JP2019156644A - Conveyance device, image formation device, conveyance method, and image formation method - Google Patents

Abstract

To receive a conveyed medium at a good timing.SOLUTION: A conveyance device comprises: position detection means 101-103 for detecting a position of a side end part Pa of a conveyed medium P; position changing means 31 for changing the position of the conveyed medium P by driving to at least one of a width direction of the conveyed medium and a rotation direction in the conveyed medium conveying surface while conveying the conveyed medium P corresponding to the detected position of the conveyed medium P by the position detection means 101-103; and a conveyance rotating body 8 which is arranged at the downstream side in the conveyance direction of the position changing means 31 and is provided with a receiving part for receiving the conveyed medium P. Further, a rotational speed control part for changing the rotational speed of the conveyance rotating body 8 corresponding to the position after changing of the conveyed medium P by the position changing means 31 is provided.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a transport device that transports a transported medium, an image forming apparatus including the transport device, a transport method that transports a transported medium, and an image forming method using the transport method.

  As a transport device that transports a transported medium, for example, a transport device that transports a sheet such as a sheet or a document in an image forming apparatus such as a copying machine or a printer is known.

  Conventionally, in this type of conveying apparatus, when conveying a sheet to an image forming unit, an image transfer unit, or the like, the conveyed sheet is abutted against the nip of a conveying roller pair that is stopped 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 brought into contact with the nip of the conveying roller pair temporarily stops the sheet, so that there is a problem that productivity (image forming speed) is reduced.

  In order to solve such a problem, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2005-53646), a conveyance roller is conveyed while conveying a sheet in order to correct a positional deviation such as skew of the sheet without reducing productivity. A conveyance device has been proposed that corrects misalignment without stopping the sheet by driving the pair in a direction opposite to the misalignment direction of the sheet.

  Specifically, in the conveyance device described in Patent Document 1, as shown in FIG. 23, 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 alternate long and short dash line O). The leading edge 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. 24, the positional deviation (skew) of the sheet 900 is corrected by tilting the conveyance roller pair (registration roller pair) 800 according to the calculated skew feed amount θ.

  By the way, when the positional deviation of the sheet is corrected while the sheet is conveyed as described above, the leading edge position of the sheet changes, and therefore the time until the leading edge of the sheet reaches a predetermined target position changes. Accordingly, when the sheet is conveyed at a preset conveyance speed, the timing at which the sheet reaches the target position is shifted, and there is a problem that the sheet cannot be conveyed with high accuracy.

  Therefore, in the conveyance device described in Patent Document 1, in order to eliminate the deviation of the sheet arrival timing associated with the correction of the positional deviation of the sheet, the sheet leading edge position after the positional deviation correction is calculated from the amount of positional deviation of the sheet, and the calculation The sheet conveyance speed is adjusted based on the result.

  However, if the conveyance speed (rotational speed) of the conveyance roller pair is controlled while conveying the sheet as in the conveyance device described in Patent Document 1, slipping may occur between the conveyance roller pair and the sheet. . When such a slip occurs, the arrival timing of the sheet at the target position is shifted, and the sheet cannot be conveyed with high accuracy.

  In order to solve the above-described problems, the present invention provides a position detection unit that detects a position of a side end portion of a transported medium, and the transported medium according to a position of the transported medium detected by the position detection unit. Position changing means for changing the position of the transported medium by driving in at least one of the width direction of the transported medium and the rotational direction in the transported medium transport surface A transport rotator disposed downstream in the transport direction and provided with a receiving unit that receives the transported medium, according to the position after the change of the transported medium by the position changing unit And a rotation speed control unit that changes the rotation speed of the transport rotator.

  According to the present invention, even if the transport timing of the transported medium changes with the change in the position of the transported medium by the position changing means, the rotational speed of the transport rotator according to the changed position of the transported medium. By changing, the receiving unit can reach a desired position in accordance with the transport timing of the transported medium. As a result, the receiving medium can be received with high accuracy (with good timing) by the receiving unit.

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 conveying apparatus concerning this embodiment. It is a side view of the drive mechanism which drives a pinching roller pair. It is a top view of the drive mechanism which drives a pinching roller pair. (A) is a diagram showing a state in which the holding frame is moved only in the width direction, (b) is a diagram showing a state in which the holding frame is moved only in the rotation direction within the paper conveyance surface, and (c) is a diagram showing the state in which the holding frame is in the width direction FIG. 6 is a diagram illustrating a state of moving in both directions of the rotation direction in the sheet conveyance surface. It is a block diagram which shows the control system of the conveying apparatus which concerns on this embodiment. It is a figure which shows the method of calculating the amount of position shift from the positional information on the sheet | seat obtained using two CIS. It is a figure for demonstrating the amount of position shift of the width direction. It is a figure which shows a motion of the conveying 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 conveying 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 conveying 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 conveying 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 conveying 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 conveying 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 a conveyance operation | movement. It is a figure which shows the flowchart of rotation speed control. FIG. 6 is a diagram for explaining a calculation method of a positional change amount of a sheet accompanying positional deviation correction. FIG. 6 is a diagram illustrating an example in which an upstream transfer cylinder, a sheet carrying drum, and a downstream transfer cylinder are interlocked and connected. 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 conveyance operation which concerns on other 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 conveyance operation which concerns on another embodiment. It is a top view of the conventional conveying apparatus. It is a top view of the conventional conveying apparatus.

  Hereinafter, the present invention will be described with reference to the accompanying drawings. In the drawings for explaining the present invention, components such as members and components having the same function or shape are denoted by the same reference numerals as much as possible, and once described, the description will be given. Omitted.

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

[overall structure]
An ink jet image forming apparatus 100 according to the present embodiment mainly includes a paper feeding unit 1, an image forming unit 2, a drying unit 3, and a paper discharge unit 4. In the ink jet image forming apparatus 100, an image is formed on the paper P as a sheet supplied from the paper supply unit 1 by ink that is an image forming liquid in the image forming unit 2. Then, after the ink attached on the paper P is dried in the drying unit 3, the paper P is discharged from the paper discharge unit 4. In the case of duplex printing, after an image is formed on the front side of the paper P in the image forming unit 2, the drying unit 3 performs a drying process, and the paper P is transported to the reverse transport path 150 without being discharged. To do. The paper P passes through the reverse conveyance path 150 and is supplied to the image forming unit 2 again in a state where the paper is reversed, and after the image is formed on the back side of the paper P in the image forming unit 2, the drying unit 3 is dried and discharged from the paper 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 and feeds the sheets P from the sheet feeding tray 5 one by one, and a feeding device 6 And a conveying device 7 that conveys the sheet P. As the feeding device 6, any feeding device such as a device using a roller or a roller or a device using air suction can be used. The paper P sent out from the paper feed tray 5 by the feeding device 6 is conveyed to the image forming unit 2 by the conveying device 7.

