JP6988167B2 - Image forming device and transfer control method - Google Patents

Description

The present invention relates to an image forming apparatus and a transport control method.

In general, an image forming apparatus (printer, copier, facsimile, etc.) using electrophotographic process technology irradiates (exposes) a charged photoconductor drum (image carrier) with laser light based on image data. Form an electrostatic latent image. Then, the image forming apparatus visualizes the electrostatic latent image and forms the toner image by supplying toner from the developing unit to the photoconductor drum on which the electrostatic latent image is formed. Further, in the image forming apparatus, the toner image is temporarily or secondarily transferred to the paper, and the paper is heated and pressed by the fixing nip of the fixing portion to fix the toner image on the paper. Further, in the image forming apparatus, a resist roller for correcting the positional deviation in the width direction of the paper is provided on the upstream side of the transfer portion for transferring the image to the paper (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-133634

By the way, in the image forming apparatus, there is a problem that a phenomenon (secondary scanning bending) occurs in which the paper transport direction is bent in the sub-scanning direction due to the misalignment from the resist roller to the fixing nip through the secondary transfer nip. be. In addition to the above-mentioned misalignment, such sub-scanning bending is likely to occur when there is a difference in the diameters of both ends in the paper width direction (sub-scanning direction) of the roller due to durability or the like. Further, since long paper having a long size in the transport direction is easily affected by the above, sub-scanning bending occurs remarkably. Since such sub-scanning bending causes image defects due to misalignment and distortion of the image transferred by the transfer unit, there is a demand for a technique for suppressing sub-scanning bending.

On the other hand, in Patent Document 1, a line sensor is arranged between the resist roller and the transfer roller, and the line sensor is used for the widthwise end (side edge) of the paper while the paper is being conveyed by the transfer roller. A technique for resist swing control that detects a position and moves a resist roller based on the detection result is described.

However, in the technique described in Patent Document 1, the deviation from the reference position of the paper side edge is detected by the line sensor, the swing amount of the resist roller is determined from the detection result, and the resist roller is shaken by the determined value. Since the movement is controlled, the paper side edge may shift from the reference position when the swing is stopped.

An object of the present invention is to provide an image forming apparatus and a transport control method capable of more accurately correcting sub-scanning bends of paper.

The image forming apparatus according to the present invention is
A transfer unit that transfers images to paper,
A paper transport member provided on the upstream side of the transfer unit in the paper transport direction to transport the paper, and a paper transport member.
A control unit for controlling the swing of the paper transport member so as to swing the paper along the width direction of the paper is provided.
Wherein, the previous SL the first swing the first swing and the sheet transport members which end portion in the width direction swings the sheet transport members in a direction toward the target position of the sheet in the reverse direction Control is performed to alternately execute the first swing and the second swing by using a preset value predetermined for the paper as the execution timing for alternately performing the second swing to be shaken.
The preset value defines the amount of swing of the first swing and the second swing .
The image forming apparatus according to the present invention is
A transfer unit that transfers images to paper,
A paper transport member provided on the upstream side of the transfer unit in the paper transport direction to transport the paper, and a paper transport member.
A control unit for controlling the swing of the paper transport member so as to swing the paper along the width direction of the paper is provided.
The control unit swings the paper transport member in a direction in which the end portion in the width direction of the paper swings toward a target position, and swings the paper transport member in the direction opposite to the first swing. Using a preset value predetermined for the paper, the execution timing for alternately performing the second swing to be moved is controlled to alternately execute the first swing and the second swing.
The preset value includes a value indicating a swing speed in the first swing or the second swing.
The image forming apparatus according to the present invention is
A transfer unit that transfers images to paper,
A paper transport member provided on the upstream side of the transfer unit in the paper transport direction to transport the paper, and a paper transport member.
A control unit for controlling the swing of the paper transport member so as to swing the paper along the width direction of the paper is provided.
The control unit swings the paper transport member in a direction in which the end portion in the width direction of the paper swings toward a target position, and swings the paper transport member in the direction opposite to the first swing. Using a preset value predetermined for the paper, the execution timing for alternately performing the second swing to be moved is controlled to alternately execute the first swing and the second swing.
A table in which the preset values are defined according to the image forming conditions is provided.
The image forming apparatus according to the present invention is
A transfer unit that transfers images to paper,
A paper transport member provided on the upstream side of the transfer unit in the paper transport direction to transport the paper, and a paper transport member.
A control unit for controlling the swing of the paper transport member so as to swing the paper along the width direction of the paper is provided.
The control unit swings the paper transport member in a direction in which the end portion in the width direction of the paper swings toward a target position, and swings the paper transport member in the direction opposite to the first swing. The execution timing for alternately executing the second swing to be moved is controlled by alternately executing the first swing and the second swing by using a preset value predetermined for the paper. The execution timings of the first swing and the second swing are changed according to the image formation conditions.

