JP2019099380A - Transport device, image formation device, transport method and image formation method - Google Patents

Abstract

To transport a medium to be transported accurately to a target position at a prescribed timing in a configuration in which, a position of the medium to be transported can be changed multiple times in transport.SOLUTION: A transport device comprises: position detection means 101-103 for detecting a position of a side end part Pa of a medium P to be transported; and position change means 31 for transporting the medium P to be transported according to a position where the medium P to be transported is detected by the position detection means 101-103, and changing a position of the medium P to be transported multiple times by driving in at least one of a width direction of the medium to be transported and a rotation direction in a transport plane of the medium to be transported, and the device further comprises a transport speed control part 23 for changing transport speed of the medium P to be transported according to a changed position of the medium P to be transported by the position change means 31.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a transport apparatus for transporting a medium to be transported, an image forming apparatus provided with the transport apparatus, a transport method for transporting a medium to be transported, and an image forming method using the transport method.

  As a conveying apparatus for conveying a medium to be conveyed, for example, a conveying apparatus for conveying a sheet such as a sheet or an original in an image forming apparatus such as a copying machine or a printer is known.

  Conventionally, in this type of conveyance apparatus, when conveying a sheet to an image forming unit or an image transfer unit, the sheet conveyed is abutted against the nip of a stopping conveyance roller pair to correct the skew of the sheet. Thereafter, the sheet is conveyed to the target position by starting the rotation of the conveying roller pair at a predetermined timing. However, the method in which the sheet is abutted against the nip of the transport roller pair has a problem that productivity (image forming speed) is reduced because the sheet is temporarily stopped.

  With respect to such problems, in Patent Document 1 (Japanese Patent Laid-Open No. 2005-53646), in order to be able to correct positional deviation such as skewing of a sheet without reducing productivity, a conveyance roller is conveyed while conveying the sheet. There has been proposed a conveying device which corrects the positional deviation without stopping the sheet by driving the pair in the direction opposite to the positional deviation direction of the sheet.

  Specifically, in the conveyance device described in Patent Document 1, as shown in FIG. 26, a pair of skew detection sensors 700 arranged in a direction orthogonal to the conveyance direction of the sheet 900 (the direction indicated by the dashed dotted line O). The leading end of the sheet 900 is detected, and the skew amount θ of the sheet 900 is calculated based on the detection result. Then, as shown in FIG. 27, the positional deviation (slant) of the sheet 900 is corrected by inclining the transport roller pair (resist roller pair) 800 according to the calculated skew amount θ.

  By the way, if the positional deviation of the sheet is corrected while conveying the sheet as described above, the leading end position of the sheet changes, so the time until the leading end of the sheet reaches a predetermined target position changes. Therefore, when the sheet is conveyed at a conveyance speed set in advance, the timing at which the sheet reaches the target position is deviated, and a problem arises that the sheet can not be conveyed with high accuracy.

  Therefore, in the conveyance device described in Patent Document 1, in order to eliminate the shift of the sheet arrival timing due to the positional shift correction of the sheet, the sheet leading end position after the positional shift correction is calculated from the positional shift amount of the sheet and the calculation. Adjustment of the sheet conveyance speed is performed based on the result.

  However, in the conveyance device described in Patent Document 1, it is not possible to detect the skew of the sheet after the leading edge of the sheet passes the skew detection sensor. That is, skew detection can be performed only once for one sheet. Accordingly, since the positional deviation correction of the sheet can be performed only once, there is a problem that the sheet can not be conveyed with high accuracy when the positional deviation of the sheet occurs after the positional deviation correction.

  In order to solve the above problems, the present invention relates to a position detection means for detecting the position of the side end portion of the medium to be conveyed, and the medium to be conveyed according to the position detected by the position detection means by the position detection means. A position changing unit configured to drive the medium to be conveyed in a plurality of times by driving in at least one of the width direction of the medium to be conveyed and the rotation direction in the medium conveyance surface while conveying And a transport speed control unit that varies the transport speed of the medium to be transported according to the position of the medium to be transported after the change by the position changing unit.

  According to the present invention, the position detection means detects the position of the medium to be conveyed, changes the position of the medium to be conveyed a plurality of times accordingly, and changes the conveyance speed accordingly. It becomes possible to transport the medium accurately and reliably at the target transport timing.

FIG. 1 is a schematic configuration diagram of an ink jet image forming apparatus according to an embodiment of the present invention. It is a top view of the conveyance device concerning this embodiment. It is a side view of a drive mechanism which drives a pinching roller pair. It is a top view of a drive mechanism which drives a pinching roller pair. (A) shows a state in which the holding frame has moved only in the width direction, (b) shows a state in which the holding frame has moved only in the rotation direction in the sheet conveyance surface, (c) shows the holding frame in the width direction FIG. 12 is a diagram showing a state of movement in both directions of rotation in the sheet conveyance surface and the sheet conveyance surface. It is a block diagram showing a control system of a conveyance device concerning this embodiment. It is a figure which shows the method of calculating misregistration amount from the positional infomation on the paper obtained using two CIS. It is a figure for demonstrating the positional offset amount of the width direction. It is a figure which shows a motion of the conveyance apparatus which concerns on this embodiment, Comprising: (a) is a top view, (b) is a side view. It is a figure which shows a motion of the conveyance apparatus which concerns on this embodiment, Comprising: (a) is a top view, (b) is a side view. It is a figure which shows a motion of the conveyance apparatus which concerns on this embodiment, Comprising: (a) is a top view, (b) is a side view. It is a figure which shows a motion of the conveyance apparatus which concerns on this embodiment, Comprising: (a) is a top view, (b) is a side view. It is a figure which shows a motion of the conveyance apparatus which concerns on this embodiment, Comprising: (a) is a top view, (b) is a side view. It is a figure which shows a motion of the conveyance apparatus which concerns on this embodiment, Comprising: (a) is a top view, (b) is a side view. It is a figure which shows the flowchart of the conveying apparatus which concerns on this embodiment. It is a figure which shows the flowchart of the conveyance speed control method. FIG. 7 is a diagram for describing a method of calculating a positional change amount of a sheet accompanying positional deviation correction. It is a block diagram which shows the control system of the conveying apparatus which concerns on other embodiment. It is a figure which shows the flowchart of the conveying apparatus which concerns on other embodiment. It is a block diagram which shows the control system of the conveying apparatus which concerns on another embodiment. FIG. 7 is a flowchart of a transport apparatus according to another embodiment. It is a block diagram which shows the control system of the conveying apparatus which concerns on another embodiment. It is a figure which shows the flowchart of the conveying apparatus which concerns on another embodiment. FIG. 1 is a view showing an example in which a conveyance device according to the present invention is applied to an electrophotographic image forming apparatus. It is a figure which shows the example which applied the conveying apparatus which concerns on this invention to a post-processing apparatus. It is a top view of the conventional conveyance device. It is a top view of the conventional conveyance device.

  Hereinafter, the present invention will be described based on the attached drawings. In each drawing for explaining the present invention, components such as members or components having the same function or shape are denoted by the same reference numerals as long as discrimination is possible, and then the explanation thereof will be described. I omit it.

  FIG. 1 is a schematic block diagram of an ink jet image forming apparatus according to an embodiment of the present invention.

[overall structure]
The ink jet image forming apparatus 100 according to the present embodiment mainly includes a sheet feeding unit 1, an image forming unit 2, a drying unit 3, and a sheet discharging unit 4. In the inkjet type image forming apparatus 100, the image forming unit 2 forms an image on a sheet P as a sheet supplied from the sheet feeding unit 1 using ink which is a liquid for image formation. Then, after the ink adhering to the sheet P is dried in the drying unit 3, the sheet P is discharged from the sheet discharge unit 4. When duplex printing is performed, an image is formed on the front side of the sheet P in the image forming unit 2, and then drying processing is performed in the drying unit 3, and the sheet P is conveyed to the reverse conveyance path 150 without being discharged. Do. The sheet P is again supplied to the image forming unit 2 in a state of being turned upside down by passing through the reverse conveyance path 150, and after the image is formed on the back side of the sheet P in the image forming unit 2, the drying unit Drying processing is performed in 3 and the sheet is discharged from the sheet discharge unit 4.