[Image forming unit]
The image forming unit 2 mainly receives the fed paper P and transfers it to the paper carrying drum 9 as a first transport rotating body 8 and the paper P transported by the transfer cylinder 8 on the outer peripheral surface. A paper carrying drum 9 as a second carrying rotating body carried and carried, an ink discharge unit 10 that ejects ink toward the paper P carried on the paper carrying drum 9, and the paper carrying drum 9 carried the paper. A transfer cylinder 11 serving as a third transport rotating body that transfers the paper P to the drying unit 3 is configured. The upstream transfer cylinder 8, the paper carrying drum 9, and the downstream transfer cylinder 11 also serve as a part of the transport device 7 that transports the paper P.

  The leading edge of the sheet P conveyed from the sheet feeding unit 1 to the image forming unit 2 is gripped by a swingable gripper 16 as a receiving unit provided on the surface of the transfer cylinder 8, and the surface of the transfer cylinder 8 is moved. It is transported with it. The paper P conveyed by the transfer cylinder 8 is delivered to the paper carrying drum 9 at a position facing the paper carrying drum 9. In the example shown in FIG. 1, only one gripper 16 is described, but a plurality of grippers 16 may be provided on the transfer cylinder 8.

  A similar gripper is provided on the surface of the paper carrying drum 9 as a receiving portion, and the leading edge of the paper is gripped by the gripper. In addition, a plurality of suction holes are dispersedly formed on the surface of the paper carrying drum 9, and a suction air flow toward the inside of the paper carrying drum 9 is generated by the suction device 12 in each suction hole. The front end of the paper P transferred from the transfer cylinder 8 to the paper carrying drum 9 is gripped by the gripper, and is attracted to the surface of the paper carrying drum 9 by the suction airflow, and accompanying the surface movement of the paper carrying drum 9 Be transported.

  The ink discharge unit 10 according to the present embodiment forms an image by discharging four color inks of C (cyan), M (magenta), Y (yellow), and K (black). Individual liquid discharge heads 10C, 10M, 10Y, and 10K are provided. The liquid ejection heads 10C, 10M, 10Y, and 10K are not limited in configuration as long as they eject liquid, and any configuration can be adopted. If necessary, a liquid discharge head that discharges special inks such as white, gold, and silver may be provided, or a liquid discharge head that discharges liquid that does not constitute an image, such as a surface coating liquid, may be provided.

  The discharge operations of the liquid discharge heads 10C, 10M, 10Y, and 10K of the ink discharge unit 10 are controlled by drive signals corresponding to image information. When the paper P carried on the paper carrying drum 9 passes through the region facing the ink ejection unit 10, each color ink 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, the configuration of the image forming unit 2 is not limited as long as the image is formed by adhering liquid onto the paper P.

[Dry section]
The drying unit 3 mainly includes a drying mechanism 13 for drying the ink adhered on the paper P in the image forming unit 2 and a transport mechanism 14 for transporting the paper P transported from the image forming unit 2. Has been. The paper P transported from the image forming unit 2 is received by the transport mechanism 14, transported to pass through the drying mechanism 13, and delivered to the paper discharge unit 4. When passing through the drying mechanism 13, the ink on the paper P is subjected to a drying process, whereby liquid components such as moisture in the ink are evaporated, and the ink is fixed on the paper P and the paper P is curled. It is suppressed.

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

[Other additional functions]
The ink jet image forming apparatus 100 according to this embodiment includes a paper feeding unit 1, an image forming unit 2, a drying unit 3, and a paper discharge unit 4. However, other functional units may be added as appropriate. For example, after a pre-processing unit that performs pre-processing of image formation is added between the paper feeding unit 1 and the image forming unit 2 or after post-processing of image formation is performed between the drying unit 3 and the paper discharge unit 4 A processing unit can be added.

  Examples of the pre-processing unit include a unit that performs a processing liquid application process that applies a processing liquid that reacts with ink and suppresses bleeding to the paper P. However, the content of the pre-processing is not particularly limited. . Further, as the post-processing unit, for example, a sheet reversal conveyance process for inverting the sheet P on which the image is formed in the image forming unit 2 and sending the sheet P to the image forming unit 2 again to form images on both sides of the sheet P. A process for binding a plurality of sheets of paper P on which an image has been formed may be mentioned, but there is no particular limitation on the content of post-processing.

  Note that the “image” formed on the paper is not limited to a visual image of a significant image such as a character or graphic, and includes, for example, a pattern that does not have any meaning. In addition, the “sheet” on which the image is formed is not limited to a material, and liquid such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics can be attached even temporarily. Any material may be used, for example, a film product, a cloth product for clothing, a building material such as wallpaper or flooring, or a leather product. The “liquid” is not particularly limited as long as it has a viscosity and surface tension that can be ejected from the head, and the viscosity becomes 30 mPa · s or less at room temperature, normal pressure, or by heating and cooling. Preferably there is. More specifically, solvents such as water and organic solvents, colorants such as dyes and pigments, functional materials such as polymerizable compounds, resins, and surfactants, and biocompatible materials such as DNA, amino acids, proteins, and calcium. , Edible materials such as natural pigments, and the like, suspensions, emulsions, and the like, which can be used in applications such as ink jet inks and surface treatment liquids.

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

  The “liquid ejection head” is a functional component that ejects and ejects liquid from ejection holes (nozzles). As an energy generation source for discharging liquid, piezoelectric actuators (laminated piezoelectric elements and thin film piezoelectric elements), thermal actuators using electrothermal transducers such as heating resistors, electrostatic actuators composed of diaphragms and counter electrodes, etc. Although energy generation means can be used, the discharge energy generation means to be used is not limited.

  Next, the conveying device 7 provided in the paper feeding unit 1 according to this embodiment will be described.

