JP7182061B2 - 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. 23, 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 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 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, if the conveying speed (rotational speed) of the conveying roller pair is controlled while conveying the sheet, as in the conveying device described in Japanese Patent Application Laid-Open No. 2002-200012, there is a possibility that slippage may occur between the conveying roller pair and the sheet. . When such slippage occurs, the timing at which the sheet reaches the target position is shifted, and the sheet cannot be conveyed with high accuracy.

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. while transporting the transported medium in at least one of the width direction of the transported medium and the rotational direction in the transported medium transport surface to change the position of the transported medium; a conveying rotator disposed on the downstream side in the conveying direction of the conveying rotator provided with a receiving portion for receiving the medium to be conveyed, wherein the position of the medium to be conveyed is changed by the position changing means; and a rotation speed control unit for changing the rotation speed of the conveying rotor.

According to the present invention, even if the transport timing of the medium to be transported changes with the change in the position of the medium to be transported by the position changing means, the rotational speed of the transport rotating body can be changed according to the changed position of the medium to be transported. By changing , it is possible to cause the receiving section to reach a desired position in accordance with the transport timing of the medium to be transported. As a result, the medium to be transported can be received with high precision (with good timing) by the receiving section.

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 a conveyance operation. It is a figure which shows the flowchart of rotation speed control. FIG. 10 is a diagram for explaining a method of calculating a positional change amount of a sheet accompanying positional deviation correction; FIG. 5 is a diagram showing an example in which an upstream transfer cylinder, a paper carrying drum, and a downstream transfer cylinder are interlocked. 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|movement which concerns on other embodiment. It is a block diagram which shows the control system of the conveying apparatus which concerns on another embodiment. FIG. 11 is a diagram showing a flow chart of a transport operation according to still another embodiment; 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 for separating and feeding the papers P one by one from the paper feeding tray 5, and a and a conveying device 7 for conveying the sheet P that has been picked up. 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 unit]
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 transfer drum 8 on the upstream side, the paper carrying drum 9, and the transfer drum 11 on the downstream side also serve as a part of the transport device 7 for transporting the paper P.

The paper P conveyed from the paper feeding unit 1 to the image forming unit 2 is gripped at its leading end by a swingable gripper 16 as a receiving unit provided on the surface of the transfer cylinder 8, and is moved by the movement of the surface of the transfer cylinder 8. 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 . 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.

A similar gripper is provided as a receiving portion on the surface of the paper carrying drum 9, and the leading edge 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 part]
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 part]
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.

The transfer drum 8, which is a component of the transfer device 7, has a transfer drum driving motor 81 as a transfer rotating body driving means for rotating the transfer drum 8, and a rotation speed detection means for detecting the rotation speed of the transfer drum 8. A rotary encoder 82 is provided. The rotation speed of the transfer drum 8 is controlled based on the detection result of this rotary encoder 82 .

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 pair of nipping rollers 31 in the width direction of the sheet, and a rotation mechanism for rotating the holding frame 72 and the pair of nipping rollers 31 in the sheet conveying plane. and an oblique direction drive mechanism 39 for rotating in the direction.

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. Accordingly, the action roller 49 provided on the lever member 50 pushes the projection 72a of the holding frame 72 against the biasing force of the tension spring 60, so that the holding frame 72 rotates in the paper conveying plane. Rotate (counterclockwise in FIG. 4).

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.

The conveying apparatus according to this embodiment includes a control unit 20 that controls the operations of the pair of nipping rollers 31 and the transfer drum 8 arranged on the downstream side in the conveying direction. The control unit 20 controls the displacement correction operation of the nipping roller pair 31 , that is, the amount of movement of the nipping roller pair 31 in the width direction, the amount of rotation in the sheet conveying plane, and the rotational speed of the transfer drum 8 .

As shown in FIG. 6, the control unit 20 includes a positional deviation amount calculation unit 21 for calculating the positional deviation amount of the paper, a target reception timing calculation unit 24 for calculating the target reception timing for the transfer cylinder 8 to receive the paper, and a transfer and a rotational speed control unit 25 for controlling the conveying rotational speed of the cylinder 8 .

