JP7185843B2 - CONVEYING APPARATUS, IMAGE FORMING APPARATUS, CONVEYING METHOD, AND IMAGE FORMING METHOD - Google Patents

Description

The present invention relates to a conveying device for conveying a medium to be conveyed, an image forming apparatus including the conveying device, a conveying method for conveying a medium to be conveyed, and an image forming method using the conveying method.

2. Description of the Related Art As a conveying device for conveying a medium to be conveyed, for example, a conveying device for conveying a sheet such as paper or a document in an image forming apparatus such as a copier or a printer is known.

Conventionally, in this type of conveying apparatus, when a sheet is conveyed to an image forming section or an image transferring section, the conveyed sheet is abutted against the nip of a conveying roller pair that is stopped to correct the skew of the sheet. After that, the sheet is conveyed to the target position by starting rotation of the conveying roller pair at a predetermined timing. However, the method of abutting the sheet against the nip of the conveying roller pair involves temporarily stopping the sheet, which poses a problem of reduced productivity (image forming speed).

In order to solve this problem, Japanese Patent Application Laid-Open No. 2005-53646 discloses a method in which a conveying roller is operated while conveying a sheet so as to correct misalignment such as skew of the sheet without lowering productivity. A conveying device has been proposed that corrects the positional deviation of the sheet without stopping the sheet by driving the pair in a direction opposite to the sheet positional deviation direction.

Specifically, in the conveying apparatus described in Patent Document 1, as shown in FIG. 26, a pair of skew detection sensors 700 arranged in a direction perpendicular to the conveying direction of the sheet 900 (the direction indicated by the dashed-dotted 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. 27, the misalignment (skew) of the sheet 900 is corrected by tilting the conveying roller pair (registration roller pair) 800 according to the calculated skew amount θ.

By the way, correcting the positional deviation of the sheet while conveying the sheet as described above changes the position of the leading edge of the sheet, so the time required for the leading edge of the sheet to reach a predetermined target position changes. Therefore, when the sheet is conveyed at a preset conveying speed, the timing at which the sheet reaches the target position is shifted, and the problem arises that the sheet cannot be conveyed with high accuracy.

Therefore, in the conveying apparatus disclosed in Japanese Patent Application Laid-Open No. 2002-200013, in order to eliminate the deviation of the sheet arrival timing due to the correction of the positional deviation of the sheet, the leading end position of the sheet after the positional deviation correction is calculated from the amount of the positional deviation of the sheet. The sheet conveying speed is adjusted based on the result.

However, in the conveying device described in Patent Document 1, after the leading edge of the sheet passes the skew detection sensor, it becomes impossible to detect the skew of the sheet. That is, skew detection can be performed only once for one sheet. Therefore, since the positional deviation correction of the sheet can be performed only once, there is a problem that the sheet cannot be conveyed with high accuracy if the sheet is further misaligned after the positional deviation correction.

In order to solve the above-mentioned problems, the present invention provides position detection means for detecting the position of a side edge of a medium to be transported, and a position of the medium to be transported according to the position of the medium to be transported detected by the position detection means. and a position changing means for changing the position of the medium to be transported a plurality of times by driving the medium in at least one of the width direction of the medium to be transported and the rotational direction in the surface of the medium to be transported while transporting the medium. A conveying device, wherein the conveying speed control unit changes the conveying speed of the medium to be conveyed each time the position of the medium to be conveyed changes by the position changing means , and changes the conveying speed of the medium to be conveyed a plurality of times. characterized by comprising

According to the present invention, the position of the medium to be transported is detected by the position detecting means, the position of the medium to be transported is changed a plurality of times according to this, and the transport speed is changed accordingly, whereby the It is possible to accurately transport the medium at the target transport timing.

1 is a schematic configuration diagram of an inkjet image forming apparatus according to an embodiment of the present invention; FIG. It is a top view of the conveying apparatus which concerns on this embodiment. FIG. 4 is a side view of a drive mechanism that drives the nipping roller pair; FIG. 4 is a plan view of a drive mechanism that drives the nipping roller pair; (a) is a diagram showing a state in which the holding frame moves only in the width direction, (b) is a diagram showing a state in which the holding frame moves only in the rotational direction within the paper transport plane, and (c) is a diagram showing the state in which the holding frame moves in the width direction. FIG. 10 is a diagram showing a state in which the roller has moved in both directions of the sheet conveying plane and the rotational direction in the sheet conveying plane; It is a block diagram showing a control system of the conveying device according to the present embodiment. FIG. 10 is a diagram showing a method of calculating a positional deviation amount from sheet positional information obtained using two CISs; It is a figure for demonstrating the positional deviation amount of the width direction. It is a figure which shows the movement 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 movement 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 movement 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 movement 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 movement 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 movement 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 the conveying apparatus which concerns on this embodiment. It is a figure which shows the flowchart of a conveyance speed control method. FIG. 10 is a diagram for explaining 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. It is a figure which shows the flowchart of the conveying apparatus which concerns on 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. 1 is a diagram showing an example in which a conveying device according to the present invention is applied to an electrophotographic image forming apparatus; FIG. It is a figure which shows the example which applied the conveying apparatus which concerns on this invention to a post-processing apparatus. FIG. 11 is a plan view of a conventional conveying device; FIG. 11 is a plan view of a conventional conveying device;

The present invention will be described below with reference to the accompanying drawings. In addition, in each drawing for explaining the present invention, constituent elements such as members and constituent parts having the same function or shape are given the same reference numerals as much as possible, and once explained, the explanation will be repeated. omitted.

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

[overall structure]
An ink jet image forming apparatus 100 according to this embodiment mainly includes a paper feed section 1 , an image forming section 2 , a drying section 3 and a paper discharge section 4 . In the inkjet image forming apparatus 100 , an image is formed in the image forming section 2 with ink, which is a liquid for image formation, on a sheet of paper P supplied from the paper feeding section 1 . After drying the ink adhering to the paper P in the drying unit 3 , the paper P is discharged from the paper discharge unit 4 . In the case of double-sided printing, after an image is formed on the front side of the sheet P in the image forming section 2, the drying section 3 performs a drying process and conveys the sheet P to the reverse conveying path 150 without discharging the sheet. do. By passing through the reversing conveyance path 150, the paper P is supplied to the image forming section 2 again in a state where the front and back are reversed, and after an image is formed on the back surface of the paper P in the image forming section 2, it is sent to the drying section. Drying processing is performed in 3 and the paper is discharged from the paper discharge unit 4 .

[Paper feed section]
The paper feeding unit 1 mainly includes a paper feeding tray 5 on which a plurality of papers P are stacked, a feeding device 6 that separates and feeds the papers P one by one from the paper feeding tray 5, and an image forming unit that feeds the papers P. 2, and a conveying device 7 that feeds it into. As the feeding device 6, it is possible to use any feeding device such as a device using rollers or rollers, or a device using air suction. The sheet P sent out from the sheet feeding tray 5 by the feeding device 6 is transported to the image forming section 2 by the transporting device 7 .