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

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

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

  Each of the tip detection sensors 200 and 220 is configured by a reflective optical sensor or the like. The upstream end detection sensor 220 is disposed upstream of the sandwiching roller pair 31 and downstream of the second CIS 102. The downstream-side tip detection sensor 200 is disposed downstream of the sandwiching roller pair 31 and upstream of the third CIS 103. When the paper P is transported, the leading edge Pb of the paper P is detected by the upstream leading edge detection sensor 220, so that the transport timing at which the leading edge Pb of the paper P reaches the upstream leading edge detection sensor 220 is detected. The Further, after the sheet P is nipped by the pair of nipping rollers 31, when the leading end portion Pb of the sheet P reaches the position of the downstream end detecting sensor 200, the leading end portion Pb of the sheet P is detected by the downstream end detecting sensor 200. Then, the conveyance timing at which the leading edge Pb of the paper P reaches the downstream leading edge detection sensor 200 is detected.

  The nipping roller pair 31 moves in the width direction of the sheet P (in the direction of arrow S in FIG. 2) while nipping the sheet P being conveyed, or within the sheet conveying surface about the support shaft 73 (in FIG. 2). The position of the paper P is changed. As a result, the positional deviation α in the width direction of the paper P and the skew positional deviation β are corrected. In other words, the sandwiching roller pair 31 functions as a misalignment correction unit that corrects misalignment of the paper P. In the present embodiment, the support shaft 73 is provided on one end side in the axial direction of the sandwiching roller pair 31, but the support shaft 73 may be provided at the axial center position of the sandwiching roller pair 31.

  Further, the transfer cylinder 8 which is a component of the transfer device 7 includes a transfer cylinder drive motor 81 as a transfer rotating body driving unit that rotates the transfer cylinder 8, and a rotation speed detection unit that detects the rotation speed of the transfer cylinder 8. The rotary encoder 82 is provided. The rotation speed of the transfer drum 8 is controlled based on the detection result of the rotary encoder 82.

  3 and 4 show the configuration of a drive mechanism that drives the pair of clamping rollers. 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 includes a driving roller 31a that is driven to rotate about a roller axis, and a driven roller 31b that is driven to rotate together with the driving roller 31a. These sandwiching roller pairs 31 are held rotatably around a 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 main 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 support member. Accordingly, the holding frame 72 is configured to be movable in any direction within the sheet conveyance surface (within the conveyance medium conveyance surface) along the upper surface of the base frame 71. Thus, by supporting the holding frame 72 using the free bearing 95, the frictional load when the holding frame 72 moves can be extremely reduced. For this reason, it is possible to carry out correction of sheet misalignment, which will be described later, at high speed and with high accuracy. In this embodiment, the holding frame 72 is supported by four free bearings 95, but the number of free bearings 95 may be three or more.

  Further, as shown in FIG. 3, the holding frame 72 is provided with the support shaft 73 serving as a center of rotation of the sandwiching roller pair 31 within the sheet conveying surface extending downward. A lower end portion of the support shaft 73 is inserted into a width direction guide portion 71 a formed on the base frame 71. The width direction guide portion 71a is a hole formed so as to extend substantially linearly in the width direction (the direction of arrow S in FIG. 4). In addition, a guide roller 79 is rotatably provided at the lower end portion of the support shaft 73, and the support shaft 73 is inserted through the guide roller 79 so as to contact 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 pair of clamping rollers 31 held by the holding frame 72 also move in the width direction. The holding frame 72 is also configured to rotate about the support shaft 73 within the sheet conveyance surface (in the direction of arrow W in FIG. 4). As the holding frame 72 rotates around the support shaft 73, the pair of nipping rollers 31 rotates within the sheet conveying surface.

  As shown in FIG. 3, the bracket 69 provided on the right end side of the main body frame 70 in the drawing has a conveyance drive motor (conveyance drive means) 61 that applies a driving force for paper conveyance to the pair of clamping rollers 31. Is provided. The conveyance drive motor 61 and the drive roller 31a of the pair of clamping rollers 31 are connected via a gear train including a plurality of gears 66 and 67 and a coupling mechanism 65. The coupling mechanism 65 maintains the connection so that the driving force can be transmitted even if the rotating shaft of the driving roller 31a and the rotating shaft of the gear 67 are separated or approach each other in the axial direction or are driven in the directions inclined with respect to each other. This is a two-stage spline coupling. In this way, the drive roller 31a and the gear 67 are connected via the coupling mechanism 65, so that the pair of nipping rollers 31 moves in the width direction or rotates in the sheet conveyance surface, and the drive roller 31a. Even if the relative position between the transport drive motor 61 and the transport drive motor 61 changes, it is possible to satisfactorily transmit the drive force from the transport drive motor 61 to the drive roller 31a.

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

  In addition, the transport device 7 according to the present embodiment includes a width direction driving mechanism 38 that moves the holding frame 72 and the sandwiching roller pair 31 in the sheet width direction, and a rotation of the retaining frame 72 and the sandwiching roller pair 31 in the sheet transport surface. And a skew direction driving mechanism 39 that rotates in the direction.

  As shown in FIGS. 3 and 4, the width direction drive mechanism 38 includes 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 direction in the 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 shaft 45a. In addition, the cam 45 is held in a state where it is in contact with a cam follower 46 provided on the support shaft 73 by the urging force of the tension spring 59. When the cam 45 rotates, the cam follower 46 is pushed against the urging force of the tension spring 59, so that the holding frame 72 moves in the width direction (right direction in FIG. 4).

  Further, as shown in FIG. 3, a timing belt 97 is stretched between the rotation shaft 45 a of the cam 45 and the motor shaft of the width direction drive motor 62. As a result, the driving force is transmitted from the width direction driving motor 62 to the cam 45 via the timing belt 97. A rotary encoder 57 as a rotation angle detecting means for detecting the rotation angle (rotation amount) of the cam 45 is provided on the rotation shaft 45 a of the cam 45. 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 a drive position when the holding frame 72 and the sandwiching roller pair 31 move in the width direction.

  As shown in FIGS. 3 and 4, the skew direction drive mechanism 39 includes a skew direction drive motor (skew 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 shaft 47a. The cam 47 is held in contact with a cam follower 48 provided at one end of the lever member 50 by the urging force of the tension spring 60. In addition, an action roller 49 is rotatably provided at the opposite end of the lever member 50. The action roller 49 is held in a state of being in contact with the protrusion 72 a provided on the holding frame 72 by the urging force of the tension spring 60. With this configuration, when the cam 47 rotates and the cam follower 48 is pushed 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, so that the holding frame 72 is rotated in the rotation direction within the sheet conveying surface. Rotate (counterclockwise in FIG. 4).

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

  FIG. 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. FIG. 5B shows a skew direction drive mechanism. In this state, only the 39 cam 47 is rotated, and the holding frame 72 is rotated in the sheet conveying surface. FIG. 5C shows a state in which both the cams 45 and 47 are rotated, the holding frame 72 is moved in the width direction, and is rotated in the sheet conveying surface.