[Paper Feeder]
The sheet feeding unit 1 mainly includes a sheet feeding tray 5 on which a plurality of sheets P are stacked, a feeding device 6 that separates the sheets P from the sheet feeding tray 5 one by one, and an image forming portion 2 and a conveying device 7 for feeding the same. As the feeding device 6, it is possible to use any feeding device such as a device using a roller or a roller or a device using air suction. The sheet P fed from the sheet feeding tray 5 by the feeding device 6 is conveyed to the image forming unit 2 by the conveying device 7.

[Image formation unit]
The image forming unit 2 mainly uses a transfer drum 8 as a first conveyance rotating body that receives the fed sheet P and transfers it to the sheet holding drum 9, and the sheet P transferred by the transfer drum 8 on the outer peripheral surface. A sheet carrying drum 9 as a second conveying rotating body for carrying and carrying, an ink discharge unit 10 for discharging ink toward the sheet P carried on the sheet carrying drum 9, and a sheet carrying drum 9 A transfer drum 11 is provided as a third conveyance rotating body for transferring the sheet P to the drying unit 3.

  The leading end of the sheet P conveyed from the sheet feeding unit 1 to the image forming unit 2 is held by a swingable gripper 16 as a holding unit provided on the surface of the transfer cylinder 8, and the surface movement of the transfer cylinder 8 is performed. It is transported along with it. The sheet P conveyed by the transfer cylinder 8 is delivered to the sheet holding drum 9 at a position opposite to the sheet holding drum 9.

  A similar gripper is provided on the surface of the sheet carrying drum 9 as a gripping portion, and the leading end of the sheet is gripped by the gripper. Further, a plurality of suction holes are dispersedly formed on the surface of the sheet carrying drum 9, and a suction air flow toward the inside of the sheet carrying drum 9 is generated in each suction hole by the suction device 12. The leading end of the sheet P delivered from the transfer cylinder 8 to the sheet holding drum 9 is gripped by the gripper, and is attracted to the surface of the sheet holding drum 9 by the suction air flow, and along with the surface movement of the sheet holding drum 9. It is transported.

  The ink ejection unit 10 according to the present embodiment ejects four color inks of C (cyan), M (magenta), Y (yellow), and K (black) to form an image, and for each ink The individual liquid discharge heads 10C, 10M, 10Y and 10K are provided. The configuration of the liquid ejection heads 10C, 10M, 10Y, and 10K is not limited as long as it ejects a liquid, and any configuration can be adopted. If necessary, a liquid ejection head that ejects a special ink such as white, gold, or silver may be provided, or a liquid ejection head that ejects a liquid that does not constitute an image, such as a surface coating liquid, may be provided.

  The liquid ejection heads 10C, 10M, 10Y, and 10K of the ink ejection unit 10 each control the ejection operation according to the drive signal corresponding to the image information. When the sheet P carried on the sheet carrying drum 9 passes through the area facing the ink ejection unit 10, the ink of each color is ejected from the liquid ejection heads 10C, 10M, 10Y and 10K, and an image corresponding to the image information is displayed. It is formed. In the present embodiment, as long as the image forming unit 2 deposits a liquid on the sheet P to form an image, the configuration thereof is not limited.

[Drying section]
The drying unit 3 mainly includes a drying mechanism 13 for drying the ink deposited on the sheet P in the image forming unit 2 and a transport mechanism 14 for transporting the sheet P transported from the image forming unit 2. It is done. After the sheet P conveyed from the image forming unit 2 is received by the conveyance mechanism 14, the sheet P is conveyed so as to pass through the drying mechanism 13, and is delivered to the paper discharge unit 4. When passing through the drying mechanism 13, the ink on the sheet P is subjected to a drying process, whereby the liquid such as water in the ink evaporates, the ink is fixed on the sheet P, and the sheet P curls. Be suppressed.

[Paper output unit]
The paper discharge unit 4 mainly includes a paper discharge tray 15 on which a plurality of sheets P are stacked. The sheets P conveyed from the drying unit 3 are sequentially stacked and held on the sheet discharge tray 15. In the present embodiment, as long as the sheet discharge unit 4 discharges the sheet P, the configuration thereof is not limited.

[Other additional function part]
The ink jet type image forming apparatus 100 according to the present embodiment includes the sheet feeding unit 1, the image forming unit 2, the drying unit 3, and the sheet discharging unit 4, but other functional units may be added as appropriate. For example, after adding a pre-processing unit that performs pre-processing for image formation between the paper feeding unit 1 and the image forming unit 2 or after performing post-processing of image formation between the drying unit 3 and the paper discharge unit 4 A processing unit can be added.

  Examples of the pretreatment unit include one that performs a treatment liquid application treatment that applies a treatment liquid for reacting with the ink to suppress bleeding on the paper P, but the content of the pretreatment is not particularly limited. . Further, as the post-processing unit, for example, a sheet inverting conveyance process for inverting the sheet P on which the image is formed by the image forming section 2 and sending it to the image forming section 2 again to form an image on both sides of the sheet P A process of binding a plurality of sheets of paper P on which an image is formed may, for example, be mentioned, but the content of the post-processing is not particularly limited.

  The “image” formed on the sheet is not limited to one in which significant images such as characters and figures are visualized, and includes, for example, patterns that do not have their own meaning. In addition, the “sheet” on which the image is formed is not limited in the material, and it is possible to temporarily attach a liquid, such as paper, yarn, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. What is necessary is just a thing, for example, may be used for textile products, such as a film product, clothing materials, building materials, such as a wallpaper and a floor material, leather products, etc. The “liquid” is not particularly limited as long as it has a viscosity and surface tension that can be discharged from the head, but the viscosity is 30 mPa · s or less at normal temperature and normal pressure, or by heating and cooling. Is preferred. More specifically, solvents such as water and organic solvents, colorants such as dyes and pigments, polymerizable compounds, functionalizing materials such as resins and surfactants, and biocompatible materials such as DNA, amino acids, proteins and calcium Solutions, suspensions, emulsions and the like containing edible materials such as natural pigments and the like, and these can be used in applications such as ink jet inks and surface treatment liquids.

  Further, the “inkjet type image forming apparatus” includes an apparatus in which the liquid discharge head and the sheet material move relative to each other, but is not limited thereto. Specific examples include a serial type device that moves the liquid discharge head, a line type device that does not move the liquid discharge head, and the like.

  The “liquid discharge head” is a functional component that discharges and discharges a liquid from a discharge hole (nozzle). Discharge of a piezoelectric actuator (laminated piezoelectric element and thin film piezoelectric element), a thermal actuator using an electrothermal transducer such as a heating resistor, or an electrostatic actuator consisting of a diaphragm and an opposing electrode as an energy generation source for discharging a liquid Although energy generation means can be used, the discharge energy generation means used is not limited.

  Subsequently, the conveyance device 7 provided in the sheet feeding unit 1 according to the present embodiment will be described.

  FIG. 2 is a plan view of the transfer device according to the present embodiment.

  As shown in FIG. 2, the conveyance device 7 includes three CISs 101 to 102 as position detection means for detecting the position of the sheet P, and two leading edge detection sensors as conveyance timing detection means for detecting the conveyance timing of the sheet P. 200, 220, and a pinching roller pair 31 as position changing means for changing the position of the sheet P while holding (sandwiching) the sheet P being conveyed. In the following description, the plurality of CISs 101 to 103 are, in order from the upstream side in the sheet conveyance direction, a first CIS (first position detection means) 101, a second CIS (second position detection means) 102, a third The CIS (third position detection means) 103 will be referred to. Further, among the two front end detection sensors 200 and 220, the front end detection sensor 200 disposed on the downstream side of the nipping roller pair 31 is referred to as a downstream end front end detection sensor (first transport timing detection means). The front end detection sensor 220 disposed on the upstream side is referred to as an upstream side front end detection sensor (second transport timing detection means).

  In recent years, CIS uses a small light emitting diode (LED) as a light source to miniaturize the device, and a contact image sensor (Contact Image Sensor) that reads an image directly with a linear sensor through a lens. Sensor) is called. Each of the CISs 101 to 103 can detect a side edge Pa on one end side of the sheet P in the width direction by a plurality of line sensors provided in the width direction of the sheet P. The first CIS 101 and the second CIS 102 are disposed on the upstream side of the pinch roller pair 31 and on the downstream side of the transport roller pair 44 that is one upstream side of the pinch roller pair 31. On the other hand, the third CIS 103 is disposed downstream of the pinch roller pair 31 and upstream of the transfer drum 8. Each of the CISs 101 to 103 is disposed in parallel to the width direction of the sheet P (direction orthogonal to the transport direction).