[Image forming section]
The image forming section 2 mainly includes a transfer drum 8 as a first conveying rotating body that receives the fed paper P and transfers it to the paper carrying drum 9, and the paper P conveyed by the transfer drum 8 on the outer peripheral surface. A paper carrier drum 9 as a second transport rotating body that carries and transports the paper P, an ink ejection unit 10 that ejects ink toward the paper P carried by the paper carrier drum 9 , and the paper transported by the paper carrier drum 9 . It is composed of a transfer cylinder 11 as a third conveying rotating body for transferring the paper P to the drying section 3 .

The paper P conveyed from the paper feeding section 1 to the image forming section 2 is gripped at its leading end by a swingable gripper 16 as a gripping section provided on the surface of the transfer cylinder 8, and the surface of the transfer cylinder 8 is moved. transported with it. The paper P conveyed by the transfer drum 8 is transferred to the paper carrying drum 9 at a position facing the paper carrying drum 9 .

A similar gripper is provided as a gripping portion on the surface of the paper carrying drum 9, and the tip of the paper is gripped by the gripper. A plurality of suction holes are formed in a dispersed manner on the surface of the paper carrying drum 9 , and a suction device 12 generates a suction air current toward the inside of the paper carrying drum 9 in each of the suction holes. The paper P transferred from the transfer drum 8 to the paper carrying drum 9 is gripped by the gripper at the leading end, is attracted to the surface of the paper carrying drum 9 by the suction air current, and is moved along with the movement of the surface of the paper carrying drum 9. be 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. It has individual liquid ejection heads 10C, 10M, 10Y, and 10K. The liquid ejection heads 10C, 10M, 10Y, and 10K are not limited in their configuration as long as they eject liquid, and any configuration can be adopted. If necessary, a liquid ejection head for ejecting special ink such as white, gold, or silver may be provided, or a liquid ejection head for ejecting liquid that does not form an image, such as a surface coating liquid, may be provided.

The ejection operations of the liquid ejection heads 10C, 10M, 10Y, and 10K of the ink ejection section 10 are controlled by drive signals corresponding to image information. When the paper P carried on the paper carrying drum 9 passes through the area facing the ink ejection section 10, the liquid ejection heads 10C, 10M, 10Y, and 10K eject inks of respective colors, and an image corresponding to the image information is produced. It is formed. Note that, in the present embodiment, the image forming section 2 is not limited in its configuration as long as it forms an image by depositing liquid on the paper P. FIG.

[Drying section]
The drying unit 3 is mainly composed of a drying mechanism 13 for drying 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. It is The paper P conveyed from the image forming section 2 is received by the conveying mechanism 14 , conveyed so as to pass through the drying mechanism 13 , and delivered to the paper discharging section 4 . When the paper P passes through the drying mechanism 13, the ink on the paper P is subjected to a drying process, whereby liquids such as moisture in the ink evaporate, the ink adheres to the paper P, and the paper P curls. Suppressed.

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

[Other additional functions]
The inkjet image forming apparatus 100 according to the present embodiment includes a paper feeding section 1, an image forming section 2, a drying section 3, and a paper discharging section 4, but other functional sections may be added as appropriate. For example, a preprocessing unit for performing preprocessing for image formation may be added between the paper feeding unit 1 and the image forming unit 2, or post-processing for image formation may be performed between the drying unit 3 and the paper discharge unit 4. Processing units can be added.

Examples of the pretreatment unit include those that perform a treatment liquid coating process for applying a treatment liquid to the paper P for suppressing bleeding by reacting with ink, but there are no particular restrictions on the content of the pretreatment. . Further, as a post-processing unit, for example, a paper reversal conveying process for reversing the paper P on which an image is formed in the image forming unit 2 and feeding it again to the image forming unit 2 to form images on both sides of the paper P, , binding a plurality of sheets of paper P on which images have been formed, and the like, but there are no particular restrictions on the content of the post-processing.

Note that the "image" formed on the paper is not limited to visualizing significant images such as characters and graphics, and includes, for example, patterns that have no meaning per se. In addition, the "sheet" on which the image is formed is not limited in material, and can be made of paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc., to which liquid can adhere even temporarily. For example, it may be used for film products, cloth products such as clothing, building materials such as wallpaper and flooring, and leather products. Further, the "liquid" is not particularly limited as long as it has a viscosity and surface tension that can be ejected from the head, but the viscosity is 30 mPa s or less at normal temperature and pressure, or by heating or cooling. Preferably. More specifically, solvents such as water and organic solvents, colorants such as dyes and pigments, functional-imparting materials such as polymerizable compounds, resins, and surfactants, biocompatible materials such as DNA, amino acids, proteins, and calcium. , edible materials such as natural pigments, and the like, which can be used for applications such as inkjet inks and surface treatment liquids.

Further, the "inkjet image forming apparatus" includes an apparatus in which a liquid ejection head and a sheet material move relatively, but is not limited to this. Specific examples include a serial type apparatus in which the liquid ejection head is moved and a line type apparatus in which the liquid ejection head is not moved.

A "liquid ejection head" is a functional component that ejects and ejects liquid from ejection holes (nozzles). Piezoelectric actuators (laminated piezoelectric element and thin film piezoelectric element), thermal actuators using electrothermal conversion elements such as heating resistors, and electrostatic actuators consisting of a vibration plate and a counter electrode are used as energy sources for liquid ejection. Energy generating means can be used, but the ejection energy generating means to be used is not limited.

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

FIG. 2 is a plan view of the conveying device according to this 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, 220, and a nipping roller pair 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, in order from the upstream side in the paper transport direction, a first CIS (first position detection means) 101, a second CIS (second position detection means) 102, and a third CIS. It will be called CIS (third position detecting means) 103 . Of the two leading edge detection sensors 200 and 220, the leading edge detection sensor 200 arranged downstream of the nipping roller pair 31 is called a downstream leading edge detection sensor (first conveying timing detection means). The leading edge detection sensor 220 arranged on the upstream side will be referred to as an upstream leading edge detection sensor (second conveying timing detection means).

In recent years, CIS uses a small-shaped LED (Light Emitting Diode) as a light source for the purpose of miniaturizing the device, and a contact image sensor (Contact Image) that directly reads an image with a linear sensor through a lens. Sensor). Each of the CISs 101 to 103 can detect a side edge Pa on one side of the paper P in the width direction by using a plurality of line sensors provided in the width direction of the paper P. FIG. The first CIS 101 and the second CIS 102 are arranged upstream of the pair of nipping rollers 31 and downstream of the pair of conveying rollers 44 , one upstream of the pair of nipping rollers 31 . On the other hand, the third CIS 103 is arranged downstream of the nipping roller pair 31 and upstream of the transfer cylinder 8 . Further, the CISs 101 to 103 are arranged parallel to the width direction of the paper P (the direction perpendicular to the transport direction).