The misregistration amount calculator 21 is configured to calculate the misregistration amount of the paper based on the detection results of the CISs 101-103. The control unit 20 controls the nipping roller pair 31 based on the amount of misalignment of the sheet calculated by the misalignment amount calculation unit 21 . That is, in order to correct the misalignment of the paper, the control unit 20 controls the width direction drive motor 62 for driving the pair of nipping rollers in the width direction, and the oblique driving motor 62 for rotating the pair of nipping rollers in the rotational direction within the paper transport plane. Each row direction drive motor 63 is controlled.

The target receiving timing calculation unit 24 calculates the paper transport position information detected by the downstream edge detection sensor 200 and the rotation of the transfer drum 8 detected by the home position sensor 80 (see FIG. 1) provided on the transfer drum 8. Based on the positional information, a target reception timing for the transfer cylinder 8 to receive the paper is calculated. As described above, in the present embodiment, the paper P is transferred to the transfer cylinder 8 by gripping the paper P with the gripper 16 provided on the transfer cylinder 8 . At this time, in order to reliably transfer the paper P to the gripper 16, the gripper 16 similarly moves the paper P to the paper receiving position A in accordance with the timing when 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 sheet P reaches the sheet receiving position A is set as the target receiving timing. The timing at which the gripper 16 reaches the paper gripping position A is determined by detecting the rotation reference position C of the transfer drum 8 by the home position sensor 80 .

The rotation speed control unit 25 rotates the transfer cylinder 8 based on detection information from a rotary encoder 82 (see FIG. 2) that detects the rotation speed of the transfer cylinder 8 and the amount of change in the position of the paper caused by positional deviation correction. Control speed. Here, the amount of change in the position of the paper when correcting the positional deviation is the amount of movement in the width direction and the amount of rotation in the direction of rotation within the paper transport plane when the nipping roller pair 31 corrects the positional deviation of the paper. Equivalent to. Therefore, in the present embodiment, the rotation speed control unit 25 receives the detection signals of 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, whereby the sheet is positional change amount is obtained indirectly.

Further, the rotation speed control section 25 controls the rotation speed of the transfer drum 8 based on the target reception timing calculated by the target reception timing calculation section 24 or the target reception timing corrected thereafter.

Next, a method for calculating the amount of sheet misalignment 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 arrow S1 in FIG. 10), Rotate in the direction of rotation in the paper 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).

After that, the leading edge Pb of the paper P is detected by the upstream leading edge detection sensor 220, and based on the detection timing, the pair of nipping rollers 31 come into contact with each other and start to rotate, as shown in FIGS. 11A and 11B. As shown, the paper 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 information of the downstream edge detection sensor 200 and the detection information of the home position sensor 80 of the transfer cylinder 8, the target reception timing of the paper at the paper reception position A of the transfer cylinder 8 is determined by the target reception timing calculator. 24 (see FIG. 6) and 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. In the flowchart shown in FIG. 15, the return operation (first correction) S5 is displayed in order after the detection S3 of the downstream-side leading edge detection sensor 200, but the return operation S5 is performed downstream immediately after the pick-up operation S2. It may be started before detection S<b>3 by the side tip detection sensor 200 .

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). In addition to moving the sheet P, it is rotated in the direction of rotation (in the direction of arrow W3 or W4 in FIG. 13) to correct the positional deviation of the sheet P (see FIG. 15). S7).

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 as described above is performed after setting the target receiving timing, the position of the paper in the transport direction will change accordingly. The timing of 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 do not match, and the gripper 16 may not be able to grip the paper accurately. As a solution to this problem, a method of adjusting the transport speed of the paper in accordance with the timing at which the gripper 16 reaches the paper receiving position A by changing the transport rotation speed of the nipping roller pair 31 that transports the paper is conceivable. be done. However, in this method, there is a possibility that slippage occurs between the nipping roller pair 31 and the paper when the conveying rotation speed of the nipping roller pair 31 is changed, and the timing of conveying the paper cannot be corrected with high accuracy. There is

Therefore, in the present embodiment, when misregistration correction (second correction) is performed after the target reception timing is set (every time misregistration correction is performed), the receiving side's The rotation speed of the transfer drum 8 is changed (corrected) (S8 in FIG. 15). On the other hand, the nipping roller pair 31 is controlled to rotate at a preset predetermined (constant) conveying rotation speed based on detection information from a rotary encoder 96 (see FIG. 3) provided in the nipping roller pair 31. It is

By changing the rotation speed of the transfer cylinder 8 based on the correction amount of the positional deviation of the paper, the timing at which the paper P reaches the paper receiving position A is changed as shown in FIGS. At the same time, 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 . Then, when the paper P reaches the paper receiving position A, the nipping roller pair 31 is separated from each other, and the transportation of the paper by the nipping roller pair 31 is completed. If the positional deviation correction is not performed after the target receiving timing is set, the arrival timing of the paper at the paper receiving position A basically does not change. No changes are made.