  Each tip detection sensor 200, 220 is configured of a reflective optical sensor or the like. The upstream tip detection sensor 220 is disposed upstream of the pinch roller pair 31 and downstream of the second CIS 102. The downstream tip detection sensor 200 is disposed downstream of the pinch roller pair 31 and upstream of the third CIS 103. When the sheet P is conveyed, the leading end portion Pb of the sheet P is detected by the upstream side leading end detection sensor 220, whereby the conveyance timing when the leading end portion Pb of the sheet P reaches the upstream side leading end detection sensor 220 is detected. Ru. Further, after the sheet P is nipped by the nipping roller pair 31, when the leading end Pb of the sheet P reaches the position of the downstream side leading end detection sensor 200, the leading end Pb of the sheet P is detected by the downstream side leading end detection sensor 200 The transport timing at which the leading end portion Pb of the sheet P reaches the downstream side leading end detection sensor 200 is detected.

  The pinching roller pair 31 moves in the width direction (direction of arrow S in FIG. 2) of the sheet P while pinching the sheet P being conveyed, or in the sheet conveyance plane around the support shaft 73 (in FIG. Rotation in the direction of arrow W) to change the position of the paper P. As a result, the positional deviation α in the width direction of the sheet P and the positional deviation β in oblique feeding are corrected. In other words, the pinching roller pair 31 functions as a positional deviation correction unit that corrects the positional deviation of the sheet P. In the present embodiment, the support shaft 73 is provided on one axial end side of the holding roller pair 31, but the support shaft 73 may be provided at the axial center position of the holding roller pair 31.

  3 and 4 show the configuration of a drive mechanism for driving the pinch roller pair. FIG. 3 is a side view of the drive mechanism, and FIG. 4 is a plan view of the drive mechanism.

  As shown in FIG. 3, the pinching roller pair 31 is composed of a driving roller 31a that is rotationally driven about the roller axis and a driven roller 31b that is driven to rotate with the driving roller 31a. The holding roller pairs 31 are rotatably held around the roller axis by a holding frame 72 as a holding member. The holding frame 72 is supported by a base frame 71 fixed to the body frame 70 of the image forming apparatus.

  As shown in FIG. 4, the holding frame 72 is provided on the base frame 71 via a free bearing (ball transfer) 95 as a relay supporting member. Thus, the holding frame 72 is configured to be movable along the upper surface of the base frame 71 in any direction within the sheet conveyance surface (the conveyed medium conveyance surface). Thus, by supporting the holding frame 72 using the free bearing 95, it is possible to extremely reduce the friction load when the holding frame 72 moves. For this reason, it is possible to perform the positional deviation correction of the sheet to be described later at high speed and with high accuracy. In the present embodiment, the holding frame 72 is supported by the four free bearings 95, but the number of the free bearings 95 may be three or more.

  Further, as shown in FIG. 3, in the holding frame 72, the support shaft 73, which is the center of rotation in the sheet conveyance surface of the pinch roller pair 31, is provided so as to extend downward. The lower end portion of the support shaft 73 is inserted into the width direction guide portion 71 a formed in the base frame 71. The width direction guide portion 71a is a hole portion formed so as to extend substantially linearly in the width direction (the direction of the arrow S in FIG. 4). Further, a guide roller 79 is rotatably provided at the lower end portion of the support shaft 73, and the support shaft 73 is inserted via the guide roller 79 so as to be in contact with the width direction guide portion 71a. As the support shaft 73 moves in the width direction along the width direction guide portion 71a, the holding frame 72 and the pinching roller pair 31 held by the same also move in the width direction. The holding frame 72 is also configured to rotate around the support shaft 73 in the sheet conveyance surface (in the direction of the arrow W in FIG. 4). As the holding frame 72 rotates about the support shaft 73, the pinching roller pair 31 rotates in the sheet conveyance surface.

  As shown in FIG. 3, a conveyance drive motor (conveyance drive means) 61 which applies a driving force for conveying a sheet to the holding roller pair 31 on a bracket 69 provided on the right end side of the main body frame 70 in the figure. Is provided. The conveyance drive motor 61 and the drive roller 31 a of the pinch roller pair 31 are connected via a gear train composed of a plurality of gears 66 and 67 and a coupling mechanism 65. The coupling mechanism 65 can maintain the connection so that the driving force can be transmitted even if the rotation shaft of the drive roller 31 a and the rotation shaft of the gear 67 axially separate or approach each other in the axial direction, or drive in a direction inclined to each other. Is a two-step spline coupling. Thus, the drive roller 31a and the gear 67 are connected via the coupling mechanism 65, so that the pinch roller pair 31 moves in the width direction or rotates in the sheet conveyance surface, and the drive roller 31a is rotated. Even when the relative position between the transport drive motor 61 and the transport drive motor 61 changes, the drive power can be favorably transmitted from the transport drive motor 61 to the drive roller 31a.

  In addition, as shown in FIG. 3, at the end of the drive roller 31 a (the end opposite to the conveyance drive motor 61), the rotation for detecting the conveyance rotational speed of the drive roller 31 a (or conveyance drive motor 61) A rotary encoder 96 as a speed detection means is provided. The conveyance rotational speed of the pinching roller pair 31 is controlled based on the detection result of the rotary encoder 96.

  Further, the conveyance device 7 according to the present embodiment includes the width direction drive mechanism 38 for moving the holding frame 72 and the pinch roller pair 31 in the width direction, and the skew for rotating the holding frame 72 and the pinch roller pair 31 in the sheet conveyance surface. A row direction drive mechanism 39 is provided.

  As shown in FIGS. 3 and 4, the width direction drive mechanism 38 is configured by a width direction drive motor (width direction drive means) 62, a timing belt 97, a cam 45, a tension spring 59, and the like. The tension spring 59 is connected to the holding frame 72 and the base frame 71 so as to bias the holding frame 72 in one width direction (left direction in FIG. 4). The cam 45 is provided on the base frame 71 so as to be rotatable about its rotation axis 45 a. Further, the cam 45 is held in contact with the cam follower 46 provided on the support shaft 73 by the biasing force of the tension spring 59. When the cam 45 rotates, the cam follower 46 is pushed against the biasing force of the tension spring 59, whereby the holding frame 72 moves in the width direction (the right direction in FIG. 4).

  Further, as shown in FIG. 3, a timing belt 97 is stretched around the rotation shaft 45 a of the cam 45 and the motor shaft of the width direction drive motor 62. Thus, the driving force is transmitted from the width direction drive motor 62 to the cam 45 via the timing belt 97. Further, on the rotation shaft 45 a of the cam 45, a rotary encoder 57 as a rotation angle detection unit that detects a rotation angle (rotation amount) of the cam 45 is provided. By controlling the drive of the width direction drive motor 62 based on the detection result of the rotary encoder 57, the rotation angle of the cam 45 is controlled, and the amount of movement of the holding frame 72 in the width direction is adjusted. That is, the rotary encoder 57 functions as a drive position detection unit that detects the drive position when the holding frame 72 and the pinch roller pair 31 move in the width direction.

  As shown in FIGS. 3 and 4, the oblique direction drive mechanism 39 is constituted by an oblique direction drive motor (an oblique direction drive means) 63, a timing belt 98, a cam 47, a tension spring 60, a lever member 50 and the like. ing. The tension spring 60 is connected to the holding frame 72 and the base frame 71 so as to bias the holding frame 72 in one direction in the oblique direction (clockwise around the support shaft 73 in FIG. 4). The cam 47 is provided on the base frame 71 so as to be rotatable about its rotation axis 47a. The cam 47 is held in contact with a cam follower 48 provided at one end of the lever member 50 by the biasing force of the tension spring 60. Further, at the opposite end of the lever member 50, an action roller 49 is rotatably provided. The action roller 49 is held in contact with the projection 72 a provided on the holding frame 72 by the biasing force of the tension spring 60. With such a configuration, when the cam 47 rotates and the cam follower 48 is pressed by the cam 47, the lever member 50 rotates about the rotation shaft 50a. Along with this, the action roller 49 provided on the lever member 50 pushes the projection 72a of the holding frame 72 against the urging force of the tension spring 60, whereby the holding frame 72 is in the sheet conveyance surface (FIG. Anticlockwise rotation).