Each of the leading edge detection sensors 200 and 220 is composed of a reflective optical sensor or the like. The upstream edge detection sensor 220 is arranged upstream of the nipping roller pair 31 and downstream of the second CIS 102 . The downstream edge detection sensor 200 is arranged downstream of the nipping roller pair 31 and upstream of the third CIS 103 . When the paper P is conveyed, the leading edge Pb of the paper P is detected by the upstream leading edge detection sensor 220, and the timing at which the leading edge Pb of the paper P reaches the upstream leading edge detection sensor 220 is detected. be. After the paper P is nipped by the nipping roller pair 31, when the leading edge Pb of the paper P reaches the position of the downstream edge detection sensor 200, the downstream edge detection sensor 200 detects the leading edge Pb of the paper P. , the timing at which the leading edge Pb of the sheet P reaches the downstream leading edge detection sensor 200 is detected.

The nipping roller pair 31 moves in the width direction of the paper P (the direction of the arrow S in FIG. 2) while nipping the paper P being transported, or moves around the support shaft 73 within the paper transport plane ( (in the direction of the 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 the oblique feeding direction are corrected. In other words, the nipping roller pair 31 functions as positional deviation correcting means for correcting the positional deviation of the paper P. As shown in FIG. In this embodiment, the support shaft 73 is provided at one axial end of the nipping roller pair 31 , but the support shaft 73 may be provided at the center position of the nipping roller pair 31 in the axial direction.

3 and 4 show the configuration of a driving mechanism for driving the nipping roller pair. 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 nipping roller pair 31 is composed of a drive roller 31a that is rotationally driven around the roller shaft and a driven roller 31b that is driven to rotate therewith. These nipping roller pairs 31 are held by a holding frame 72 as a holding member so as to be rotatable about the roller shafts. 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 support member. Accordingly, the holding frame 72 is configured to be movable in any direction within the paper transport plane (transported medium transport plane) along the upper surface of the base frame 71 . By supporting the holding frame 72 using the free bearings 95 in this way, the friction load when the holding frame 72 moves can be made extremely small. As a result, sheet misalignment correction, which will be described later, can be performed 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.

As shown in FIG. 3, the holding frame 72 is provided with the support shaft 73 extending downward as the rotation center of the nipping roller pair 31 in the sheet conveying plane. A lower end portion of the support shaft 73 is inserted into a width direction guide portion 71 a formed in the base frame 71 . The width direction guide portion 71a is a hole formed to extend substantially linearly in the width direction (direction of arrow S in FIG. 4). A guide roller 79 is rotatably provided at the lower end of the support shaft 73, and the support shaft 73 is inserted through the guide roller 79 so as to come into 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 nipping roller pair 31 held thereon also move in the width direction. The holding frame 72 is also configured to rotate (in the direction of arrow W in FIG. 4) within the paper transport plane about the support shaft 73 . As the holding frame 72 rotates about the support shaft 73, the nipping roller pair 31 rotates within the sheet conveying plane.

As shown in FIG. 3, a bracket 69 provided on the right end side of the main body frame 70 in the drawing has a transport driving motor (transport driving means) 61 for applying a driving force to the nipping roller pair 31 for transporting the paper. is provided. The conveying driving motor 61 and the driving roller 31 a of the nipping 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 maintains the connection so that the driving force can be transmitted even when the rotation shaft of the drive roller 31a and the rotation shaft of the gear 67 are separated from each other in the axial direction, come close to each other, or are driven in mutually inclined directions. It is a two-stage spline coupling. Since the drive roller 31a and the gear 67 are coupled via the coupling mechanism 65 in this way, the nipping roller pair 31 moves in the width direction and rotates within the sheet conveying plane, thereby moving the drive roller 31a. and the transport drive motor 61, the driving force can be transmitted satisfactorily from the transport drive motor 61 to the drive roller 31a.

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

Further, the conveying device 7 according to the present embodiment includes a width direction driving mechanism 38 that moves the holding frame 72 and the nipping roller pair 31 in the width direction, and an oblique driving mechanism that rotates the holding frame 72 and the nipping roller pair 31 within the sheet conveying plane. and a row-direction drive mechanism 39 .

As shown in FIGS. 3 and 4, the width direction driving mechanism 38 is composed of a width direction driving motor (width direction driving 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 around its rotary shaft 45a. The cam 45 is held in contact with a 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, thereby moving the holding frame 72 in the width direction (rightward in FIG. 4).

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

As shown in FIGS. 3 and 4, the skew direction driving mechanism 39 includes a skew direction driving motor (skew direction driving 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 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 around its rotary 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 biasing force of the tension spring 60 . A working roller 49 is rotatably provided at the opposite end of the lever member 50 . The action roller 49 is held in contact with a protrusion 72 a provided on the holding frame 72 by the biasing 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 its rotation axis 50a. Along with this, the action roller 49 provided on the lever member 50 pushes the protrusion 72a of the holding frame 72 against the biasing force of the tension spring 60, so that the holding frame 72 moves within the sheet conveying plane (FIG. 4). counterclockwise in).

Further, as shown in FIG. 3, a timing belt 98 is stretched between the rotating shaft 47a of the cam 47 and the motor shaft of the oblique direction driving motor 63. As shown in FIG. As a result, the drive force is transmitted from the oblique direction drive motor 63 to the cam 47 via the timing belt 98 . A rotary encoder 58 is provided on the rotary shaft 47 a of the cam 47 as a rotation angle detection means for detecting the rotation angle (rotation amount) of the cam 47 . By controlling the driving of the oblique direction driving 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 within the sheet conveying plane is adjusted. That is, the rotary encoder 58 functions as driving position detecting means for detecting the driving position when the holding frame 72 and the nipping roller pair 31 rotate within the sheet conveying plane.

FIG. 5(a) shows a state in which only the cam 45 of the width direction driving mechanism 38 rotates and the holding frame 72 moves in the width direction, and FIG. 5(b) shows the oblique direction driving mechanism. Only the cam 47 of 39 is rotated, and the holding frame 72 is rotated within the sheet conveying plane. FIG. 5(c) shows a state in which both the cams 45 and 47 are rotated, and the holding frame 72 is moved in the width direction and rotated within the sheet conveying plane.

Further, 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 or rotates in the paper conveying plane as described above, the downstream edge detection sensor 200 moves (integrally) with the holding frame 72 in the width direction or the paper conveying surface. move within. On the other hand, the upstream edge detection sensor 220 is fixed so as not to move on the conveying path.

FIG. 6 is a block diagram showing the control system of the conveying device according to this embodiment.