A method of controlling the rotation speed of the transfer drum 8 will be described below with reference to the flow chart of FIG.

As shown in FIG. 16, when the rotation speed control of the transfer drum 8 is started, the gripper 16 is first rotated based on the detection information of the home position sensor 80 of the transfer drum 8 before the target receiving timing is set. is at the rotation reference position C (S11 in FIG. 16). Then, as described above, the downstream leading edge detection sensor 200 detects the leading edge of the paper (S12 in FIG. 16), and the target receiving timing is set 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 rotation speed of the transfer drum 8 is calculated in accordance with the set target receiving timing (S14 in FIG. 16). The calculation of the target rotation speed of the transfer drum 8 may be performed by the target receiving timing calculation section 24 or may be performed by another calculation section. Then, the rotation speed of the transfer drum 8 is controlled based on the calculated target rotation speed (S15 in FIG. 16). In this embodiment, the rotation speed of the transfer drum 8 is managed based on a signal from a rotary encoder 82 provided on the transfer drum 8 . Therefore, in order to determine whether the rotation speed of the transfer drum 8 is faster or slower than the target rotation speed, the rotation speed control section 25 acquires a signal from the rotary encoder 82 (S16 in FIG. 16).

Further, when positional deviation correction is performed by the nipping roller pair 31 after setting the target receiving timing, the rotation speed of the transfer cylinder 8 is changed based on the amount of positional deviation correction of the paper associated with the positional deviation correction. 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 this embodiment, the rotation speed control unit 25 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). Then, the target rotational speed of the transfer drum 8 is calculated based on the target receiving timing and the signals from the respective rotary encoders 82, 57 and 58 (S14 in FIG. 16). Then, the rotation speed of the transfer drum 8 is controlled based on the newly calculated target rotation speed (S15 in FIG. 16). Then, such control of the rotation speed of the transfer drum 8 is performed until the sheet conveying time reaches the target receiving timing (S18 in FIG. 16). When the paper transport time reaches the target receiving timing, the gripper 16 reaches the paper receiving position A in time with the paper (S19 in FIG. 16). As a result, the gripper 16 can reliably grip the paper with good timing.

A method of calculating the amount of change in the position of the paper associated with positional deviation correction will be described below 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..Equation 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 3
Yp=sin(θ')Fp Expression 4

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). Based on the position change amount G thus calculated, the time required for the paper to reach the paper receiving position A (target receiving timing) is calculated, and the rotational speed of the transfer cylinder 8 is adjusted based on the calculated time. By adjusting, the paper can be transferred to the transfer cylinder 8 (gripper 16) at a predetermined timing.

G=Qx-Vx Expression 5

As described above, according to the conveying apparatus according to the present embodiment, even if the position of the sheet in the conveying direction changes due to positional deviation correction, the positional deviation correction amount (width By changing (correcting) the rotational speed of the transfer drum 8 based on the direction and the amount of change in the position of the paper in the direction of rotation within the paper conveying plane, the gripper is operated in accordance with the timing at which the paper reaches the paper receiving position A. 16 can reach the paper receiving position A. Further, by correcting the rotation speed of the transfer drum 8 on the receiving side instead of the conveying speed of the pair of nipping rollers 31 on the feeding side, slippage between the pair of nipping rollers 31 and the paper can be avoided. The paper can be transferred to the transfer cylinder 8 with high accuracy. As a result, misalignment of the image with respect to the paper 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, the positional deviation correction and the rotational speed of the transfer drum 8 are changed each time the position of the paper is detected. Positional deviation correction may be performed based on the detection result of (1), and the rotation speed of the transfer drum 8 may be changed according to the positional deviation correction. That is, the number of times the positional deviation correction is performed and the number of times the rotation speed of the transfer drum 8 is changed may be less than the number of times the position of the paper is detected.