  Further, as shown in FIG. 3, a timing belt 98 is stretched around the rotation shaft 47 a of the cam 47 and the motor shaft of the oblique direction drive motor 63. As a result, the driving force is transmitted from the oblique direction drive motor 63 to the cam 47 via the timing belt 98. Further, on the rotation shaft 47 a of the cam 47, a rotary encoder 58 as a rotation angle detection means for detecting the rotation angle (rotation amount) of the cam 47 is provided. By controlling the drive of the oblique direction drive motor 63 based on the detection result of the rotary encoder 58, the rotation angle of the cam 47 is controlled, and the amount of rotation of the holding frame 72 in the sheet conveyance surface is adjusted. That is, the rotary encoder 58 functions as a drive position detection unit that detects a drive position when the holding frame 72 and the pinch roller pair 31 rotate in the sheet conveyance surface.

  5A shows a state in which only the cam 45 of the width direction drive mechanism 38 rotates and the holding frame 72 moves in the width direction, and FIG. 5B shows a skew direction drive mechanism as shown in FIG. Only the cams 47 of 39 rotate, and the holding frame 72 rotates in the sheet conveyance surface. FIG. 5C shows a state in which both the cams 45 and 47 rotate and the holding frame 72 moves in the width direction and also rotates in the sheet conveyance surface.

  Further, as shown in FIG. 3, the downstream tip detection sensor 200 is provided in the holding frame 72. Therefore, when the holding frame 72 moves in the width direction as described above or rotates in the sheet conveyance surface as described above, the downstream side front end detection sensor 200 is (integrally) integral with the holding frame 72 in the width direction or the sheet conveyance surface Move within. On the other hand, the upstream tip detection sensor 220 is fixed so as not to move on the transport path.

  FIG. 6 is a block diagram showing a control system of the transfer apparatus according to the present embodiment.

  As shown in FIG. 6, the conveyance device according to the present embodiment includes the conveyance drive motor 61 that applies a driving force for conveying the sheet to the pinch roller pair, and the width direction drive that drives the pinch roller pair in the width direction. A control unit 20 is provided to independently control each of the motor 62 and the skew direction drive motor 63 for rotating the pinch roller pair in the sheet conveyance surface. That is, the control unit 20 controls the conveyance rotation speed, the movement amount in the width direction, and the rotation amount in the sheet conveyance surface of the pinch roller pair.

  The control unit 20 calculates a positional displacement amount of the sheet based on the detection results of the CISs 101 to 103, a detection result of the downstream side leading end detection sensor 200, and a home position provided on the transfer drum 8. Based on the detection result of the sensor 80 (see FIG. 1), the target conveyance timing calculation unit 22 that calculates the target conveyance timing of the sheet to the predetermined target position, and the conveyance speed of the sheet And a conveyance speed control unit 23 for controlling the conveyance rotation speed of the pinching roller pair 31. Further, the transport speed control unit 23 detects information on the rotary encoder 96 that detects the transport rotational speed of the pinch roller pair 31, and each rotary that detects the amount of movement of the pinch roller pair 31 in the width direction and the amount of rotation in the sheet transport surface. The transport speed is also corrected based on the information of the encoders 57 and 58.

  In the present embodiment, the sheet P is held at the sheet gripping position A in synchronization with the timing at which the grippers 16 provided on the transfer drum 8 rotating at a constant speed reach the sheet gripping position A (see FIG. 1) on the transfer cylinder 8. It is required to reach the The timing when the gripper 16 reaches the sheet gripping position A can be specified by detecting the rotation reference position C of the transfer cylinder 8 by the home position sensor 80. Although only one gripper 16 is described in the example shown in FIG. 1, a plurality of grippers 16 may be provided on the transfer cylinder 8. Further, in the present embodiment, the sheet P is adjusted to the same speed each time at the target position B (see FIG. 1) slightly on the near side (upstream side) of the sheet gripping position A, and thereafter, the sheet gripping position is constant. It is transported to reach A. Therefore, in the present embodiment, the timing at which the sheet P reaches the target position B is set as the target transport timing. As described above, in the present embodiment, the speed adjustment completion position at which the conveyance speed of the sheet P is completed is set as the target position B, but the speed at which the sheet P is determined to the final target conveyance position such as the sheet gripping position A The final target transport position may be set as the target position B when the transport is not required. The target transport timing to be calculated may be, for example, the time from when the leading end portion Pb of the sheet P is detected by the downstream side leading end detection sensor 200 to when the sheet P reaches the target position B at a predetermined timing. Alternatively, the conveyance rotational speed of the pair of pinching rollers 31 may be such that the sheet P can reach the target position B in this time.

  Here, the method of calculating the sheet misregistration amount will be described with reference to FIGS. 7 and 8. Although FIG. 7 shows the method of calculating the sheet misregistration amount using the first CIS 101 and the second CIS 102, the sheet position using the second CIS 101 and the third CIS 103 is shown. The method of calculating the amount of deviation is the same.

  As shown in FIG. 7, when the leading end Pb of the sheet P passes through the first CIS 101 and reaches the second CIS 102, the positional deviation amount α of the sheet P in the width direction and the positional deviation amount β of skewing are It is detected.

  Specifically, the positional deviation amount α in the width direction is calculated based on the position in the width direction of the sheet P (the side end Pa in the width direction of the sheet P) detected by the second CIS 102. That is, the distance K1 in the width direction between the position in the width direction detected by the second CIS 102 and the conveyance reference position K becomes the positional deviation amount α in the width direction of the sheet P.

  In addition, the positional deviation β of skew feeding is calculated from the difference in the end position in the width direction of the sheet P detected by each of the first CIS 101 and the second CIS 102. That is, as shown in FIG. 7, when the leading end portion Pb of the sheet P reaches the second CIS 102, the distance K 1, K 2 in the width direction from the conveyance reference position K by the first CIS 101 and the second CIS 102. Is detected. Then, from these distances K1 and K2 and the distance M1 between the first CIS 101 and the second CIS 102 set in advance, skew feeding is performed using the formula of tan β = (K1-K2) / M1. An amount of positional deviation β of is calculated.

  In this manner, the positional deviation amount α in the width direction and the positional deviation amount β in oblique feeding are calculated. As shown in FIG. 8, when the sheet is moved from the position of P to the position of P ′ by performing misregistration correction of skew feeding, the amount of positional deviation in the width direction changes from α to α ′. Therefore, it is possible to perform more accurate positional deviation correction by calculating the positional deviation amount α ′ in the width direction in advance. However, the positional deviation amount α ′ in the width direction changes depending on which position is used as the basis for the positional deviation correction of skew feeding.

  Subsequently, the operation of the conveyance device according to the present embodiment will be described with reference to the plan views and the side views of FIGS. 9 to 14 and the flowchart of FIG. 15.

  As shown in FIGS. 9A and 9B, when the sheet P is conveyed, the pinch roller pair 31 is disposed at a home position where the roller axis is orthogonal to the conveyance direction (left and right direction in the drawing). ing. Further, in this state, the pinching roller pair 31 is separated from each other and stands by in a stationary state.

  Thereafter, as shown in FIGS. 10A and 10B, when the leading end Pb of the sheet P passes through the first CIS 101 and reaches the second CIS 102, the sheet is printed by the first CIS 101 and the second CIS 102. The “first position detection” is performed in which the position of the side end Pa of P is detected (S1 in FIG. 15). Then, based on the position information detected by the CIS 101 and 102, the position shift amount α in the width direction (or the position shift amount α ′ including the shift amount associated with the position shift correction of the skewing) and the position of the skewing The displacement amount β is calculated by the positional displacement amount calculation unit 21 (see FIG. 6). Then, based on the calculated positional displacement amount, the width direction drive motor 62 and the oblique direction drive motor 63 are controlled to move the nipping roller pair 31 in the width direction (in the direction of arrow S1 in FIG. 10) It is rotated in the conveyance plane (in the direction of arrow W1 in FIG. 10). As a result, a pick-up operation is performed to make the pinching roller pair 31 face the front end Pb of the sheet P (S2 in FIG. 15).