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

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

  The transport apparatus according to the present embodiment includes a control unit 20 that controls the operations of the clamping roller pair 31 and the transfer cylinder 8 disposed on the downstream side in the transport direction. The control unit 20 controls the positional deviation correction operation of the pair of clamping rollers 31, that is, the amount of movement in the width direction of the pair of clamping rollers 31, the amount of rotation in the sheet conveyance surface, and the rotation speed of the transfer cylinder 8.

  As shown in FIG. 6, the control unit 20 includes a misregistration amount calculation unit 21 that calculates the misregistration amount of the paper, a target reception timing calculation unit 24 that calculates a target reception timing at which the transfer cylinder 8 receives the paper, and a transfer. And a rotation speed control unit 25 that controls the conveyance rotation speed of the barrel 8.

  The misregistration amount calculation unit 21 is configured to calculate the misregistration amount of the paper based on the detection results of the CISs 101 to 103. Based on the positional deviation amount of the paper calculated by the positional deviation amount calculation unit 21, the control unit 20 controls the nipping roller pair 31. That is, the control unit 20 performs the width direction driving motor 62 that drives the pair of sandwiching rollers in the width direction and the skew that rotates the pair of sandwiching rollers in the rotation direction within the sheet transport surface in order to correct the positional deviation of the sheet. Each of the row direction drive motors 63 is controlled.

  The target reception timing calculation unit 24 detects the conveyance position information of the paper detected by the downstream end detection sensor 200 and the rotation of the transfer cylinder 8 detected by the home position sensor 80 (see FIG. 1) provided on the transfer cylinder 8. Based on the position information, a target reception timing at which the transfer cylinder 8 receives the paper is calculated. As described above, in the present embodiment, the transfer of the paper P to the transfer cylinder 8 is performed by gripping the paper P by the gripper 16 provided on the transfer cylinder 8. At this time, in order to surely deliver the paper P to the gripper 16, the gripper 16 similarly matches the timing at which the paper P reaches the paper receiving position A of the gripper 16 (see FIG. 1). Is required to reach Therefore, in this embodiment, the timing at which the paper P reaches the paper receiving position A is set as the target receiving timing. The timing at which the gripper 16 reaches the paper gripping position A is specified by detecting the rotation reference position C of the transfer cylinder 8 by the home position sensor 80.

  The rotation speed control unit 25 rotates the transfer cylinder 8 based on the detection information of the rotary encoder 82 (see FIG. 2) that detects the rotation speed of the transfer cylinder 8 and the positional change amount of the paper that has been changed by the misalignment correction. Control the speed. Here, the amount of change in the position of the sheet at the time of misalignment correction is the amount of movement that the nipping roller pair 31 moves in the width direction when the misalignment correction of the sheet is performed and the amount of rotation that rotates in the rotation direction within the sheet transport surface. Equivalent to. Therefore, in the present embodiment, the rotation speed control unit 25 receives the detection signals of the rotary encoders 57 and 58 that detect the amount of movement of the clamping roller pair 31 in the width direction and the amount of rotation in the sheet conveyance surface. The position change amount of is indirectly acquired.

  The rotation speed control unit 25 controls the rotation speed of the transfer cylinder 8 based on the target reception timing calculated by the target reception timing calculation unit 24 or the corrected target reception timing thereafter.

  Next, a method for calculating the amount of paper misregistration will be described with reference to FIGS. Note that FIG. 7 shows a method of calculating the amount of paper misregistration using the first CIS 101 and the second CIS 102, but the paper position using the second CIS 101 and the third CIS 103 is shown. The calculation method of the deviation amount is the same.

  As shown in FIG. 7, when the leading end portion Pb of the paper P passes through the first CIS 101 and reaches the second CIS 102, the positional deviation amount α in the width direction of the paper P and the positional deviation amount β of the skew are obtained. Detected.

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

  Also, the skew positional deviation β is calculated from the difference in the edge position in the width direction of the paper P detected by each of the first CIS 101 and the second CIS 102. That is, as shown in FIG. 7, when the leading edge Pb of the paper P reaches the second CIS 102, the distances K1, K2 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 preset distance M1 between the first CIS 101 and the second CIS 102, skew is performed using the equation tan β = (K1−K2) / M1. Is calculated.

  In this way, the positional displacement amount α in the width direction and the skewed positional displacement amount β are calculated. As shown in FIG. 8, by performing the skew displacement correction, when the sheet moves from the position P to the position P ′, the displacement amount in the width direction changes from α to α ′. Therefore, by calculating in advance the positional deviation amount α ′ in the width direction, it is possible to perform more accurate positional deviation correction. However, the positional deviation amount α ′ in the width direction varies depending on which position is used as a reference for correcting the positional deviation in the skew.

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

  As shown in FIGS. 9A and 9B, when the paper P has been transported, the pair of nipping rollers 31 is disposed at a home position where the roller shaft is orthogonal to the transport direction (left-right direction in the figure). ing. In this state, the pair of clamping rollers 31 are separated from each other and stand by in a stationary state.

  Thereafter, as shown in FIGS. 10A and 10B, when the leading end portion Pb of the sheet P passes through the first CIS 101 and reaches the second CIS 102, the sheet is formed by the first CIS 101 and the second CIS 102. “First position detection” is performed in which the position of the side edge portion Pa of P is detected (S1 in FIG. 15). Then, based on the position information detected by these CISs 101 and 102, the positional deviation amount α in the width direction (or the positional deviation amount α ′ including the deviation amount associated with the positional deviation correction of the skew feeding) and the position of the skew feeding. The displacement amount β is calculated by the positional displacement amount calculation unit 21 (see FIG. 6). Based on the calculated displacement amount, the width direction drive motor 62 and the skew direction drive motor 63 are controlled to move the pair of clamping rollers 31 in the width direction (in the direction of arrow S1 in FIG. 10). It is rotated in the direction of rotation within the sheet conveying surface (in the direction of arrow W1 in FIG. 10). As a result, a pick-up operation is performed in which the nipping roller pair 31 faces the front end portion Pb of the paper P (S2 in FIG. 15).

  Thereafter, when the leading edge portion Pb of the paper P is detected by the upstream-side leading edge detection sensor 220 and the nipping roller pair 31 comes into contact with each other based on the detection timing and the conveyance rotation is started, it is shown in FIGS. As described above, the sheet P is received by the pair of nipping rollers 31 facing each other, and the sheet P is conveyed while being nipped by the pair of nipping rollers 31. Note that when the paper P is delivered to the sandwiching roller pair 31, the transport roller pair 44 on the upstream side of the sandwiching roller pair 31 is separated from each other.