The transport control method according to the present invention is
In an image forming apparatus including a transfer unit for transferring an image to paper and a paper transport member provided on the upstream side of the transfer unit in the paper transport direction to transport the paper, the paper is transferred in the width direction of the paper. It is a transport control method that controls the swing of the paper transport member so as to swing along the paper transport member.
The oscillating the width direction of the sheet transport member and the first oscillating end portion swings the sheet transport members in a direction towards the target position in a direction opposite to the first swing before SL paper 2 Control is performed to alternately execute the first swing and the second swing by using a preset value predetermined for the paper for the execution timing of alternately performing the swing.
The preset value defines the amount of swing of the first swing and the second swing .
The transport control method according to the present invention is
In an image forming apparatus including a transfer unit for transferring an image to paper and a paper transport member provided on the upstream side of the transfer unit in the paper transport direction to transport the paper, the paper is transferred in the width direction of the paper. It is a transport control method that controls the swing of the paper transport member so as to swing along the paper transport member.
The first swing that swings the paper transport member in the direction in which the end portion of the paper in the width direction toward the target position and the second swing that swings the paper transport member in the direction opposite to the first swing. Control is performed to alternately execute the first swing and the second swing by using a preset value predetermined for the paper for the execution timing of alternately performing the motion.
The preset value includes a value indicating a swing speed in the first swing or the second swing.
The transport control method according to the present invention is
In an image forming apparatus including a transfer unit for transferring an image to paper and a paper transport member provided on the upstream side of the transfer unit in the paper transport direction to transport the paper, the paper is transferred in the width direction of the paper. It is a transport control method that controls the swing of the paper transport member so as to swing along the paper transport member.
The first swing that swings the paper transport member in the direction in which the end portion of the paper in the width direction toward the target position and the second swing that swings the paper transport member in the direction opposite to the first swing. Control is performed to alternately execute the first swing and the second swing by using a preset value predetermined for the paper for the execution timing of alternately performing the motion.
A table in which the preset values are defined according to the image forming conditions is provided.
The transport control method according to the present invention is
In an image forming apparatus including a transfer unit for transferring an image to paper and a paper transport member provided on the upstream side of the transfer unit in the paper transport direction to transport the paper, the paper is transferred in the width direction of the paper. It is a transport control method that controls the swing of the paper transport member so as to swing along the paper transport member.
The first swing that swings the paper transport member in the direction in which the end portion of the paper in the width direction toward the target position and the second swing that swings the paper transport member in the direction opposite to the first swing. The execution timing for alternately executing the motion is controlled to alternately execute the first swing and the second swing by using a preset value predetermined for the paper, and the first swing and the first swing and the second swing are controlled. The execution timing of the second swing is changed according to the image formation conditions.

According to the present invention, the sub-scanning bend of the paper can be corrected more correctly.