  Then, the leading end portion Pb of the sheet P is detected by the upstream side leading end detection sensor 220, and based on the detection timing, the pinching roller pair 31 contact each other and start conveyance rotation. Thereafter, as shown in FIGS. 11A and 11B, the sheet P is received by the pair of pinching rollers 31 facing each other, and the sheet P is conveyed while being pinched by the pinching roller pair 31. When the sheet P is delivered to the pinching roller pair 31, the conveyance roller pair 44 on the upstream side of the pinching roller pair 31 is separated from each other.

  Further, as shown in FIGS. 11A and 11B, when the sheet P is conveyed by the pinching roller pair 31 and the leading end Pb of the sheet P reaches the position of the downstream side leading end detection sensor 200, the downstream side leading end detection sensor The leading end portion Pb of the sheet P is detected by 200 (S3 in FIG. 15). Thus, the timing at which the leading end portion Pb of the sheet P reaches the downstream side leading end detection sensor 200 is detected. Then, based on the detection result of the downstream side front end detection sensor 200 and the detection result of the home position sensor 80 of the transfer cylinder 8, the target conveyance timing of the sheet to the predetermined target position B is the target conveyance timing calculation unit 22 (see FIG. 6) and are set (S4 in FIG. 15).

  Thereafter, as shown in FIGS. 12A and 12B, while conveying the sheet P by the pinching roller pair 31, the pinching roller pair 31 is in the direction opposite to the pick-up operation (arrow S2 direction and arrow W2 direction in the figure). (S5 in FIG. 15). Thereby, “first correction” is performed in which the positional deviation in the width direction of the sheet P and the positional deviation of the skew feeding are corrected.

  Further, as shown in FIGS. 13A and 13B, when the leading end Pb of the sheet P reaches the third CIS 103, the second CIS 102 and the third CIS 103 again cause the side edge Pa of the sheet P to The "second position detection" in which the position is detected is performed (S6 in FIG. 15). Then, based on the positional information detected by the CIS 102 and 103, the positional deviation amount in the width direction and the positional deviation amount for skewing are calculated by the positional deviation amount calculation unit 21. Then, the width direction drive motor 62 and the oblique direction drive motor 63 are controlled based on the calculated positional displacement amount, and the pinch roller pair 31 is in the width direction (in the direction of arrow S3 or in the direction of arrow S4 in FIG. 13). By moving the sheet P and rotating it within the sheet conveyance surface (in the direction of arrow W3 or in the direction of arrow W4 in FIG. 13), “second correction” is performed to correct the positional deviation of the sheet P (S7 in FIG. 15).

  Thus, even after the return operation (first correction), the positional deviation of the sheet P is detected (second position detection), and the positional deviation of the sheet P is corrected based on the detection result (second correction (second correction). The positional deviation that occurs while the sheet P is conveyed by the pinching roller pair 31 can be eliminated. In addition, positional deviation detection (second position detection) after such a return operation can be performed multiple times at predetermined intervals if the sheet is passing through the second CIS 102 and the third CIS 103. Therefore, the sheet can be transported with higher accuracy by performing such positional deviation detection (second position detection) a plurality of times and performing positional deviation correction (second correction) each time.

  However, if the position shift correction (second correction) as described above is performed after the return operation, the position in the sheet conveyance direction changes accordingly, and therefore, when the sheet is conveyed at the conveyance speed as it is, the sheet is conveyed. The timing of reaching the target position B changes. Therefore, in the present embodiment, when the positional deviation correction (second correction) is performed after the returning operation, each time the positional deviation correction is performed, it is based on the positional deviation correction amount (the position after the change of the sheet) of the sheet. The transport speed of the sheet P is changed (corrected) (S8 in FIG. 15). Then, the sheet P is conveyed further to the downstream side at the conveyance speed changed in this way, so that the timing at which the gripper 16 reaches the sheet gripping position A is matched as shown in FIGS. 14 (a) and 14 (b). Then, the sheet P is conveyed to the sheet gripping position A (S9 in FIG. 15). Then, when the sheet P reaches the sheet gripping position A, the nipping roller pair 31 is separated from each other, and the conveyance of the sheet by the nipping roller pair 31 ends. If there is no misalignment of the sheet after the return operation, and the misalignment correction (second correction) is not performed, the timing at which the paper reaches the target position B basically does not change, so the misalignment correction 2) There is no change in the corresponding transfer speed.

  Hereinafter, the control method of the transport speed will be described with reference to the flowchart of FIG.

  As shown in FIG. 16, when control of the nipping roller pair 31 is started, the gripper 16 is rotated based on the detection result of the home position sensor 80 of the transfer drum 8 before setting of the target transport timing is performed. It is confirmed that the user is at the reference position C (S11 in FIG. 16). Then, as described above, the leading end of the sheet is detected by the downstream side leading end detection sensor 200 (S12 in FIG. 16), and the target conveyance timing is based on the detection result and the detection result of the home position sensor 80 of the transfer cylinder 8 It is set (S13 in FIG. 16).

  The target rotational speed of the pinching roller pair 31 is calculated in accordance with the set target transport timing (S14 in FIG. 16). The calculation of the target rotational speed of the pinching roller pair 31 may be performed by the target conveyance timing calculation unit 22 or may be performed by another calculation unit. Then, the conveyance rotation speed of the pinch roller pair 31 is controlled based on the calculated target rotation speed (S15 in FIG. 16). In the present embodiment, the conveyance rotational speed of the pinching roller pair 31 is managed based on the signal from the rotary encoder 96 provided on the pinching roller pair 31. Therefore, in order to determine whether the conveyance rotational speed of the pinch roller pair 31 is faster or slower than the target rotational speed, the conveyance speed control unit 23 acquires a signal from the rotary encoder 96 (S16 in FIG. 16). .

  In addition, when misregistration correction (second correction) is performed by the nipping roller pair 31 after setting of the target conveyance timing, conveyance of the nipping roller pair 31 is performed based on the misregistration correction amount of the sheet accompanying the misregistration correction. Change the rotation speed. The misregistration correction amount corresponds to a drive position (drive amount and drive direction) at which the pinching roller pair 31 is driven in the width direction or in the rotation direction in the paper conveyance surface at the time of misregistration correction. Therefore, in the present embodiment, the conveyance speed control unit 23 acquires the signals from the rotary encoders 57 and 58 that detect the drive amount and the drive direction in the width direction of the pinch roller pair 31 and the sheet conveyance surface (see FIG. 16). S17). The target rotational speed for conveyance is changed based on the target conveyance timing and the signals from the rotary encoders 96, 57, 58 (S14 in FIG. 16). Then, the conveyance rotational speed of the pinching roller pair 31 is controlled based on the target rotational speed calculated again (S15 in FIG. 16). Then, the control of the transport rotational speed as described above is performed until the sheet transport time reaches the target transport timing (S18 in FIG. 16), and after the sheet transport time reaches the target transport timing, The sheet is transported to the sheet gripping position A at the same speed as the transport rotational speed (S19 in FIG. 16). Thus, the transport speed can be changed according to the misregistration correction amount of the sheet, and the sheet can be transported to the sheet gripping position A with high accuracy and high accuracy.

  A method of calculating the amount of positional change of the sheet accompanying the positional deviation correction will be described with reference to FIG.

  In FIG. 17, the point Z is the position of the rotation center (support shaft 73) in the sheet conveyance surface when the pinch roller pair 31 is disposed at the home position, the point R is the measurement reference point, and the point Q is The position of the leading end of the sheet when time t has elapsed since detection of the leading end of the sheet by the downstream side leading end detection sensor 200, point Q 'is misregistration correction at the timing (time t-1) just before time t. Indicates the position of the leading edge of the sheet when Further, in FIG. 17, the characters in parentheses are each point Z, Q, Q based on the measurement reference point R when the sheet conveyance direction is the X direction and the direction orthogonal to the sheet conveyance direction is the Y direction. It is X coordinate and Y coordinate of Q '. Is the inclination angle from the home position of the pinching roller pair 31 when the leading end of the sheet reaches the position of point Q (rotational angle in the sheet conveyance surface), and .theta. ' The tilt angle from the home position of the nipping roller pair 31 when it reaches the position of '(rotation angle in the sheet conveyance surface). Δθ is the difference between the inclination angles θ and θ ′.