  Further, as shown in FIGS. 11A and 11B, when the paper P is conveyed by the sandwiching roller pair 31 and the leading end portion Pb of the paper P reaches the position of the downstream leading edge detection sensor 200, the downstream leading edge detection sensor. 200 detects the leading edge Pb of the paper P (S3 in FIG. 15). As a result, the timing at which the leading edge Pb of the paper P reaches the downstream leading edge detection sensor 200 is detected. Based on the detection information of the downstream end detection sensor 200 and the detection information of the home position sensor 80 of the transfer cylinder 8, the target reception timing of the sheet to the sheet reception position A of the transfer cylinder 8 is the target reception timing calculation unit. 24 (see FIG. 6) and set (S4 in FIG. 15).

  Thereafter, as shown in FIGS. 12A and 12B, while the paper P is being conveyed by the pair of sandwiching rollers 31, the direction in which the pair of sandwiching rollers 31 is picked up is opposite to the above-described pick-up operation (the direction of arrow S2 and the direction of arrow W2) A return operation is performed to drive (step S5 in FIG. 15). As a result, the “first correction” is performed in which the positional deviation in the width direction of the paper P and the skewed positional deviation are corrected. In the flowchart shown in FIG. 15, the return operation (first correction) S5 is displayed in the order after the detection S3 of the downstream side tip detection sensor 200, but the return operation S5 is downstream immediately after the welcome operation S2. It may be started before the detection S3 of the side tip detection sensor 200.

  Further, as shown in FIGS. 13A and 13B, when the leading end Pb of the paper P reaches the third CIS 103, the second CIS 102 and the third CIS 103 again cause the side edge Pa of the paper P to be “Second position detection” in which the position is detected is performed (S6 in FIG. 15). Then, based on the position information detected by the CISs 102 and 103, the positional deviation amount in the width direction and the skew positional deviation amount are calculated by the positional deviation amount calculation unit 21. Then, the width direction drive motor 62 and the skew direction drive motor 63 are controlled based on the calculated displacement amount, and the clamping roller pair 31 is moved in the width direction (in the direction of arrow S3 or arrow S4 in FIG. 13). In addition to the movement, the “second correction” for correcting the positional deviation of the paper P is performed by rotating in the rotational direction in the paper conveyance surface (in the direction of arrow W3 or arrow W4 in FIG. 13) (FIG. 15). S7).

  Thus, even after the returning operation (first correction), the positional deviation of the paper P is detected (second positional detection), and the positional deviation of the paper P is corrected based on the detection result (second correction). ), The misalignment that occurs while the paper P is being conveyed by the pair of clamping rollers 31 can be eliminated. In addition, such misalignment detection (second position detection) after the returning operation can be performed a plurality of times at a predetermined interval as long as the sheet passes through the second CIS 102 and the third CIS 103. Therefore, by performing such misregistration detection (second position detection) a plurality of times and performing misregistration correction (second correction) each time, it becomes possible to convey the paper with higher accuracy.

  However, if the above-described misalignment correction is performed after the target reception timing is set, the position of the paper in the transport direction changes accordingly, so if the paper is transported at the same transport speed, the paper is received. The timing for reaching position A changes. As a result, the timing at which the paper reaches the paper receiving position A and the timing at which the gripper 16 of the transfer cylinder 8 reaches the paper receiving position A are shifted, and the gripper 16 may not be able to grip the paper with high accuracy. To solve such a problem, a method of adjusting the conveyance speed of the paper in accordance with the timing when the gripper 16 reaches the paper receiving position A by changing the conveyance rotation speed of the pair of nipping rollers 31 that convey the paper is considered. It is done. However, in this method, when the conveyance rotation speed of the pair of nipping rollers 31 is changed, there is a possibility that slip occurs between the pair of nipping rollers 31 and the sheet, and the sheet conveyance timing cannot be corrected with high accuracy. There is.

  Therefore, in this embodiment, when the misalignment correction (second correction) is performed after the target reception timing is set (every misalignment correction is performed), the receiving side is based on the misalignment correction amount of the sheet. The rotational speed of the transfer cylinder 8 is changed (corrected) (S8 in FIG. 15). On the other hand, the clamping roller pair 31 is controlled to rotate at a predetermined (constant) conveyance rotation speed set in advance based on detection information of a rotary encoder 96 (see FIG. 3) provided in the clamping roller pair 31. Has been.

  As described above, when the rotation speed of the transfer cylinder 8 is changed based on the paper misalignment correction amount, the timing at which the paper P reaches the paper receiving position A as shown in FIGS. Accordingly, the gripper 16 of the transfer cylinder 8 reaches the paper receiving position A (S9 in FIG. 15), and the paper P can be reliably received (gripped) by the gripper 16. When the paper P reaches the paper receiving position A, the nipping roller pair 31 is separated from each other, and the conveyance of the paper by the nipping roller pair 31 is completed. If the misalignment correction is not performed after the target receiving timing is set, the arrival timing of the sheet at the sheet receiving position A basically does not change, so the rotational speed of the transfer cylinder 8 corresponding to the misalignment correction is not changed. No change is made.

  Hereinafter, a method for controlling the rotational speed of the transfer drum 8 will be described with reference to the flowchart of FIG.

  As shown in FIG. 16, when the control of the rotational speed of the transfer cylinder 8 is started, the gripper 16 is first set based on the detection information of the home position sensor 80 of the transfer cylinder 8 before the target reception timing is set. Is at the rotation reference position C (S11 in FIG. 16). As described above, the leading edge of the sheet is detected by the downstream leading edge detection sensor 200 (S12 in FIG. 16), and the target reception timing is determined based on the detection information and the detection information of the home position sensor 80 of the transfer cylinder 8. It is set (S13 in FIG. 16).

  The target rotational speed of the transfer cylinder 8 is calculated in accordance with the set target reception timing (S14 in FIG. 16). The calculation of the target rotation speed of the transfer cylinder 8 may be performed by the target reception timing calculation unit 24 or may be performed by another calculation unit. Then, the rotational speed of the transfer cylinder 8 is controlled based on the calculated target rotational speed (S15 in FIG. 16). In the present embodiment, the rotational speed of the transfer cylinder 8 is managed based on a signal from a rotary encoder 82 provided on the transfer cylinder 8. Accordingly, in order to determine whether the rotation speed of the transfer cylinder 8 is faster or slower than the target rotation speed, the rotation speed control unit 25 acquires a signal from the rotary encoder 82 (S16 in FIG. 16).