As shown in FIG. 6, the conveying apparatus according to the present embodiment includes the conveying drive motor 61 for applying a driving force for conveying the sheet to the nipping roller pair, and the width direction driving motor 61 for driving the nipping roller pair in the width direction. A control section 20 is provided for independently controlling the motor 62 and the skew direction driving motor 63 for rotating the nipping roller pair within the sheet conveying plane. That is, the control unit 20 controls the rotation speed of the nipping roller pair, the amount of movement in the width direction, and the amount of rotation within the sheet conveying plane.

The control unit 20 includes a positional deviation calculation unit 21 that calculates the positional deviation amount of the paper based on the detection results of the CISs 101 to 103, and the detection result of the downstream edge detection sensor 200 and the home position provided on the transfer cylinder 8. A target transport timing calculation unit 22 that calculates a target transport timing of the paper to a predetermined target position based on the detection result of the sensor 80 (see FIG. 1), and a paper transport speed ( and a conveying speed control unit 23 for controlling the conveying rotation speed of the nipping roller pair 31 . The transport speed control unit 23 also controls information from a rotary encoder 96 that detects the transport rotation speed of the nipping roller pair 31, and each rotary sensor that detects the amount of movement of the nipping roller pair 31 in the width direction and the amount of rotation in the sheet transport plane. The conveying speed is also corrected based on information from the encoders 57 and 58 .

In this embodiment, the paper P is positioned at the paper gripping position A in time with the timing when the gripper 16 provided on the transfer drum 8 rotating at a constant speed reaches the paper gripping position A on the transfer drum 8 (see FIG. 1). is required to reach The timing at which the gripper 16 reaches the paper gripping position A can be specified by detecting the rotation reference position C of the transfer cylinder 8 with the home position sensor 80 . Although only one gripper 16 is shown in the example shown in FIG. 1, a plurality of grippers 16 may be provided on the transfer drum 8. Further, in the present embodiment, the paper P is adjusted to the same speed each time at the target position B (see FIG. 1) slightly before the paper gripping position A (in the vicinity of the upstream side), and thereafter, at the same speed, at the paper gripping position. Transported to reach A. Therefore, in this 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 adjustment of the transport speed of the paper P is completed is set as the target position B. The final target transport position may be set to the target position B if there is no need to transport at . The calculated target transport timing may be, for example, the time from when the leading edge Pb of the paper P is detected by the downstream leading edge detection sensor 200 until the paper P reaches the target position B at a predetermined timing. However, the conveying rotation speed of the nipping roller pair 31 may be such that the sheet P can reach the target position B in this time.

Here, a method for calculating the amount of sheet misregistration will be described with reference to FIGS. 7 and 8. FIG. Note that FIG. 7 shows a method of calculating the amount of sheet misalignment using the first CIS 101 and the second CIS 102. The method of calculating the deviation amount is also the same.

As shown in FIG. 7, when the leading edge Pb of the paper P passes through the first CIS 101 and reaches the second CIS 102, the amount of misalignment α in the width direction of the paper P and the amount of misalignment β in the skewing direction are different. 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 edge Pa in the width direction of the sheet P) detected by the second CIS 102 . That is, the position in the width direction detected by the second CIS 102 is compared with the transport reference position K, and the distance K1 in the width direction between them is the positional deviation amount α of the paper P in the width direction.

Further, the skew positional deviation β is calculated from the difference between the widthwise edge positions of the sheet P detected by the first CIS 101 and the second CIS 102 . That is, as shown in FIG. 7, when the leading edge Pb of the sheet P reaches the second CIS 102, the first CIS 101 and the second CIS 102 move the distances K1 and K2 in the width direction from the conveyance reference position K. is detected. Then, from these distances K1 and K2 and the preset distance M1 between the first CIS 101 and the second CIS 102, using the formula tanβ=(K1−K2)/M1, the skew is calculated.

In this manner, the widthwise positional deviation amount α and the oblique positional deviation amount β are calculated. As shown in FIG. 8, when the sheet is moved from the position P to the position P' by correcting the positional deviation of the skew, the positional deviation amount in the width direction changes from α to α'. Therefore, by calculating the positional deviation amount α' in the width direction in advance, it is possible to perform positional deviation correction with higher accuracy. However, the amount of positional deviation α′ in the width direction changes depending on which position is used as a reference for the skewed positional deviation correction.

Next, the operation of the conveying apparatus according to this embodiment will be described with reference to the plan views and side views of FIGS. 9 to 14 and the flowchart of FIG.

As shown in FIGS. 9A and 9B, when the sheet P is conveyed, the nipping roller pair 31 is arranged at the home position where the roller shafts are perpendicular to the conveying direction (horizontal direction in the drawing). ing. Also, in this state, the nipping roller pair 31 is separated from each other and stands by in a stationary state.

After that, as shown in FIGS. 10A and 10B, when the leading edge Pb of the paper P passes through the first CIS 101 and reaches the second CIS 102, the first CIS 101 and the second CIS 102 move the paper. "First position detection" is performed to detect the position of the side end Pa of P (S1 in FIG. 15). Then, based on the positional 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 accompanying the correction of the skewed positional deviation) and the skewed position are calculated. is calculated by the positional displacement amount calculator 21 (see FIG. 6). Then, based on the calculated positional deviation amount, the width direction driving motor 62 and the skew direction driving motor 63 are controlled to move the nipping roller pair 31 in the width direction (in the direction of the arrow S1 in FIG. 10) and move the paper. Rotate within the transport plane (in the direction of arrow W1 in FIG. 10). As a result, the nipping roller pair 31 is moved to face the leading edge Pb of the paper P (S2 in FIG. 15).

Then, the leading edge portion Pb of the sheet P is detected by the upstream leading edge detection sensor 220, and based on the detection timing, the nipping roller pair 31 comes into contact with each other and the conveying rotation is started. After that, as shown in FIGS. 11A and 11B, the sheet P is received by the pair of nipping rollers 31 facing each other, and conveyed while being nipped by the pair of nipping rollers 31 . Incidentally, when the sheet P is delivered to the nipping roller pair 31, the transport roller pair 44 on the upstream side of the nipping roller pair 31 is separated from each other.

Further, as shown in FIGS. 11A and 11B, when the sheet P is transported by the nipping roller pair 31 and the leading edge portion Pb of the sheet P reaches the position of the downstream edge detection sensor 200, the downstream edge detection sensor The leading edge Pb of the paper P is detected by 200 (S3 in FIG. 15). As a result, the timing at which the leading edge portion Pb of the sheet P reaches the downstream leading edge detection sensor 200 is detected. Then, based on the detection result of the downstream edge detection sensor 200 and the detection result of the home position sensor 80 of the transfer drum 8, the target conveyance timing of the sheet to the predetermined target position B is determined by the target conveyance timing calculator 22 (FIG. 6) and is set (S4 in FIG. 15).

