing roller 64 to cause the sheet P to break. For example, since slack can be formed on the sheet P by the conveyance of the registration roller 41 by stopping only conveyance of the conveyance belt 51 after jam detection, the conveyance belt 51 can be redriven after formation of the slack. Also good. Further, after the jam detection, the conveyance operation of both the registration roller 41 and the conveyance belt 51 may be stopped, and thereafter, the sheet P may be slackened by being redriven. At this time, a difference in conveyance speed may be provided between the registration roller 41 and the conveyance belt 51 to form a slack, or the registration belt 41 may be driven first and then the conveyance belt may be driven later. Sag may be formed. In short, it is only required that the conveyance amount within the predetermined period is longer for the registration roller 41 than for the conveyance belt 51. Needless to say, in the case where the inkjet head 66 is used as an image forming unit, it is necessary to prevent the slack formed on the sheet P from colliding with the inkjet head 66.

Thus, it is a matter of course that the invention includes various embodiments that are not described herein. Accordingly, the technical scope of the present invention is defined only by the invention-specifying matters according to the scope of claims appropriate from the above description.

Further, when the present invention is expressed as a higher-level concept, the image forming unit 3 that forms an image on the recording medium P and the image forming unit 3 disposed immediately under the image forming unit 3 contact the recording medium P on the conveyance belt 51. Based on the conveyance unit 2 conveyed to the conveyance direction downstream side, one or more detection units that detect the position of the recording medium P, and information from the detection unit and the conveyance amount by the conveyance unit 2, the occurrence of jamming is determined. The control unit 8 identifies the position of the recording medium P on the transport belt 51 when it is determined that a jam has occurred, and the control unit 8 determines a predetermined jam according to the position of the recording medium P identified when the jam occurs. The image forming apparatus 100 is characterized in that the post-conveying process is performed.

DESCRIPTION OF SYMBOLS 1 paper feed unit 2 conveyance unit 3 image forming unit 4 top conveyance unit 5 discharge unit 6 reverse unit 7 operation panel 8 control unit 43 belt platen unit 44 head unit 45 lifting unit 51 conveyance belt 51 a conveyance surface 52 drive roller 53 to 5 55 driven roller 56 belt platen motor 57 encoder 58 plastic template 59 chamber 60 fan 61 belt hole 62 recessed portion 63 through hole 64 pressure roller 66 inkjet head 67 head holder 100 image forming apparatus

Claims (3)

An image forming unit that forms an image on a recording medium;
A conveyance unit disposed immediately below the image forming unit for bringing the recording medium into close contact with the conveyance belt and conveying the recording medium to the downstream side in the conveyance direction;
One or more detection units for detecting the position of the recording medium;
A control unit that determines the occurrence of a jam from the information from the detection unit and the transport amount by the transport unit, and identifies the position of the recording medium on the transport belt when it is determined that a jam occurs Equipped
When the control unit determines that the positions of the leading end and the trailing end of the recording medium specified at the time of jam occurrence are present on the conveyance belt, a part of the leading end side of the recording medium in the conveyance direction is from the conveyance belt end An image forming apparatus, comprising: performing a first post-jamming conveyance process for causing the conveyance unit to convey the recording medium to a position where the recording medium is ejected. The image processing apparatus further includes an adjustment unit that adjusts a distance between the image forming unit and the conveyance unit.
The control unit, when detecting the jam, causes the adjustment unit to start separation processing for separating the distance, and executes the first post-jump conveyance processing while the separation processing is being performed. The image forming apparatus according to claim 1. A registration roller that supplies the recording medium to the conveyance unit;
The upstream end of the conveyance belt further includes a pressing roller for pressing the recording medium onto the conveyance belt.
When the control unit detects the jam, the recording medium exists at a position straddling the registration roller and the conveyance belt, and the rear end portion of the recording medium is upstream of the position of the registration roller If it is determined that the recording medium is located at a predetermined length or longer, the drive of the conveyance belt and the registration roller is controlled to form a slack in the recording medium, and the trailing edge of the recording medium passes the pressing roller. The image forming apparatus according to claim 1, wherein a second post-jamming conveyance process is performed to control conveyance of the recording medium so that the slack is crushed.