  In addition, when the misalignment correction is performed by the pair of clamping rollers 31 after the target reception timing is set, the rotation speed of the transfer cylinder 8 is changed based on the misalignment correction amount of the sheet accompanying the misalignment correction. This misregistration correction amount corresponds to a driving position (driving amount and driving direction) in which the clamping roller pair 31 is driven in the width direction or the rotation direction in the sheet conveyance surface during the misalignment correction. Therefore, in the present embodiment, the rotational speed control unit 25 acquires signals from the rotary encoders 57 and 58 that detect the width direction of the pinching roller pair 31 and the driving amount and driving direction in the sheet conveyance surface (see FIG. 16). S17). Then, the target rotational speed of the transfer cylinder 8 is calculated based on the target reception timing and the signals from the rotary encoders 82, 57, and 58 (S14 in FIG. 16). Then, the rotation speed of the transfer cylinder 8 is controlled based on the newly calculated target rotation speed (S15 in FIG. 16). Then, the rotation speed of the transfer cylinder 8 is controlled until the sheet conveyance time reaches the target reception timing (S18 in FIG. 16). When the paper transport time reaches the target reception timing, the gripper 16 reaches the paper reception position A in synchronization with the paper (S19 in FIG. 16). As a result, the gripper 16 can reliably hold the paper in a timely manner.

  Hereinafter, a method for calculating the amount of change in the position of a sheet accompanying correction of misalignment will be described using FIG.

  In FIG. 17, the point Z is the position of the rotation center (support shaft 73) in the sheet conveyance surface when the pair of nipping rollers 31 is disposed at the home position, the point R is the measurement reference point, and the point Q is The position Q ′ of the leading edge of the sheet when the time t has elapsed since the downstream leading edge detection sensor 200 detected the leading edge of the sheet, the position Q ′ is corrected at the timing immediately before the time t (time t−1). Indicates the position of the leading edge of the paper when In FIG. 17, the characters in parentheses indicate points Z, Q, and Q with reference to the measurement reference point R when the paper transport direction is the X direction and the direction orthogonal to the paper transport direction is the Y direction. The X and Y coordinates of Q ′. In addition, θ is an inclination angle (rotation angle within the sheet conveyance surface) of the pair of nipping rollers 31 when the sheet leading edge reaches the position of point Q, and θ ′ is a point Q at the sheet leading edge. This is an inclination angle (rotation angle in the sheet conveyance surface) of the pair of clamping rollers 31 from the home position when the position 'is reached. Δθ is a difference between the inclination angles θ and θ ′.

  As described above, when the position of the leading edge of the paper P changes with the misalignment correction operation, the position coordinates (Qx, Qy) of the paper leading edge position Q at time t use the following formulas 1 and 2. Can be calculated.

Qx = cos (Δθ) (Qx′−Zx) −sin (Δθ) (Qy′−Zy)
+ Zx + Xp Equation 1
Qy = sin (Δθ) (Qx′−Zx) + cos (Δθ) (Qy′−Zy)
+ Zy + Yp + Ys Equation 2

  Xp in the above formula 1 is a component in the X direction of the transport distance in which the paper P is transported until the timing one time before the time t (time t−1), and Yp in the above formula 2 is This is the Y direction component of the transport distance. If the transport distance (transport distance in the direction orthogonal to the roller axis) by which the paper P is transported by the sandwiching roller pair 31 during time t−1 is Fp, Xp and Yp are expressed by the following formulas 3 and 4. be able to. Ys in Equation 2 is the movement amount in the width direction (Y direction movement amount) of the paper P from the point Q ′ to the point Q.

Xp = cos (θ ′) Fp Equation 3
Yp = sin (θ ′) Fp Equation 4

  Therefore, the position coordinates (Qx, Qy) of the paper leading edge position Q at time t can be calculated by using the above formulas 1 to 4.

  Then, by subtracting the X coordinate Vx of the paper leading edge position 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 edge of the paper accompanying the positional deviation correction. Is calculated (see Equation 5 below). Based on the position change amount G calculated in this way, a time (target reception timing) until the paper reaches the paper reception position A is calculated, and the rotation speed of the transfer cylinder 8 is calculated based on the calculated time. By adjusting, the sheet can be transferred to the transfer cylinder 8 (gripper 16) at a predetermined timing.

  G = Qx−Vx Equation 5

  As described above, according to the transport device according to the present embodiment, even if the position in the transport direction of the paper changes due to the positional deviation correction, the positional deviation correction amount (width) The gripper is adjusted in accordance with the timing at which the paper reaches the paper receiving position A by changing (correcting) the rotational speed of the transfer cylinder 8 based on the direction and the rotational position of the paper in the rotational direction within the paper conveyance surface. 16 can reach the paper receiving position A. Further, by correcting the rotational speed of the receiving transfer cylinder 8 instead of the conveying speed of the paper-feeding clamping roller pair 31, the occurrence of slippage between the clamping roller pair 31 and the paper can be avoided, The paper can be delivered to the transfer cylinder 8 with high accuracy. As a result, it is possible to prevent the positional deviation of the image with respect to the sheet with high accuracy, and the print quality is improved. In addition, when performing double-sided printing, it is possible to correct the positional deviation of the image with respect to the front side surface and the back side surface, so it is possible to eliminate the relative positional deviation between the front side image and the back side image. .

  In this embodiment, every time the position of the paper is detected, the positional deviation is corrected and the rotation speed of the transfer cylinder 8 is changed, but part of the positional information of the paper detected a plurality of times. It is also possible to correct the misalignment based on the detection result and change the rotational speed of the transfer cylinder 8 according to the misalignment correction. That is, the number of times that the positional deviation correction is performed and the number of times that the rotational speed of the transfer cylinder 8 is changed may be smaller than the number of times that the position of the sheet is detected.

  In this embodiment, the rotational speed of the transfer drum 8 is controlled based on the detection information of the rotary encoder 82 provided in the transfer drum 8. However, as shown in the example shown in FIG. The rotational speed of the transfer cylinder 8 may be indirectly controlled by controlling a drive motor 91 provided on the paper carrying drum 9 that is interlocked with the transfer cylinder 8. In the example shown in FIG. 18, the upstream transfer cylinder 8, the paper carrying drum 9, and the downstream transfer cylinder 11 are connected via gear portions 8 a, 9 a, and 11 a provided on one end side. These are configured to be interlocked by a drive motor 91 provided on the sheet carrying drum 9. That is, the rotational speed of the upstream transfer cylinder 8 is determined in accordance with the rotational speed of the paper carrying drum 9, so that the drive motor 91 provided on the paper carrying drum 9 is provided on the upstream transfer cylinder 8. By controlling based on the detection information of the rotary encoder 82, the rotational speed of the upstream transfer cylinder 8 can be indirectly controlled.