  As described above, when the position of the leading end of the sheet P changes in accordance with the positional deviation correction operation, the position coordinates (Qx, Qy) of the sheet leading end position Q at time t can be calculated using Equations 1 and 2 below. Can be calculated.

Qx = cos (Δθ) (Qx′−Zx) −sin (Δθ) (Qy′−Zy)
+ Z x + X p ··· Equation 1
Qy = sin (Δθ) (Qx′−Zx) + cos (Δθ) (Qy′−Zy)
+ Zy + Yp + Ys ··· Equation 2

  Xp in the above equation 1 is an X-direction component of the transport distance by which the sheet P is transported to the timing immediately before time t (time t-1), and Yp in the above equation 2 is It is a Y direction component of conveyance distance. Assuming that the conveyance distance (the conveyance distance in the direction orthogonal to the roller axis) by which the sheet P is conveyed by the holding roller pair 31 during time t-1 is Fp, Xp and Yp are expressed by the following Expression 3 and Expression 4 be able to. Further, Ys in Expression 2 is the amount of movement in the width direction of the sheet P from the point Q ′ to the point Q (the amount of movement in the Y direction).

Xp = cos (θ ′) Fp ··· Equation 4
Yp = sin (θ ′) Fp Equation 5

  Therefore, by using the equations 1 to 4, it is possible to calculate the position coordinates (Qx, Qy) of the sheet front end position Q at time t.

  Then, by subtracting the X coordinate Vx of the leading end position of the sheet after the elapse of time t when the positional deviation correction is not performed from the calculated X coordinate Qx, the positional change amount G of the leading end of the sheet associated with the positional deviation correction Is calculated (see Equation 5 below). Then, by adjusting the transport speed to the target position based on the position change amount G calculated in this manner, the sheet can be transported to the target position at a predetermined transport timing.

  G = Qx-Vx ··· Equation 5

  As described above, according to the conveyance device of the present embodiment, the CIS that detects the position of the side edge of the sheet is used as the position detection unit that detects the position of the sheet, so that after the above-described return operation. As in the positional deviation correction (second correction), if the sheet is passing through the CIS, the CIS can detect the side edge of the sheet a plurality of times. As described above, by using the CIS, it is possible to detect the position of the sheet a plurality of times, so it is possible to detect the misregistration of the sheet which occurs every moment during the sheet conveyance, and the misregistration correction is high. Be able to do to the precision. In addition, even if the position in the sheet conveyance direction changes due to the position deviation correction, each time the position deviation correction is performed, the position deviation correction amount (the position of the sheet in the width direction and the rotation direction in the sheet conveyance surface) By changing the sheet conveyance speed based on the change amount), the sheet can be conveyed to the target position at a predetermined timing. That is, the positional change in the sheet conveyance direction due to multiple misregistration corrections is not collectively handled by changing the single transport speed, but the transport speed is changed each time misregistration correction is performed. Thus, the transfer speed can be adjusted with time allowance. As a result, it is possible to accurately transport the sheet with accuracy and in time for the target transport timing. As a result, the positional deviation of the image with respect to the sheet P can be prevented with high accuracy, and the printing quality is improved. Further, when performing double-sided printing, it is possible to correct the positional deviation of the image with respect to the front side and the back side, so it is possible to eliminate the relative positional deviation between the front side and the back side. . In the present embodiment, each time the position of the sheet is detected, the misregistration correction and the change of the transport speed are performed. However, a part of the position information of the sheet detected a plurality of times (two or more times) The positional deviation correction may be performed based on the detection result of the above, and the conveyance speed may be further changed. That is, the number of times of misregistration correction and the number of times of change of the transport speed may be smaller than the number of times that the position of the sheet is detected.

  By the way, in the present embodiment, the downstream side leading end detection sensor 200 is configured to be driven together (integrally) with the pinching roller pair 31, but the downstream side tip detection sensor 200 is jointly driven with the pinching roller pair 31. It is also possible to configure not to drive. However, in that case, the leading end detection position by the downstream side leading end detection sensor 200 differs according to the degree of skew of the sheet. Therefore, if the positional deviation of the sheet is corrected by the returning operation of the nipping roller pair 31 after detecting the leading end position of the sheet (first correction), the magnitude of the operation amount of the returning operation (the magnitude of the skew amount of the sheet) Accordingly, a change occurs in the target transport timing. Therefore, in order to eliminate the influence of such positional deviation correction operation (first correction), it is necessary to detect the sheet conveyance timing in the state where the return operation is completed.

  On the other hand, when the downstream side leading end detection sensor 200 is configured to be driven together with (integrally with) the pinching roller pair 31 as in the present embodiment, the downstream side leading end detection sensor 200 with respect to the sheet is Can be detected in the state of facing each time (with the same posture every time). As described above, since the front end detection position by the downstream side front end detection sensor 200 does not differ according to the degree of skew of the sheet, the target transport timing is not influenced by the dispersion of the front end detection position. Further, since the downstream side leading end detection sensor 200 is returned to the same position (home position) every time along with the return operation of the pinch roller pair 31, the distance from the downstream side front end detection sensor 200 to the target position B is also the same each time. . Therefore, there is no influence on the target transport timing due to the change of the distance from the downstream tip detection sensor 200 to the target position B.

  Thus, by driving the downstream side leading end detection sensor 200 together with the nipping roller pair 31, various influences in the case where the sensor is fixed can be prevented, and the return operation (first correction (first correction) It is not necessary to change the sheet transport speed in accordance with the above. Further, since the target transport timing is not influenced by the return operation, the transport timing can be detected before the return operation is completed (before the start of the return operation or in the middle of the return operation). Therefore, the target transport timing can be set at an early stage, the control time of the transport speed to be performed after that can be sufficiently secured, and the control accuracy is improved.

  In the present embodiment, the downstream side leading end detection sensor 200 is disposed on the downstream side of the pinching roller pair 31. However, in order to obtain an effect by driving the downstream side tip detection sensor 200 together with the pinching roller pair 31. Alternatively, the downstream side leading end detection sensor 200 may be disposed upstream of the pinching roller pair 31.

  Further, according to the present embodiment, it is not necessary to change the conveyance speed of the sheet accompanying the return operation, and therefore, the conveyance speed is only changed corresponding to only the positional deviation correction (second correction) after the return operation. It is good. Moreover, since the positional deviation correction (second correction) after the returning operation is a fine positional deviation correction performed after the positional deviation is once corrected, the change of the transport speed accompanying the correction operation is usually only slight. . Therefore, even when the sheet is transported at high speed or the transport distance to the target position is short, it is possible to sufficiently cope with the situation.

  Further, in the present embodiment, from the information of the rotary encoders 57 and 58 (drive position detection means) for detecting the positional deviation correction amount of the sheet, the amount of movement in the width direction of the pinch roller pair 31 and the amount of rotation in the sheet conveyance surface. Although it is indirectly obtained, it is also possible to calculate the misregistration correction amount of the sheet from the information of the CIS which directly detects the position of the sheet. However, since the CIS has a large amount of information and loads of communication and arithmetic processing increase, it is conceivable that the time from when the position of the sheet is detected to when the transport speed is changed may be long. On the other hand, in the case of indirectly calculating the misregistration correction amount of the sheet based on the information from the rotary encoder, since the load of communication and arithmetic processing is reduced, the change of the transport speed should be started at an early timing. Can. Therefore, even in the configuration in which the transport speed is high or the configuration in which the transport distance to the target position is short, the control time of the transport speed can be secured, and the sheet can be transported with high accuracy.

  A transport apparatus according to another embodiment of the present invention will be described based on FIGS. 18 and 19.

  In the transport apparatus according to the present embodiment, as compared with the transport apparatus according to the above-described embodiment, in FIG. 18, a rotary encoder 17 as rotational speed detection means for detecting the transport rotational speed of the transfer drum 8 is added. The only difference is that the step (S20) of receiving the signal from the rotary encoder 17 is added.

  The transfer cylinder 8 is basically controlled to rotate at a constant speed, but it is also conceivable that the transport rotational speed of the transfer cylinder 8 changes for some reason. In that case, as described above, even if the conveyance rotation speed of the pinch roller pair 31 is changed based on the misregistration correction amount of the sheet, the timing of the sheet and the gripper 16 on the transfer cylinder 8 may not match .