It is a figure which shows schematic the whole structure of the image forming apparatus in this embodiment. The main part of the control system of the image forming apparatus in this embodiment is shown. It is a figure explaining the control of the conventional resist swing, FIG. 3A shows the state before the resist roller pair moved, and FIG. 3B shows the state after the resist roller pair moved. It is a timing chart which shows the operation example of a line sensor, FIG. 4A shows the case of the conventional resist swing, and FIG. 4B shows the case of the resist swing of this embodiment. It is a figure explaining the outline of the resist swing control of this embodiment in the case of transporting a long paper, FIG. 5A is the state before the resist roller pair moves, and FIG. 5B is after the resist roller pair moves. The states of are shown respectively. 6A is a diagram illustrating a swinging operation in the present embodiment, FIG. 6A is a state in which side edge detection of paper is possible, FIG. 6B is a swingable direction of a resist roller pair, and FIG. 6C is a first. FIG. 6D shows a case of swinging in a direction and a case of swinging in a second direction opposite to the first direction. It is a flowchart which shows an example of the transfer control about the resist swing in the image forming apparatus of this embodiment.

Hereinafter, the present embodiment will be described in detail with reference to the drawings. FIG. 1 is a diagram schematically showing an overall configuration of an image forming apparatus 1 according to the present embodiment. FIG. 2 shows the main part of the control system of the image forming apparatus 1 in the present embodiment.

The image forming apparatus 1 of the present embodiment uses long paper or non-long paper as the paper S, and forms an image on the paper S.

In the present embodiment, the long paper is a sheet of paper having a length in the transport direction longer than the commonly used A4 size, A3 size and the like papers. Hereinafter, the term "paper" may include both long paper and non-long paper.

The image forming apparatus 1 is an intermediate transfer type color image forming apparatus using an electrophotographic process technique. That is, the image forming apparatus 1 primary transfers the Y (yellow), M (magenta), C (cyan), and K (black) color toner images formed on the photoconductor drum 413 to the intermediate transfer belt 421. After superimposing the toner images of four colors on the intermediate transfer belt 421, the toner image is formed by secondary transfer to paper.

Further, in the image forming apparatus 1, the photoconductor drums 413 corresponding to the four colors of YMCK are arranged in series in the traveling direction of the intermediate transfer belt 421, and the toner images of each color are sequentially transferred to the intermediate transfer belt 421 in one procedure. The tandem method is adopted.

As shown in FIG. 2, the image forming apparatus 1 includes an image reading unit 10, an operation display unit 20, an image processing unit 30, an image forming unit 40, a paper transport unit 50, a fixing unit 60, a control unit 100, and the like.

The control unit 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and the like. The CPU 101 reads a program according to the processing content from the ROM 102, develops it in the RAM 103, and centrally controls the operation of each block of the image forming apparatus 1 in cooperation with the expanded program. At this time, various data stored in the storage unit 72 are referred to. The storage unit 72 is composed of, for example, a non-volatile semiconductor memory (so-called flash memory) or a hard disk drive.

The control unit 100 transmits / receives various data to / from an external device (for example, a personal computer) connected to a communication network such as a LAN (Local Area Network) or WAN (Wide Area Network) via the communication unit 71. conduct. The control unit 100 receives, for example, image data transmitted from an external device, and forms a toner image on paper based on the image data (input image data). The communication unit 71 is composed of a communication control card such as a LAN card.

The image reading unit 10 includes an automatic document feeding device 11 called an ADF (Auto Document Feeder), a document image scanning device 12 (scanner), and the like.

The automatic document feeding device 11 conveys the document D placed on the document tray by the conveying mechanism and sends it out to the document image scanning device 12. The automatic document feeding device 11 can continuously read a large number of images (including both sides) of the original D placed on the original tray at once.

The document image scanning device 12 optically scans the document conveyed on the contact glass from the automatic document feeding device 11 or the document placed on the contact glass, and the reflected light from the document is a CCD (Charge Coupled Device). ) An image is formed on the light receiving surface of the sensor 12a, and the original image is read. The image reading unit 10 generates input image data based on the reading result of the original image scanning device 12. Predetermined image processing is performed on the input image data by the image processing unit 30.

The operation display unit 20 is composed of, for example, a liquid crystal display (LCD: Liquid Crystal Display) with a touch panel, and functions as a display unit 21 and an operation unit 22. The display unit 21 displays various operation screens, an image status display, an operation status of each function, and the like according to a display control signal input from the control unit 100. The operation unit 22 includes various operation keys such as a numeric keypad and a start key, receives various input operations by the user, and outputs an operation signal to the control unit 100.