  In the present embodiment, the downstream end detection sensor 200 is configured to be driven together (integrally) with the sandwiching roller pair 31, but the downstream end detection sensor 200 is coupled with the sandwiching roller pair 31. It is also possible to configure so as not to be driven. However, in this case, the leading edge detection position by the downstream leading edge detection sensor 200 differs depending on the skew of the sheet. For this reason, after the downstream end detection sensor 200 detects (after the target reception timing is set), when the sheet misalignment is corrected by the returning operation of the pair of clamping rollers 31 (first correction), the amount of operation of the returning operation is increased. The target reception timing varies depending on the size (the amount of skew of the paper). Therefore, in this case, in order to eliminate the influence on the target reception timing by the positional deviation correction operation (first correction), the rotational speed of the transfer cylinder 8 is changed according to the return operation (first correction), or Alternatively, it is necessary to detect the sheet conveyance timing by the downstream end detection sensor 200 after the return operation is completed.

  On the other hand, in the present embodiment, the downstream side leading edge detection sensor 200 is configured to be driven (integrally) together with the sandwiching roller pair 31. It is possible to detect in the state of facing each time (with the same posture every time). As described above, since the leading edge detection position by the downstream leading edge detection sensor 200 does not vary according to the skew of the sheet, the target reception timing is not affected by variations in the leading edge detection position. Further, since the downstream end detection sensor 200 is returned to the same position (home position) every time the clamping roller pair 31 is returned, the distance from the downstream end detection sensor 200 to the paper receiving position A is also the same every time. Become. Accordingly, there is no influence on the target reception timing due to a change in the distance from the downstream end detection sensor 200 to the paper reception position A.

  Thus, in this embodiment, since the downstream side front end detection sensor 200 is driven together with the sandwiching roller pair 31, it can be prevented from being affected by various effects when the sensor is fixed. It is not necessary to change the rotation speed of the transfer cylinder 8 in accordance with the return operation (first correction). Accordingly, it is only necessary to change the rotation speed of the transfer cylinder 8 corresponding to only the positional deviation correction (second correction) after the returning operation. Further, since the positional deviation correction (second correction) after the returning operation is a fine positional deviation correction that is performed after the positional deviation is corrected once, the change in the rotational speed of the transfer cylinder 8 usually accompanying this correction operation is also slight. Therefore, even when the sheet is conveyed at a high speed or when the conveyance distance to the sheet receiving position A is short, it is possible to cope with it sufficiently.

  Further, since the target reception timing is not affected by the return operation, the conveyance timing can be detected by the downstream end detection sensor 200 before the return operation is completed (before the start of the return operation or during the return operation). It becomes like this. Therefore, the target reception timing can be set at an early stage, and a sufficient control time for the rotational speed of the transfer cylinder 8 to be performed thereafter can be secured, thereby improving the control accuracy.

  In the present embodiment, the downstream end detection sensor 200 is disposed on the downstream side of the sandwiching roller pair 31, but in obtaining the effect of driving the downstream end detection sensor 200 together with the sandwiching roller pair 31. The downstream end detection sensor 200 may be disposed on the upstream side of the pair of nipping rollers 31.

  Further, in the present embodiment, the amount of paper misalignment correction is determined based on information from rotary encoders 57 and 58 (drive position detecting means) that detect the amount of movement in the width direction of the pair of nipping rollers 31 and the amount of rotation within the paper transport surface. Although it is obtained indirectly, it is also possible to calculate the paper misalignment correction amount from CIS information that directly detects the paper position. However, since the CIS has a large amount of information and a large load such as communication and arithmetic processing, it can be considered that it takes a long time to start changing the rotation speed of the transfer cylinder 8 from the timing when the position of the sheet is detected. . On the other hand, when the amount of paper misregistration correction is calculated indirectly based on information from the rotary encoder, the load of communication and arithmetic processing is reduced, so the rotation speed of the transfer cylinder 8 can be changed at an early timing. Can start. Therefore, even in a configuration in which the conveyance speed is fast or a configuration in which the conveyance distance to the paper receiving position A is short, it is possible to secure a control time for the rotational speed of the transfer cylinder 8 and to receive the paper with high accuracy.

  Based on FIG.19 and FIG.20, the conveying apparatus which concerns on other embodiment of this invention is demonstrated.

  In the transport apparatus according to the present embodiment, compared to the transport apparatus according to the above-described embodiment, a rotary encoder 96 that detects the transport rotational speed of the sandwiching roller pair 31 is added in FIG. 19, and in FIG. The only difference is that a step (S20) of receiving a signal from is added.

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

  Therefore, in the present embodiment, the rotation speed of the transfer cylinder 8 is determined based on the signal from the rotary encoder 82 that detects the rotation speed of the transfer cylinder 8, the movement amount in the width direction of the pair of nipping rollers 31, and the rotation amount in the sheet conveyance surface. In addition to the signals from the rotary encoders 57 and 58 for detecting the above, the signal is changed based on the signal from the rotary encoder 96 of the pair of nipping rollers 31. Thereby, even if the conveyance rotation speed of the pair of clamping rollers 31 changes, the timing of the paper and the gripper 16 on the transfer cylinder 8 can be matched, and the paper can be conveyed with higher accuracy.

  21 and 22 are a block diagram and a flowchart of a transport apparatus according to still another embodiment of the present invention.

  In the embodiment shown in FIGS. 21 and 22, a laser Doppler velocimeter 18 is used as a transported medium speed detecting unit that directly detects the transport speed of the paper. The laser Doppler velocimeter 18 is a non-contact type measuring instrument that directly measures the conveyance speed of a medium to be conveyed (paper) using the Doppler effect of light.

  In the above-described embodiment shown in FIGS. 19 and 20, a signal from the rotary encoder 96 that detects the conveyance rotation speed of the pair of clamping rollers 31 is obtained, and the conveyance speed of the paper is indirectly detected. However, in the unlikely event that a slip occurs between the sheet and the pair of nipping rollers 31, there is a possibility that the sheet conveyance speed cannot be accurately detected with the conveyance rotation speed of the nipping roller pair 31 obtained from the information of the rotary encoder 96. is there.