Thereafter, as shown in FIGS. 12A and 12B, while conveying the sheet P by the pair of nipping rollers 31, the pair of nipping rollers 31 is moved in the direction opposite to the welcoming operation (direction of arrow S2 and direction of arrow W2 in the figure). A return operation is performed to drive to (S5 in FIG. 15). As a result, the "first correction" for correcting the positional deviation in the width direction and the skewed positional deviation of the paper P is performed.

Furthermore, as shown in FIGS. 13A and 13B, when the leading edge Pb of the paper P reaches the third CIS 103, the second CIS 102 and the third CIS 103 move the side edge Pa of the paper P again. "Second position detection" is performed to detect the position (S6 in FIG. 15). Based on the positional information detected by these CISs 102 and 103, the positional deviation amount in the width direction and the skewed positional deviation amount are calculated by the positional deviation amount calculation unit 21. FIG. Then, based on the calculated positional deviation amount, the width direction driving motor 62 and the skew direction driving motor 63 are controlled to move the nipping roller pair 31 in the width direction (in the direction of arrow S3 or arrow S4 in FIG. 13). "Second correction" is performed to correct the positional deviation of the paper P by moving and rotating it (in the direction of arrow W3 or W4 in FIG. 13) within the paper transport plane (S7 in FIG. 15).

In this way, even after the returning operation (first correction), the positional deviation of the paper P is detected (second position detection), and based on the detection result, the positional deviation of the paper P is corrected (second correction ), it is possible to eliminate the positional deviation that occurs while the sheet P is conveyed by the nipping roller pair 31 . Further, positional deviation detection (second position detection) after such return operation can be performed multiple times at predetermined intervals while the paper is passing through the second CIS 102 and the third CIS 103 . Therefore, by performing such positional deviation detection (second positional detection) a plurality of times and performing positional deviation correction (second correction) each time, it is possible to convey the paper with higher accuracy.

However, if the positional deviation correction (second correction) as described above is performed after the returning operation, the position of the paper in the conveying direction will change accordingly. 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 return operation, each time the positional deviation correction is performed, a to change (correct) the transport speed of the paper P (S8 in FIG. 15). 14A and 14B, the paper P is transported further downstream at the changed transport speed so that the gripper 16 reaches the paper gripping position A at the timing shown in FIGS. Then, the paper P is conveyed to the paper gripping position A (S9 in FIG. 15). Then, when the paper P reaches the paper gripping position A, the nipping roller pair 31 separates from each other, and the transportation of the paper by the nipping roller pair 31 is completed. If there is no positional deviation of the paper after the returning operation and the positional deviation correction (second correction) is not performed, the arrival timing of the paper to the target position B basically does not change. No change in the transport speed corresponding to the 2 correction) is performed.

A method of controlling the conveying speed will be described below with reference to the flow chart of FIG.

As shown in FIG. 16, when the control of the nipping roller pair 31 is started, first, the gripper 16 rotates based on the detection result of the home position sensor 80 of the transfer drum 8 before the target conveying timing is set. It is confirmed that the robot is at the reference position C (S11 in FIG. 16). Then, the leading edge of the sheet is detected by the downstream leading edge detection sensor 200 as described above (S12 in FIG. 16), and the target transport timing is determined 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 nipping roller pair 31 is calculated according to the set target transport timing (S14 in FIG. 16). The calculation of the target rotation speed of the nipping roller pair 31 may be performed by the target conveying timing calculation unit 22 or may be performed by another calculation unit. Then, the conveying rotation speed of the nipping roller pair 31 is controlled based on the calculated target rotation speed (S15 in FIG. 16). In this embodiment, the conveying rotational speed of the nipping roller pair 31 is managed based on a signal from a rotary encoder 96 provided on the nipping roller pair 31 . Therefore, in order to determine whether the conveying rotation speed of the nipping roller pair 31 is faster or slower than the target rotation speed, the conveying speed control unit 23 acquires the signal from the rotary encoder 96 (S16 in FIG. 16). .

Further, when the positional deviation correction (second correction) is performed by the nipping roller pair 31 after setting the target transport timing, the nipping roller pair 31 conveys the sheet based on the positional deviation correction amount associated with the positional deviation correction. Change the rotation speed. This positional deviation correction amount corresponds to the driving position (driving amount and driving direction) at which the nipping roller pair 31 is driven in the width direction or the rotational direction within the sheet conveying surface when the positional deviation is corrected. Therefore, in the present embodiment, the conveying speed control unit 23 acquires signals from the respective rotary encoders 57 and 58 for detecting the width direction of the nipping roller pair 31 and the driving amount and driving direction within the sheet conveying surface (see FIG. 16). S17). Based on the target transfer timing and the signals from the rotary encoders 96, 57 and 58, the target rotation speed for transfer is changed (S14 in FIG. 16). Then, the conveying rotation speed of the nipping roller pair 31 is controlled based on the newly calculated target rotation speed (S15 in FIG. 16). Then, the control of the conveying rotation speed as described above is performed until the sheet conveying time reaches the target conveying timing (S18 in FIG. 16). The paper is conveyed to the paper gripping position A at the same speed as the conveying rotation speed (S19 in FIG. 16). As a result, the conveying speed can be changed according to the positional deviation correction amount of the sheet, and the sheet can be conveyed to the sheet gripping position A with good timing and high accuracy.

A method of calculating the positional change amount of the paper accompanying the positional deviation correction will be described with reference to FIG. 17 .

In FIG. 17, point Z is the position of the center of rotation (support shaft 73) in the sheet conveying plane when the nipping roller pair 31 is arranged at the home position, point R is the measurement reference point, and point Q is The position of the leading edge of the paper when time t has passed since the leading edge of the paper was detected by the downstream leading edge detection sensor 200, point Q', is corrected at the timing (time t-1) one before time t. Indicates the position of the leading edge of the paper when Also, in FIG. 17, characters in parentheses indicate points Z, Q, X and Y coordinates of Q'. θ is the inclination angle (rotational angle in the paper transport plane) from the home position of the nipping roller pair 31 when the leading edge of the paper reaches the position of point Q, ' is the angle of inclination from the home position of the nipping roller pair 31 (the angle of rotation within the sheet conveying plane). Δθ is the difference between these tilt angles θ and θ'.

In this way, when the position of the leading edge of the paper P changes with the positional deviation correction operation, the position coordinates (Qx, Qy) of the leading edge position Q of the paper at time t are obtained using the following equations 1 and 2. can be calculated by

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

Xp in Equation 1 above is the X-direction component of the transport distance by which the paper P is transported up to the timing (time t−1) immediately before time t, and Yp in Equation 2 above is the component of the transport distance. It is the Y-direction component of the conveying distance. Letting Fp be the transport distance (transport distance in the direction orthogonal to the roller axis) over which the paper P is transported by the nipping roller pair 31 during time t−1, Xp and Yp are expressed by the following equations 3 and 4. be able to. Ys in Equation 2 is the amount of movement of the paper P in the width direction (the amount of movement in the Y direction) from the point Q' to the point Q.