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

Further, in the present embodiment, the downstream edge detection sensor 200 is configured to be driven together (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 detection by the downstream leading edge detection sensor 200 (after setting the target receiving timing), if the positional deviation of the sheet is corrected by the return operation of the nipping roller pair 31 (first correction), the operation amount of the return operation is reduced. The target receiving timing fluctuates according to the size (the amount of skew of the paper). Therefore, in this case, in order to eliminate the influence of the positional deviation correction operation (first correction) on the target receiving timing, the rotation speed of the transfer drum 8 is changed according to the return operation (first correction), or Alternatively, it is necessary to detect the sheet transport timing by the downstream edge detection sensor 200 after the return operation is completed.

On the other hand, 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 possible to perform detection while facing each time (in the same posture each time). In this way, the leading edge detection position by the downstream leading edge detection sensor 200 does not change according to the degree of skew of the sheet, so the target receiving 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) every time the nipping roller pair 31 is returned, the distance from the downstream edge detection sensor 200 to the sheet receiving position A is the same each time. Become. Therefore, the change in the distance from the downstream edge detection sensor 200 to the sheet receiving position A does not affect the target receiving timing.

As described above, in this embodiment, the downstream edge detection sensor 200 is driven together with the nipping roller pair 31, so that various influences when the sensor is fixed can be avoided. It is not necessary to change the rotation speed of the transfer drum 8 according to the return operation (first correction). Therefore, it is only necessary to change the rotation speed of the transfer drum 8 in response to the positional deviation correction (second correction) after the return operation. Further, since the positional deviation correction after the return operation (second correction) is a fine positional deviation correction performed after the positional deviation is once corrected, the rotation speed of the transfer drum 8 usually changes only slightly during this correction operation. Therefore, even when the paper is conveyed at high speed or when the conveying distance to the paper receiving position A is short, it is possible to sufficiently cope with the situation.

In addition, since the target receiving timing is not affected by the returning operation, the conveying timing can be detected by the downstream leading edge detection sensor 200 before the returning operation is completed (before the returning operation is started or during the returning operation). become. Therefore, the target receiving timing can be set at an early stage, and a sufficient control time for the rotation speed of the transfer drum 8 can be ensured, 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, 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 start of changing the rotation speed of the transfer cylinder 8 will be long. . On the other hand, in the case of indirectly calculating the positional deviation correction amount of the paper from the information from the rotary encoder, the load of communication and arithmetic processing is reduced, so the rotational speed of the transfer cylinder 8 can be changed at an early timing. can be started. Therefore, even in a configuration with a high transport speed or a configuration with a short transport distance to the paper receiving position A, it is possible to secure the control time for the rotation speed of the transfer drum 8 and receive the paper with high accuracy.

A conveying apparatus according to another embodiment of the present invention will be described with reference to FIGS. 19 and 20. FIG.

In the conveying apparatus according to the present embodiment, a rotary encoder 96 for detecting the conveying rotation speed of the nipping 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.

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

Therefore, in the present embodiment, the rotational speed of the transfer drum 8 is determined by the signal from the rotary encoder 82 that detects the rotational speed of the transfer drum 8, the amount of movement in the width direction of the pair of nipping rollers 31, and the amount of rotation in the sheet conveying plane. In addition to the signals from the respective rotary encoders 57 and 58 for detecting , the change is also made based on the signal from the rotary encoder 96 of the nipping roller pair 31 . As a result, even if the conveying rotation speed of the pair of nipping rollers 31 changes, the timing of the paper and the gripper 16 on the transfer drum 8 can be matched, and the paper can be conveyed with higher accuracy.

Figures 21 and 22 are block diagrams and flow charts of a transport apparatus according to yet another embodiment of the present invention.

In the embodiment shown in FIGS. 21 and 22, 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 embodiment shown in FIGS. 19 and 20, 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 this embodiment, instead of the rotary encoder 96 for detecting the conveying rotational speed of the nipping roller pair 31, the rotational speed of the transfer cylinder 8 is controlled based on the sheet conveying speed directly detected by the laser Doppler velocimeter 18. (S20 in FIG. 22). 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 transport timing due to the slippage and to transport the paper 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 it goes without saying that various modifications can be made without departing from the gist of the present invention.