The image processing unit 30 includes a circuit or the like that performs digital image processing according to initial settings or user settings for input image data. For example, the image processing unit 30 performs gradation correction based on the gradation correction data (gradation correction table LUT) in the storage unit 72 under the control of the control unit 100. Further, the image processing unit 30 performs various correction processes such as color correction and shading correction, compression processing, and the like, in addition to gradation correction, on the input image data. The image forming unit 40 is controlled based on the image data subjected to these processes.

The image forming unit 40 is an image forming unit 41Y, 41M, 41C, 41K, and an intermediate transfer unit 42 for forming an image with each colored toner of Y component, M component, C component, and K component based on the input image data. Etc. are provided.

The image forming units 41Y, 41M, 41C, 41K for the Y component, the M component, the C component, and the K component have the same configuration. For convenience of illustration and description, common components are indicated by the same reference numerals, and when distinguishing between them, the reference numerals are given with Y, M, C, or K. In FIG. 1, reference numerals are given only to the components of the image forming unit 41Y for the Y component, and the reference numerals are omitted for the other components of the image forming units 41M, 41C, and 41K.

The image forming unit 41 includes an exposure device 411, a developing device 412, a photoconductor drum 413, a charging device 414, a drum cleaning device 415, and the like.

The photoconductor drum 413 has, for example, an undercoat layer (UCL: Under Coat Layer), a charge generation layer (CGL: Charge Generation Layer), and a charge transport layer (CGL) on the peripheral surface of a conductive cylindrical body (aluminum raw tube) made of aluminum. It is a negatively charged organic photo-conductor (OPC) in which CTL: Charge Transport Layer) is sequentially laminated. The charge generation layer is made of an organic semiconductor in which a charge generation material (for example, a phthalocyanine pigment) is dispersed in a resin binder (for example, polycarbonate), and a pair of positive charges and negative charges are generated by exposure by an exposure apparatus 411. The charge transport layer is composed of a hole transporting material (electron donating nitrogen-containing compound) dispersed in a resin binder (for example, a polycarbonate resin), and transports positive charges generated in the charge generation layer to the surface of the charge transport layer. do.

The control unit 100 rotates the photoconductor drum 413 at a constant peripheral speed (linear speed) by controlling the drive current supplied to the drive motor (not shown) that rotates the photoconductor drum 413.

The charging device 414 uniformly charges the surface of the photoconductor drum 413 having photoconductivity to a negative electrode property. The exposure apparatus 411 is composed of, for example, a semiconductor laser, and irradiates the photoconductor drum 413 with a laser beam corresponding to an image of each color component. As a result, an electrostatic latent image of each color component is formed on the surface of the photoconductor drum 413 due to the potential difference from the surroundings.

The developing device 412 is, for example, a developing device of a two-component developing method, and forms a toner image by visualizing an electrostatic latent image by adhering toner of each color component to the surface of the photoconductor drum 413.

The drum cleaning device 415 has a cleaning member or the like that is slidably contacted with the surface of the photoconductor drum 413. The drum cleaning device 415 removes the transfer residual toner remaining on the surface of the photoconductor drum 413 after the primary transfer by the cleaning blade.

The intermediate transfer unit 42 includes an intermediate transfer belt 421, a primary transfer roller 422, a plurality of support rollers 423, a secondary transfer roller 424, a belt cleaning device 426, and the like.

The intermediate transfer belt 421 is composed of an endless belt and is stretched in a loop on a plurality of support rollers 423. At least one of the plurality of support rollers 423 is composed of a driving roller, and the other is composed of a driven roller. For example, it is preferable that the roller 423A arranged on the downstream side in the belt traveling direction with respect to the primary transfer roller 422 for the K component is the drive roller. This makes it easier to keep the running speed of the belt in the primary transfer unit constant. As the drive roller 423A rotates, the intermediate transfer belt 421 travels at a constant speed in the direction of arrow A.