Xp=cos(θ')Fp Expression 4
Yp=sin(θ')Fp Expression 5

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

Then, the position change amount G is calculated (see Equation 5 below). By adjusting the transport speed to the target position based on the position change amount G thus calculated, the paper can be transported to the target position at a predetermined transport timing.

G=Qx-Vx Expression 5

As described above, according to the conveying apparatus according to the present embodiment, since the CIS for detecting the position of the side edge of the sheet is used as the position detecting means for detecting the position of the sheet, As in positional deviation correction (second correction), the side edges of the paper can be detected multiple times by the CIS while the paper is passing through the CIS. In this way, by using the CIS, it is possible to detect the position of the paper multiple times. be able to do so with precision. In addition, even if the position of the paper in the transport direction changes due to the positional deviation correction, the positional deviation correction amount (the position of the paper in the width direction and the rotational direction in the paper transport plane) is changed every time the positional deviation correction is performed. By changing the transport speed of the paper based on the amount of change), the paper can be transported to the target position at a predetermined timing. In other words, the change in the position of the sheet in the conveying direction caused by multiple misregistration corrections is not dealt with by changing the conveying speed once, but by changing the conveying speed every time the misregistration is corrected. By doing so, it is possible to adjust the conveying speed with sufficient time. As a result, the paper can be transported with high accuracy and reliably in time for the target transport timing. As a result, misalignment of the image with respect to the paper P can be prevented with high accuracy, and print quality is improved. In addition, when double-sided printing is performed, it is possible to correct the positional deviation of the image on the front side and the back side, so it is possible to eliminate the relative positional deviation between the image on the front side and the image on the back side. . In the present embodiment, positional deviation correction and transport speed change are performed each time the position of the paper is detected. Positional deviation correction may be performed based on the detection result of (1), and the conveying speed may be changed. That is, the number of times the positional deviation correction is performed and the number of times the transport speed is changed may be less than the number of times the position of the sheet is detected.

By the way, in the present embodiment, the downstream edge detection sensor 200 is configured to be driven (integrally) together with the nipping roller pair 31 . It is also possible to configure so that it is not driven to However, in that case, the leading edge detection position by the downstream leading edge detection sensor 200 differs depending on the degree of skew of the sheet. Therefore, after the position of the leading edge of the paper is detected, when the misalignment of the paper is corrected by the return operation of the nipping roller pair 31 (first correction), the magnitude of the operation amount of the return operation (the magnitude of the skew amount of the paper) Accordingly, the target transport timing fluctuates. Therefore, in order to eliminate the influence of such a positional deviation correction operation (first correction), it is necessary to detect the sheet transport timing after the return operation is completed.

On the other hand, when the downstream edge detection sensor 200 is configured to be driven (integrally) together with the nipping roller pair 31 as in the present embodiment, the downstream edge detection sensor 200 is driven with respect to the sheet. can be detected in the state where is facing each time (in the same posture each time). In this way, the leading edge detection position of the downstream leading edge detection sensor 200 does not change according to the degree of skew of the sheet, so the target transport timing is not affected by variations in the leading edge detection position. Further, since the downstream edge detection sensor 200 is returned to the same position (home position) each time as the nipping roller pair 31 is returned, the distance from the downstream edge detection sensor 200 to the target position B is also the same each time. . Therefore, the change in the distance from the downstream edge detection sensor 200 to the target position B does not affect the target transport timing.

In this way, by driving the downstream edge detection sensor 200 together with the nipping roller pair 31, it is possible to avoid various influences when the sensor is fixed, and the return operation (first correction ), there is no need to change the paper transport speed. Also, since the target transport timing is not affected by the return operation, the transport timing can be detected before the return operation is completed (before the return operation starts or during the return operation). Therefore, the target transfer timing can be set at an early stage, and a sufficient control time for the transfer speed to be performed thereafter can be secured, thereby improving the control accuracy.

In this embodiment, the downstream edge detection sensor 200 is arranged downstream of the nipping roller pair 31, but in order to obtain the effect of driving the downstream edge detection sensor 200 together with the nipping roller pair 31, Alternatively, the downstream edge detection sensor 200 may be arranged on the upstream side of the nipping roller pair 31 .

Further, according to the present embodiment, it is not necessary to change the paper transport speed accompanying the return operation. OK. Moreover, since the positional deviation correction after the returning operation (second correction) is a fine positional deviation correction performed after the positional deviation has been corrected, usually only a slight change in the conveying speed is required for this correction operation. . Therefore, even when the paper is conveyed at high speed or when the conveying distance to the target position is short, it is possible to sufficiently cope with this.

Further, in the present embodiment, the positional deviation correction amount of the paper is determined from the information of the rotary encoders 57 and 58 (driving position detection means) that detect the amount of movement of the nipping roller pair 31 in the width direction and the amount of rotation within the paper transport plane. Although it is obtained indirectly, it is also possible to calculate the positional deviation correction amount of the paper from the information of the CIS that directly detects the position of the paper. However, since the CIS has a large amount of information and a large load on communication and arithmetic processing, it is conceivable that the time from the timing when the position of the paper is detected to the time when the transport speed is changed is long. On the other hand, if the paper misalignment correction amount is indirectly calculated based on the information from the rotary encoder, the load of communication and arithmetic processing can be reduced, so it is necessary to start changing the transport speed at an early timing. can be done. Therefore, even in a configuration with a high transport speed or a configuration with a short transport distance to the target position, it is possible to secure the control time of the transport speed, and the paper can be transported with high precision.

A conveying device according to another embodiment of the present invention will be described with reference to FIGS. 18 and 19. FIG.

18, the conveying apparatus according to this embodiment has a rotary encoder 17 as rotational speed detection means for detecting the conveying rotational speed of the transfer drum 8, and in FIG. , in that a step (S20) of receiving a signal from the rotary encoder 17 is added.

Although the transfer drum 8 is basically controlled to rotate at a constant speed, it is conceivable that the conveying rotational speed of the transfer drum 8 changes for some reason. In this case, as described above, even if the conveying rotation speed of the nipping roller pair 31 is changed based on the positional deviation correction amount of the sheet, there is a possibility that the timing of the sheet and the gripper 16 on the transfer cylinder 8 do not match. .

Therefore, in the present embodiment, a signal from the rotary encoder 96 that detects the conveying rotation speed of the nipping roller pair 31, and each rotary encoder that detects the amount of movement in the width direction of the nipping roller pair 31 and the amount of rotation within the sheet conveying plane. In addition to the signals from 57 and 58, the signal from the rotary encoder 17 of the transfer drum 8 is acquired by the conveying speed control unit 23 (S16, S17, S20 in FIG. 19), and these signals, the target conveying timing, (S14 in FIG. 19). Then, the conveying rotation speed of the nipping roller pair 31 is controlled based on the newly calculated target rotation speed (S15 in FIG. 19). As a result, even if the conveying rotational speed of the transfer cylinder 8 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.