In the flowcharts shown in FIGS. 16, 20, and 22, the signal from the home position sensor 80 is received in order to set the target transport timing. Alternatively, the signal from the rotary encoder 82 of the transfer drum 8 may be received. Since the position of the gripper 16 can be confirmed based on the signal from the rotary encoder 82 of the transfer drum 8 without receiving the signal from the home position sensor 80, it is possible to set the target transfer timing.

In the above-described embodiment, the receiving portion of the transfer cylinder 8 that receives the paper is the gripper 16 that swings to grip the paper. may

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 they can detect the side edges of the paper.

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 transport timing to the target position also fluctuates.

Further, in the above-described embodiment, as an embodiment of the conveying apparatus according to the present invention, the conveying apparatus mounted in the image forming apparatus has been described as an example, but the conveying apparatus according to the present invention is limited to the conveying apparatus for conveying sheets. do not have. The conveying device according to the present invention can also be applied to a conveying device that conveys a medium to be conveyed such as an electronic substrate.

7 transport device 8 transfer drum (transport rotating body)
16 gripper (receiving part)
17 rotary encoder (rotation speed detection means)
18 Laser Doppler Velocimeter (Transported Medium Velocity Detection Means)
25 rotation speed control unit 31 pinching 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 (14)

position detection means for detecting the position of the side edge 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 rotator disposed on the downstream side of the position changing means in the conveying direction and provided with a receiving portion for receiving the medium to be conveyed;
A conveying device comprising
A conveying apparatus, comprising: a rotational speed control section that changes the rotational speed of the conveying rotating body according to the position of the medium to be conveyed after being changed by the position changing means. 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;
2. A conveying apparatus according to claim 1, wherein the rotation speed of said conveying rotor is changed based on the detection result of said driving position detecting means. A rotation speed detection means for detecting the rotation speed of the conveying rotating body,
3. The conveying apparatus according to claim 1, wherein the rotational speed of the conveying rotating body 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;
4. The conveying apparatus according to any one of claims 1 to 3, wherein the rotation speed of the conveying rotating body is changed based on the amount of change in the position of the conveyed medium and the detection result of the conveyed medium speed detection means. . The position detection means detects the position of the side edge of the medium to be conveyed a plurality of times,
The position changing means changes the position of the medium to be transported a plurality of times according to the position of the medium to be transported detected by the position detecting means,
5. The rotation speed control unit according to any one of claims 1 to 4, wherein the rotation speed of the conveying rotor is changed a plurality of times according to the position of the medium to be conveyed after being changed by the position changing unit. Conveyor. 2. 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 rotational speed of the conveying rotating body is changed by the rotational speed control part are smaller than the number of times of position detection by the position detection means. 6. The conveying device according to any one of 5 to 5. An image forming apparatus comprising the conveying device according to claim 1 . 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 by causing the medium to be conveyed to change the position of the medium to be conveyed, and then receiving and conveying the medium to be conveyed by a conveying rotating body,
The rotational speed of the conveying rotating body is adjusted according to the changed position of the medium to be conveyed when 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. A conveying method characterized by changing. While transporting the medium to be transported by the position changing means, the position changing means is driven in at least one of the width direction of the medium to be transported and the rotational direction in the transport plane of the medium to be transported, thereby changing the medium to be transported. change position,
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 in the transporting surface of the medium to be transported;
9. The transport method according to claim 8, wherein the rotation speed of the transport rotor is changed based on the detected driving position of the position changing means. 10. The transport method according to claim 8, wherein the rotation speed of the transport rotor is changed based on the amount of change in the position of the medium to be transported and the rotation speed of the transport rotor. 11. The rotational speed of the conveying rotor according to any one of claims 8 to 10, wherein the rotation speed of the conveying rotating body is changed based on the amount of change in the position 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. moving the medium to be conveyed in at least one of the width direction and the rotational direction in 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 a plurality of times; changing the position of the medium multiple times,
12. The transporting method according to any one of claims 8 to 11, wherein the rotation speed of the transport rotating body is changed a plurality of times according to the changed position of the medium to be transported. 13. The method according to any one of claims 8 to 12, wherein the number of times the position of the medium to be transported is changed and the number of times the rotation speed of the transport rotating body is changed are smaller 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 8 to 13, and forming an image on the medium to be transported.

Images