  Therefore, in the present embodiment, each rotary encoder detects a signal from the rotary encoder 96 that detects the conveyance rotational speed of the pinch roller pair 31, and detects the amount of movement of the pinch roller pair 31 in the width direction and the amount of rotation in the sheet conveyance surface. In addition to the signals from 57 and 58, the transport speed control unit 23 acquires the signal from the rotary encoder 17 of the transfer cylinder 8 (S16, S17, and S20 in FIG. 19), and these signals and the target transport timing The target rotational speed is changed based on (S14 in FIG. 19). Then, the conveyance rotation speed of the pinching roller pair 31 is controlled based on the target rotation speed calculated again (S15 in FIG. 19). As a result, even if the conveyance rotational speed of the transfer cylinder 8 changes, the timing of the sheet and the gripper 16 on the transfer cylinder 8 can be matched, and the sheet can be conveyed with higher accuracy.

  FIG. 20 and FIG. 21 are a block diagram and a flow chart of a transfer apparatus according to another embodiment different from the above-mentioned embodiment.

  In the embodiment shown in FIGS. 20 and 21, instead of the signal reception from the home position sensor 80 described above, the signal from the rotary encoder 17 of the transfer cylinder 8 is received in order to set the target transport timing. (S12 in FIG. 21). Other than that is the same as the embodiment shown in FIG. 18 and FIG. Even without the signal from the home position sensor 80, it is possible to confirm the position of the gripper 16 based on the signal from the rotary encoder 17 of the transfer cylinder 8. For this reason, in the present embodiment, based on the signal reception from the downstream side tip detection sensor 200 (S11 in FIG. 21) and the signal reception from the rotary encoder 17 of the transfer cylinder 8 thereafter (S12 in FIG. 21) The target transport timing is set (S13 in FIG. 21).

  22 and 23 are a block diagram and a flow chart of a transport apparatus according to yet another embodiment of the present invention.

  In the embodiments shown in FIG. 22 and FIG. 23, a laser Doppler velocimeter 18 is used as a medium speed detection means for directly detecting the sheet conveyance speed. The laser Doppler velocimeter 18 is a non-contact type measuring device that directly measures the transport speed of the medium to be transported (paper) using the Doppler effect of light.

  In the above-described embodiment, the conveyance speed of the sheet is indirectly detected by obtaining a signal from the rotary encoder 96 that detects the conveyance rotation speed of the pinching roller pair 31. However, if slippage occurs between the sheet and the pinch roller pair 31, there is a possibility that the transport speed of the pinch roller pair 31 obtained from the information of the rotary encoder 96 can not accurately detect the transport speed of the sheet. is there.

  Therefore, in the present embodiment, instead of the rotary encoder 96 that detects the conveyance rotational speed of the pinch roller pair 31, the conveyance rotational speed of the pinch roller pair 31 based on the sheet conveyance speed directly detected by the laser Doppler velocimeter 18. Are controlled (S20 in FIG. 23). That is, signals from the rotary encoders 57 and 58 for detecting the amount of movement in the width direction of the pinching roller pair 31 and the amount of rotation in the sheet conveyance surface, and the signal from the laser Doppler speed meter 18 (S17, S20 in FIG. 23) and change the target rotational speed based on these signals and the target transport timing (S14 in FIG. 23). Then, the conveyance rotation speed of the pinching roller pair 31 is controlled based on the target rotation speed calculated anew (S15 in FIG. 23). As a result, even if slippage occurs between the sheet and the pinching roller pair 31, it is possible to prevent the shift of the transport timing due to the slip, and to transport the sheet with higher accuracy.

  In the example using the laser Doppler velocimeter 18 as in the present embodiment, furthermore, as in the examples shown in FIGS. 18 and 19, based on the conveyance rotational speed of the transfer cylinder 8 detected by the rotary encoder 17. The transport speed may be changed. In that case, in addition to the prevention of the deviation of the conveyance timing due to the slip between the sheet and the pinch roller pair 31, the deviation of the conveyance timing due to the fluctuation of the conveyance rotational speed of the transfer cylinder 8 can also be prevented. It becomes possible to realize accurate transportation.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, Of course, a various change can be added in the range which does not deviate from the summary of this invention.

  In the above-described embodiment, the CIS is used as a position detection unit that detects the position of the side edge of the sheet, but not limited to the CIS, a plurality of photosensors such as a plurality of photosensors arranged along the width direction of the sheet may be used. Other detection means may be used as long as the side end can be detected.

  In the above embodiment, the case of correcting both the positional deviation in the width direction of the sheet and the positional deviation in oblique feeding is described as an example, but the conveying apparatus according to the present invention is not limited to the positional deviation in the width direction. The present invention can also be applied to the case of correcting only one of the misregistration and the misregistration. Even in the configuration in which only the positional deviation in the width direction is corrected, when the sheet is skewed, the timing at which the leading end of the sheet reaches the downstream side leading end detection sensor is different by performing positional deviation correction in the width direction. Therefore, the transport timing to the target value also fluctuates.

  Further, in the above embodiment, the sheet conveyance speed is adjusted by changing the conveyance rotation speed of the pinch roller pair 31, but the conveyance rotation speed of the pinch roller pair 31 is not changeable. Alternatively, a conveyance roller pair may be separately provided downstream of the nipping roller pair 31 to adjust the conveyance speed of the sheet.

  Further, in the above-described embodiment, although the case where the conveyance device according to the present invention is applied to an ink jet image forming apparatus is taken as an example, the conveyance device according to the present invention is also applicable to an electrophotographic image forming apparatus is there.

  FIG. 24 shows an example in which the conveyance device according to the present invention is applied to an electrophotographic image forming apparatus.

  In FIG. 24, 300 is an electrophotographic image forming apparatus, 302 is a document reading unit for optically reading image information of a document D, and 303 is a photosensitive drum with exposure light L based on the image information read by the document reading unit 302 An exposure unit for irradiating 305, a developing unit 304 for forming a toner image (image) on a photosensitive drum 305, and a transfer unit 307 for transferring a toner image formed on the photosensitive drum 305 onto a sheet P Forming unit) 310, a document conveying unit for conveying the set document D to the document reading unit 302, a sheet feeding unit (sheet feeding cassette) 312 to 314 containing the sheet P, 320 an unfixed sheet on the sheet P A fixing device for fixing an image, and a conveyance device 330 for conveying the sheet P fed from the paper feeding units 312 to 314 to the transfer unit 307.

  The basic operation of the electrophotographic image forming apparatus 300 will be briefly described.

  When the document D is conveyed by the document conveyance unit 310 in the direction of the arrow in FIG. 24 and the image information of the document D is read by the document reading unit 302, the exposure unit 303 to the charging surface on the photosensitive member 305 based on the image information. The exposure light L is emitted to form an electrostatic latent image on the photosensitive drum 305. Subsequently, toner is supplied from the developing unit 304 to the electrostatic latent image on the photosensitive member 305 to form a toner image (visible image). Further, the sheet P fed from any of the sheet feeding units 312 to 314 is conveyed by the conveyance device 330 to the transfer unit 307, and the toner image formed on the photosensitive member 305 is transferred onto the sheet P. Thereafter, the sheet P is conveyed to the fixing device 320, and after the toner image is fixed, the sheet P is discharged out of the apparatus.

  In such an electrophotographic image forming apparatus 300, it is necessary to adjust the transport speed of the sheet P so that the sheet P and the toner image on the photosensitive member 305 reach the transfer portion 307 at the same time. Therefore, by applying the same conveyance device as that of the above-described embodiment as the conveyance device 330 for conveying the sheet P to the transfer unit 307, it is possible to control the conveyance timing with high accuracy while correcting the positional deviation of the sheet P. P can be transported to the transfer unit 307.

  Further, the conveyance device according to the present invention is also applicable to a post-processing apparatus that performs staple processing, folding processing, and the like on a sheet after an image is transferred to the sheet.

  FIG. 25 shows an example in which the transfer device according to the present invention is applied to a post-processing device.

  The post-processing device 400 shown in FIG. 25 includes a punching device 410 for punching sheets, a staple processing device 420 for binding sheets, a folding device 430 for center-folding sheets, and a plurality of trays ( Stacking units) 441, 442, and 443 and a conveyance device 450 for conveying the sheet conveyed from the image forming apparatus 100 to the punching device 410. Further, the post-processing apparatus 400 conveys the sheet conveyed from the image forming apparatus 100 to any one of the three conveyance paths J1 to J3 and performs different post-processing.