20 and 21 are block diagrams and flow charts of a transport apparatus according to another embodiment than the above-described embodiment.

In the embodiment shown in FIGS. 20 and 21, instead of receiving the signal from the home position sensor 80, a signal from the rotary encoder 17 of the transfer drum 8 is received in order to set the target transport timing. (S12 in FIG. 21). Other than that, it is the same as the embodiment shown in FIGS. It is possible to confirm the position of the gripper 16 based on the signal from the rotary encoder 17 of the transfer drum 8 even without receiving the signal from the home position sensor 80 . Therefore, in this embodiment, based on the signal reception from the downstream end detection sensor 200 (S11 in FIG. 21) and the subsequent signal reception from the rotary encoder 17 of the transfer drum 8 (S12 in FIG. 21), A target transport timing is set (S13 in FIG. 21).

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

In the embodiment shown in FIGS. 22 and 23, a laser Doppler velocimeter 18 is used as transported medium speed detection means for directly detecting the paper transport speed. The laser Doppler velocimeter 18 is a non-contact measuring instrument that directly measures the transport speed of a transported medium (paper) using the Doppler effect of light.

In the above-described embodiment, a signal is obtained from the rotary encoder 96 for detecting the conveying rotation speed of the pair of nipping rollers 31 to indirectly detect the sheet conveying speed. However, in the unlikely event that slippage occurs between the paper and the nipping roller pair 31, there is a possibility that the paper feeding speed cannot be accurately detected with the transport rotation speed of the nipping roller pair 31 obtained from the information of the rotary encoder 96. be.

Therefore, in the present embodiment, instead of the rotary encoder 96 for detecting the conveying rotational speed of the nipping roller pair 31, the conveying rotational speed of the nipping roller pair 31 is detected based on the sheet conveying speed directly detected by the laser Doppler velocimeter 18. is controlled (S20 in FIG. 23). That is, the conveying speed controller 23 receives signals from the rotary encoders 57 and 58 for detecting the amount of movement of the nipping roller pair 31 in the width direction and the amount of rotation in the sheet conveying plane, and the signal from the laser Doppler velocimeter 18. (S17 and S20 in FIG. 23), and changes the target rotation speed based on these signals and the target transport timing (S14 in FIG. 23). Then, the conveying rotation speed of the nipping roller pair 31 is controlled based on the newly calculated target rotation speed (S15 in FIG. 23). As a result, even if slippage occurs between the paper and the pair of nipping rollers 31, it is possible to prevent deviation of the conveying timing due to the slippage and convey the paper with higher accuracy.

In addition, in the example using the laser Doppler velocimeter 18 as in the present embodiment, furthermore, as in the examples shown in FIGS. You may change the conveying speed by In this case, in addition to preventing deviation of the transport timing caused by slippage between the paper and the pair of nipping rollers 31, it is possible to prevent deviation of the transport timing caused by fluctuations in the transport rotation speed of the transfer drum 8. Accurate transportation can be realized.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

In the above-described embodiment, the CIS is used as the position detection means for detecting the position of the side edge of the paper. Other detection means may be used as long as the side edge can be detected.

Further, in the above-described embodiment, the case of correcting both the positional deviation in the width direction and the positional deviation in the oblique feeding of the paper has been described as an example. It can also be applied to the case of correcting only one of skew positional deviation. Even in a configuration that corrects only the positional deviation in the width direction, when the paper is skewed, the timing at which the leading edge of the paper reaches the downstream edge detection sensor differs by correcting the positional deviation in the width direction. Therefore, the timing of transportation to the target value also fluctuates.

Further, in the above-described embodiment, the sheet conveying speed is adjusted by changing the conveying rotational speed of the nipping roller pair 31. However, the conveying rotational speed of the nipping roller pair 31 is not changeable. In addition, a transport roller pair for adjusting the transport speed of the paper may be separately provided downstream of the nipping roller pair 31 .

In addition, in the above-described embodiments, the case where the conveying apparatus according to the present invention is applied to an ink jet image forming apparatus is taken as an example, but the conveying apparatus of the present invention can also be applied to an electrophotographic image forming apparatus. be.

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

24, reference numeral 300 denotes an electrophotographic image forming apparatus; 302, a document reading unit for optically reading image information of a document D; 303, exposure light L based on the image information read by the document reading unit 302; 305, an exposure unit that irradiates onto the surface of the photosensitive drum 305; 304, a developing unit that forms a toner image (image) on the photosensitive drum 305; 310, a document conveying unit for conveying the set document D to the document reading unit 302; A fixing device 330 for fixing an image is a transport device for transporting the paper P fed from the paper feed units 312 to 314 to the transfer unit 307 .

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

24. When the document D is conveyed by the document conveying unit 310 in the direction of the arrow in FIG. is irradiated with the exposure light L, and an electrostatic latent image is formed 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). Also, the paper P fed from any one of the paper feeding units 312 to 314 is conveyed to the transfer unit 307 by the conveying device 330, and the toner image formed on the photoreceptor 305 is transferred onto the paper P. FIG. After that, the paper P is transported to the fixing device 320, and after the toner image is fixed, the paper P is discharged outside the device.

In such an electrophotographic image forming apparatus 300, it is necessary to adjust the conveying speed of the paper P so that the paper P and the toner image on the photosensitive member 305 reach the transfer section 307 in time. Therefore, by applying a transport device similar to that of the above-described embodiment as the transport device 330 that transports the paper P to the transfer unit 307, the positional deviation of the paper P is corrected and the transport timing is controlled with high accuracy. P can be transported to the transfer unit 307 .

Further, the conveying device according to the present invention can also be applied to a post-processing device that performs staple processing, folding processing, and the like on the paper after the image has been transferred to the paper.

FIG. 25 shows an example in which the conveying 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 stapling device 420 for binding sheets, a folding device 430 for center-folding sheets, and a plurality of trays ( stacking units 441 , 442 , 443 , and a conveying device 450 for conveying sheets conveyed from the image forming apparatus 100 to the punching device 410 . Further, the post-processing device 400 conveys the sheet conveyed from the image forming apparatus 100 to one of the three conveying routes J1 to J3, and performs different post-processing.

The first transport path J<b>1 is a path for transporting a sheet that has been punched by the punching device 410 or a sheet that has not been punched to the first tray 441 . The second transport path J2 is a path for transporting the sheets to the stapling device 420 and transporting the bound sheets to the second tray 442 . The third transport path J3 is a path for transporting the sheet to the folding device 430 and transporting the center-folded sheet to the third tray 443 .

By applying the same transport device as in the above-described embodiment as the transport device 450 provided in the post-processing device 400, it is possible to correct the misalignment of the paper and transport it at a predetermined timing with high accuracy. Therefore, it is possible to improve the accuracy of subsequent punching, binding, or center-folding.