  Therefore, in this embodiment, instead of the rotary encoder 96 that detects the conveyance rotation speed of the pair of nipping rollers 31, the rotation speed of the transfer cylinder 8 is controlled based on the conveyance speed of the paper directly detected by the laser Doppler velocimeter 18. (S20 in FIG. 22). As a result, even if a slip occurs between the paper and the sandwiching roller pair 31, a shift in transport timing due to the slip can be prevented, and the paper can be transported with higher accuracy.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various changes can be made without departing from the scope of the present invention.

  In each of the flowcharts shown in FIGS. 16, 20, and 22, a signal from the home position sensor 80 is received in order to set the target conveyance timing, but instead of receiving the signal from the home position sensor 80. Thus, a signal from the rotary encoder 82 of the transfer cylinder 8 may be received. Even if no signal is received from the home position sensor 80, the position of the gripper 16 can be confirmed based on the signal from the rotary encoder 82 of the transfer cylinder 8, so that the target conveyance timing can be set.

  In the above-described embodiment, the receiving portion of the transfer cylinder 8 that receives the paper is the gripper 16 that swings and grips the paper. However, the receiving portion has a structure other than the structure that grips the paper, such as the gripper 16. May be.

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

  In the above-described embodiment, a case where both the positional deviation in the width direction of the paper and the positional deviation in the skew feeding are corrected is described as an example. However, the transport device according to the present invention is configured to detect the positional deviation in the width direction. The present invention can also be applied to the case where only one of the skew displacement is corrected. Even in the configuration in which only the positional deviation in the width direction is corrected, when the paper is skewed, the timing at which the leading edge of the paper reaches the downstream side leading edge detection sensor is different by correcting the positional deviation in the width direction. Therefore, the conveyance timing to the target position also varies.

  In the above-described embodiment, the transport apparatus mounted on the image forming apparatus has been described as an example of the transport apparatus according to the present invention. However, the transport apparatus according to the present invention is not limited to the transport apparatus that transports paper. Absent. The transport apparatus according to the present invention is also applicable to a transport apparatus that transports a transported medium such as an electronic substrate.

7 Conveying device 8 Transfer cylinder (conveying rotating body)
16 Gripper (receiver)
17 Rotary encoder (rotation speed detection means)
18 Laser Doppler velocimeter (conveyed medium speed detection means)
25 Rotational speed control unit 31 Nipping roller pair (position changing means)
57 Rotary encoder (drive position detection means)
58 Rotary encoder (drive position detection means)
101 1st CIS (position detection means)
102 Second CIS (position detecting means)
103 3rd CIS (position detection means)
P paper (conveyed medium)
Pa side edge

JP 2005-53646 A

Claims (14)

Position detecting means for detecting the position of the side end of the transported medium;
Depending on the position of the transported medium detected by the position detection means, while transporting the transported medium, at least one of the width direction of the transported medium and the rotation direction within the transported medium transport surface Position changing means for driving to change the position of the transported medium;
A transport rotator disposed downstream of the position changing means in the transport direction and provided with a receiving section for receiving the transported medium;
A conveying device comprising:
A transport apparatus comprising: a rotational speed control unit configured to change a rotational speed of the transport rotating body according to a position after the transport medium is changed by the position changing unit. Drive position detecting means for detecting a drive position when the position changing means is driven in at least one of a width direction of the transported medium and a rotation direction in the transported medium transport surface;
The transport apparatus according to claim 1, wherein a rotation speed of the transport rotary body is changed based on a detection result of the drive position detection unit. Rotational speed detection means for detecting the rotational speed of the transport rotating body,
The transport apparatus according to claim 1, wherein the rotational speed of the transport rotating body is changed based on a position change amount of the transported medium and a detection result of the rotational speed detection unit. A transport medium speed detecting means for directly detecting the transport speed of the transport medium;
4. The transport device according to claim 1, wherein the rotation speed of the transport rotator is changed based on a position change amount of the transported medium and a detection result of the transported medium speed detection unit. 5. . The position detecting means detects the position of the side end of the transported medium a plurality of times,
The position changing unit changes the position of the transported medium a plurality of times according to the position of the transported medium detected by the position detecting unit,
5. The rotation speed control unit according to claim 1, wherein the rotation speed control unit changes the rotation speed of the transport rotator a plurality of times in accordance with a position after the transport medium is changed by the position changing unit. Conveying device.   The number of times of changing the position of the medium to be transported by the position changing unit and the number of times of changing the rotational speed of the transport rotating body by the rotational speed control unit are smaller than the number of times of position detection by the position detecting unit. 6. The transfer device according to any one of items 1 to 5.   An image forming apparatus comprising the transport device according to claim 1. According to the detected position of the side edge of the transported medium, the transported medium is moved in at least one of the width direction and the rotation direction in the transported medium transport surface while transporting the transported medium. And changing the position of the medium to be transported, and then receiving and transporting the medium to be transported by a transport rotating body,
Depending on the position after the change of the transported medium when the transported medium is moved in at least one of the width direction and the rotation direction within the transported medium transport surface, the rotational speed of the transport rotating body is changed. A conveying method characterized by changing. While the transported medium is transported by the position changing means, the position changing means is driven in at least one of the width direction of the transported medium and the rotation direction in the transported medium transport surface to Change the position,
Detecting a driving position when the position changing unit is driven in at least one of a width direction of the transported medium and a rotation direction in a transported medium transport surface;
The transport method according to claim 8, wherein the rotation speed of the transport rotating body is changed based on the detected drive position of the position changing unit.   The transport method according to claim 8 or 10, wherein the rotation speed of the transport rotator is changed based on a position change amount of the transport medium and a rotation speed of the transport rotator.   11. The rotation speed of the transport rotator is changed based on a position change amount of the transport medium and a detection result obtained by directly detecting the transport speed of the transport medium. Transport method. In accordance with the position of the side edge of the transported medium detected a plurality of times, the transported medium is moved in at least one of the width direction and the rotation direction in the transported medium transport surface, and the transported medium is moved. Change the position of the medium multiple times,
12. The transport method according to claim 8, wherein the rotation speed of the transport rotator is changed a plurality of times according to the position after the change of the transport medium.   The number of times of changing the position of the transported medium and the number of times of changing the rotational speed of the transport rotating body are smaller than the number of times the position of the side end of the transported medium is detected. The transport method according to any one of the above items.   An image forming method, comprising: transporting a transported medium by the transport method according to claim 8, and forming an image on the transported medium.

Images