  The first transport path J1 is a path for transporting a sheet punched by the punching device 410 or a sheet not punched to the first tray 441. The second conveyance path J2 is a path for conveying the sheet to the staple processing device 420 and conveying the sheet subjected to the binding processing to the second tray 442. The third conveyance path J3 is a path for conveying the sheet to the folding device 430 and conveying the center-folded sheet to the third tray 443.

  By applying the same conveyance device as that of the above-described embodiment as the conveyance device 450 provided in such a post-processing device 400, it is possible to accurately convey the sheet at a predetermined timing while correcting the positional deviation of the sheet. Therefore, it is possible to improve the accuracy of the subsequent punching processing, binding processing or center folding processing.

  Further, the transport device according to the present invention is not limited to the transport device that transports a sheet. The transport device according to the present invention includes paper (including plain paper, thick paper, thin paper, coated paper, label paper, envelopes, etc.), and other recording media on which an image such as an OHP sheet or OHP film is printed, or a document The present invention is also applicable to a conveyance device for conveying a sheet such as Furthermore, the transport apparatus according to the present invention is applicable not only to a sheet such as a recording medium or a document but also to a transport apparatus that transports a medium to be transported other than a sheet such as an electronic substrate.

7 Transfer device 11 Transfer cylinder (transfer rotating body)
16 Gripper (gripping part)
17 Rotary encoder (rotational speed detection means)
18 Laser Doppler Speedometer (Means for Detecting Transported Medium Speed)
23 Conveying speed control unit 31 Holding roller pair (position changing means)
57 Rotary encoder (drive position detection means)
58 Rotary encoder (drive position detection means)
101 First CIS (Position Detection Means)
102 Second CIS (Position Detection Means)
103 Third CIS (Position Detection Means)
P paper (medium to be transported)
Pa side end

JP 2005-53646 A

Claims (25)

Position detection means for detecting the position of the side end of the medium to be transported;
According to the position of the medium to be conveyed detected by the position detecting means, while conveying the medium to be conveyed, in at least one of the width direction of the medium to be conveyed and the rotation direction in the medium conveyance surface of the medium Position changing means for driving to change the position of the medium to be conveyed a plurality of times;
A transport device comprising
And a conveyance speed control unit configured to change the conveyance speed of the medium to be conveyed according to the position of the medium to be conveyed after the change by the position changing unit.   The conveyance apparatus according to claim 1, wherein the position detection unit can detect the position of the side end of the medium to be conveyed a plurality of times.   The conveyance apparatus according to claim 1, wherein the conveyance speed control unit changes the conveyance speed of the medium to be conveyed a plurality of times in accordance with the position of the medium to be conveyed after the change by the position changing unit.   The conveyance device according to claim 1, wherein the position changing unit is a roller pair that nips and conveys the medium to be conveyed. A plurality of position detection means capable of detecting the position of the side end of the medium to be transported;
According to the position of the medium to be conveyed detected by the position detecting means, while conveying the medium to be conveyed, in at least one of the width direction of the medium to be conveyed and the rotation direction in the medium conveyance surface of the medium Position changing means for driving to change the position of the medium to be conveyed;
A transport device comprising
And a conveyance speed control unit configured to change the conveyance speed of the medium to be conveyed according to the position of the medium to be conveyed after the change by the position changing unit.   The transport apparatus according to claim 5, wherein the position of the side end of the medium to be transported can be detected a plurality of times by the plurality of position detectors.   The conveyance apparatus according to claim 5, wherein the conveyance speed control unit changes the conveyance speed of the medium to be conveyed a plurality of times in accordance with the position of the medium to be conveyed after the change by the position changing unit.   The transport apparatus according to claim 5, wherein the plurality of position detection units are arranged on the upstream side and the downstream side in the transport direction of the medium to be transported with respect to the position change unit.   The conveying device according to claim 5, wherein the position changing unit is a roller pair which nips and conveys the medium to be conveyed. The apparatus further comprises drive position detection means for detecting a drive position when the position change means is driven in at least one of the width direction of the medium to be conveyed and the rotation direction in the medium conveyance surface of the medium.
The conveyance apparatus according to any one of claims 1 to 9, wherein the conveyance speed of the medium to be conveyed is changed based on the detection result of the drive position detection unit. A conveyance rotating body provided with an outer circumferential surface with a gripping portion for gripping the medium to be conveyed is disposed on the downstream side in the conveyance direction of the position changing means,
By changing the transfer speed of the transfer target medium based on the positional change amount of the transfer target medium, the transfer unit transfers the transfer target medium to the transfer rotating body in accordance with the timing at which the gripping unit grips the transfer target medium. The transport apparatus according to any one of claims 1 to 10. A rotational speed detection unit that detects the conveyance rotational speed of the conveyance rotary body;
The conveyance apparatus according to claim 11, wherein the conveyance speed of the medium to be conveyed is changed based on the positional change amount of the medium to be conveyed and the detection result of the rotational speed detection unit. And a medium speed detection unit for directly detecting the medium conveyance speed of the medium.
The transport apparatus according to any one of claims 1 to 12, wherein the transport speed of the transport medium is changed based on the positional change amount of the transport medium and the detection result of the transport medium speed detection unit. .   The number of times of position change of the medium to be conveyed by the position changing means and the number of times of change of the conveyance speed by the conveyance speed control unit are smaller than the number of times of position detection by the position detection means. The conveyance apparatus of 1 item.   An image forming apparatus comprising the conveyance device according to any one of claims 1 to 14. According to the position of the side edge of the medium to be detected, the medium to be conveyed is moved in at least one of the width direction and the rotation direction in the medium conveyance surface while conveying the medium to be conveyed. A transfer method for changing the position of the transfer medium a plurality of times,
The transport speed of the medium to be transported is adjusted according to the position after the change of the medium to be transported when the medium to be transported is moved in at least one of its width direction and the rotation direction in the medium transport surface. A transport method characterized by changing.   According to the position of the side end portion of the medium to be detected which is detected a plurality of times, at least one of the width direction of the medium to be conveyed and the rotation direction in the medium conveyance surface of the medium while conveying the medium to be transported. The transfer method according to claim 16, wherein the transfer is performed.   The transport speed of the medium to be transported is adjusted according to the position after the change of the medium to be transported when the medium to be transported is moved in at least one of its width direction and the rotation direction in the medium transport surface. The transfer device according to claim 16, wherein the change is made multiple times.   The position of the transferred medium is moved by moving the transferred medium in at least one of the width direction and the rotation direction in the transferred medium conveyance surface while holding the transferred medium by the roller pair and transferring it. The transfer method according to claim 16, wherein the change is made multiple times. Detecting a driving position of the roller pair when moving the medium to be conveyed in at least one of the width direction and the rotation direction in the medium conveyance surface of the medium;
20. The conveyance method according to claim 19, wherein the conveyance speed of the medium to be conveyed is changed based on the detected driving position of the roller pair. A conveying method for holding and conveying the medium to be conveyed conveyed by the pair of rollers by the grasping portion of a conveyance rotating body provided with a grasping portion on an outer peripheral surface thereof,
The transfer speed of the transfer medium is changed according to the position of the transfer medium after the change, so that the transfer medium is transferred to the transfer medium in accordance with the timing at which the gripping unit grips the transfer medium. The transfer method according to claim 19 or 20, wherein the transfer is performed.   22. The conveyance method according to claim 21, wherein the conveyance speed of the medium to be conveyed is changed based on the positional change amount of the medium to be conveyed and the conveyance rotational speed of the conveyance rotating body.   The conveyance speed of the said to-be-conveyed medium is changed based on the position change amount of the said to-be-conveyed medium, and the detection result which detected the conveyance speed of the said to-be-conveyed medium directly. Transport method.   The method according to any one of claims 16 to 23, wherein the number of times of changing the position of the medium to be conveyed and the number of times of changing the conveyance speed of the medium to be conveyed are smaller than the number of times the position of the side end of the medium to be conveyed is detected. The transport method according to any one of the above.   An image forming method comprising: conveying a medium to be conveyed by the conveyance method according to any one of claims 16 to 24; and forming an image on the medium to be conveyed.

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