Further, the conveying device according to the present invention is not limited to a conveying device that conveys paper. The conveying device according to the present invention can handle paper (including plain paper, thick paper, thin paper, coated paper, label paper, envelopes, etc.), other recording media on which images are printed, such as OHP sheets and OHP films, or documents. The present invention can also be applied to a conveying device that conveys sheets such as the above. Furthermore, the conveying device according to the present invention is applicable not only to a sheet such as a recording medium or an original, but also to a conveying device that conveys a medium to be conveyed other than a sheet such as an electronic substrate.

7 conveying device 11 transfer drum (conveying rotating body)
16 gripper (grasping part)
17 rotary encoder (rotation speed detection means)
18 Laser Doppler Velocimeter (Transported Medium Velocity Detection Means)
23 conveying speed control unit 31 nipping roller pair (position changing means)
57 rotary encoder (driving position detection means)
58 Rotary encoder (driving position detection means)
101 first CIS (position detection means)
102 Second CIS (position detection means)
103 Third CIS (position detection means)
P paper (transported medium)
Pa side end

JP-A-2005-53646

Claims (22)

position detection means for detecting the position of the side edge of the medium to be transported;
In at least one of the width direction of the transported medium and the rotational direction within the transport surface of the transported medium, while transporting the transported medium, according to the position of the transported medium detected by the position detection means. position changing means for driving to change the position of the transported medium a plurality of times;
A conveying device comprising
The transport speed control unit changes the transport speed of the medium to be transported each time the position of the medium to be transported changes by the position changing means , and changes the transport speed of the medium to be transported a plurality of times. transport device. 2. The conveying apparatus according to claim 1, wherein the position detection means can detect the position of the side edge of the medium to be conveyed a plurality of times. 2. The conveying apparatus according to claim 1, wherein the position changing means is a pair of rollers that nip and convey the medium to be conveyed . a plurality of position detection means capable of detecting the positions of the side edges of the medium to be conveyed;
In at least one of the width direction of the transported medium and the rotational direction within the transport surface of the transported medium, while transporting the transported medium, according to the position of the transported medium detected by the position detection means. position changing means for driving to change the position of the medium to be transported;
A conveying device comprising
The conveying speed control unit changes the conveying speed of the medium to be conveyed by the position changing means each time the position of the medium to be conveyed changes, and changes the conveying speed of the medium to be conveyed a plurality of times. Conveyor. 5. The conveying apparatus according to claim 4, wherein the positions of the side edges of the medium to be conveyed can be detected multiple times by the plurality of position detecting means. 5. The conveying apparatus according to claim 4, wherein the plurality of position detecting means are arranged upstream and downstream of the position changing means in the conveying direction of the medium to be conveyed. 5. The conveying apparatus according to claim 4, wherein the position changing means is a pair of rollers that pinch and convey the medium to be conveyed . driving position detecting means for detecting a driving position when the position changing means is driven in at least one of the width direction of the medium to be transported and the rotational direction within the transporting surface of the medium to be transported;
8. The conveying apparatus according to any one of claims 1 to 7, wherein the conveying speed of the medium to be conveyed is changed based on the detection result of the driving position detecting means. a conveying rotating body having a gripping portion for gripping the medium to be conveyed provided on an outer peripheral surface thereof, arranged downstream of the position changing means in the conveying direction;
By changing the transport speed of the medium to be transported based on the amount of change in the position of the medium to be transported, the medium to be transported is transported to the transport rotator in accordance with the timing at which the gripping section grips the medium to be transported. The conveying device according to any one of claims 1 to 8 . A rotational speed detecting means for detecting the conveying rotational speed of the conveying rotator;
10. The conveying apparatus according to claim 9, wherein the conveying speed of the medium to be conveyed is changed based on the amount of change in the position of the medium to be conveyed and the detection result of the rotational speed detecting means. transported medium speed detection means for directly detecting the transport speed of the transported medium;
The conveying apparatus according to any one of claims 1 to 10, wherein the conveying speed of the medium to be conveyed is changed based on the amount of change in the position of the medium to be conveyed and the detection result of the medium to be conveyed speed detection means. . The number of times the position of the medium to be transported is changed by the position changing means and the number of times the transport speed is changed by the transport speed control section are smaller than the number of position detections by the position detection means. 1. The conveying device according to item 1 . An image forming apparatus comprising the conveying device according to any one of claims 1 to 12 . While transporting the medium to be transported, the medium to be transported is moved in at least one of the width direction and the rotational direction within the transport surface of the medium to be transported according to the detected position of the side edge of the medium to be transported. A conveying method for changing the position of the medium to be conveyed a plurality of times,
moving the medium to be conveyed in at least one of the width direction and the rotational direction within the surface of the medium to be conveyed to change the conveying speed of the medium to be conveyed each time the position of the medium to be conveyed changes; A conveying method characterized by changing the conveying speed of a medium to be conveyed a plurality of times . While conveying the medium to be conveyed, the medium to be conveyed is moved in at least one of the width direction and the rotational direction within the conveying surface of the medium to be conveyed according to the position of the side end portion of the medium to be conveyed that is detected multiple times. 15. The transportation method according to claim 14, wherein the substrate is moved to . The position of the medium to be conveyed is changed by moving the medium to be conveyed in at least one of the width direction and the rotational direction within the medium to be conveyed conveying surface while nipping and conveying the medium to be conveyed by the pair of rollers. 15. The conveying method according to claim 14, wherein the change is made a plurality of times . detecting the drive position of the roller pair when the medium to be transported is moved in at least one of the width direction and the rotational direction within the medium transport plane;
The conveying method according to claim 16, wherein the conveying speed of the medium to be conveyed is changed based on the detected drive position of the roller pair. A conveying method for grasping and conveying the medium conveyed by the pair of rollers by the grasping portion of a conveying rotator having a grasping portion provided on an outer peripheral surface thereof, the conveying method comprising:
By changing the transport speed of the medium to be transported according to the position of the medium to be transported after the change, the medium to be transported is moved to the rotating body in accordance with the timing at which the gripping section grips the medium to be transported. 18. The transportation method according to claim 16 or 17, wherein the substrate is transported to . 19. The transporting method according to claim 18, wherein the transport speed of the transported medium is changed based on the position change amount of the transported medium and the transport rotation speed of the transport rotating body. 20. The conveying speed of the medium to be conveyed according to any one of claims 14 to 19, wherein the conveying speed of the medium to be conveyed is changed based on a position change amount of the medium to be conveyed and a detection result obtained by directly detecting the conveying speed of the medium to be conveyed. transportation method. 21. The method according to any one of claims 14 to 20, wherein the number of times the position of the medium to be transported is changed and the number of times the transport speed of the medium to be transported is changed are less than the number of times the position of the side edge of the medium to be transported is detected. The conveying method according to any one of the items . An image forming method, comprising: transporting a medium to be transported by the transporting method according to any one of claims 14 to 21, and forming an image on the medium to be transported.

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