The primary transfer roller 422 is arranged on the inner peripheral surface side of the intermediate transfer belt 421 so as to face the photoconductor drum 413 of each color component. The primary transfer roller 422 is pressed against the photoconductor drum 413 with the intermediate transfer belt 421 interposed therebetween, thereby forming a primary transfer nip for transferring the toner image from the photoconductor drum 413 to the intermediate transfer belt 421.

The secondary transfer roller 424 is arranged on the outer peripheral surface side of the intermediate transfer belt 421 so as to face the backup roller 423B arranged on the downstream side in the belt traveling direction of the drive roller 423A. The secondary transfer roller 424 is pressed against the backup roller 423B with the intermediate transfer belt 421 interposed therebetween, thereby forming a secondary transfer nip for transferring the toner image from the intermediate transfer belt 421 to the paper S.

The secondary transfer nip formed by the intermediate transfer belt 421, the backup roller 423B and the secondary transfer roller 424 corresponds to the "transfer portion" of the present invention.

When the intermediate transfer belt 421 passes through the primary transfer nip, the toner image on the photoconductor drum 413 is sequentially superimposed on the intermediate transfer belt 421 and the primary transfer is performed. Specifically, by applying a primary transfer bias to the primary transfer roller 422 and applying a charge having the opposite polarity to the toner on the side in contact with the primary transfer roller 422 of the intermediate transfer belt 421, the toner image is obtained by the intermediate transfer belt 421. Is electrostatically transferred to.

After that, when the paper passes through the secondary transfer nip, the toner image on the intermediate transfer belt 421 is secondarily transferred to the paper. Specifically, by applying a secondary transfer bias to the secondary transfer roller 424 and applying a charge having the opposite polarity to the toner on the side of the paper in contact with the secondary transfer roller 424, the toner image is electrostatically charged on the paper. Is transcribed. The paper on which the toner image is transferred is conveyed toward the fixing unit 60.

The belt cleaning device 426 has a belt cleaning blade or the like that is in sliding contact with the surface of the intermediate transfer belt 421, and removes the transfer residual toner remaining on the surface of the intermediate transfer belt 421 after the secondary transfer.

The fixing portion 60 includes an upper fixing portion 60A having a fixing surface side member arranged on the fixing surface side of the paper, and a lower fixing portion 60B having a back surface side support member arranged on the opposite surface side of the fixing surface of the paper. And a heating source 60C and the like. By pressing the back surface side support member against the fixing surface side member, a fixing nip that narrowly holds and conveys the paper is formed.

The fixing unit 60 secondarily transfers the toner image, and heats and pressurizes the conveyed paper with the fixing nip to fix the toner image on the paper. The fixing portion 60 is arranged as a unit in the fixing device F.

The paper transport unit 50 includes a paper feed unit 51, a paper discharge unit 52, a transport path unit 53, and the like. Paper S (standard paper, special paper) identified based on the basis weight (rigidity), size, etc. is set in the three paper feed tray units 51a to 51c constituting the paper feed unit 51 for each preset type. Be housed. The transport path portion 53 has a plurality of transport rollers such as a resist roller pair 53a and a loop roller 53b, a double-sided transport path for forming an image on both sides of paper, and the like. The resist roller pair 53a corresponds to the "paper transport member" of the present invention.

The resist roller pair 53a corrects the position of the paper S in the width direction under the control of the control unit 100. Specifically, when the paper S is sandwiched between the nips of the resist roller pair 53a, the resist roller pair 53a moves in the width direction to control the resist swing to move the paper S, thereby controlling the paper S. The position in the width direction is corrected. The control content of such resist swing will be described later.

The loop roller 53b is a pair of rollers arranged on the upstream side of the pair of resist rollers 53a in the transport direction. The loop roller 53b corrects the bending of the paper S by rotating under the control of the control unit 100 so as to form a loop on the paper S between the resist roller and the 53a.

After correcting the position of the paper S in the width direction, the resist roller pair 53a is returned to the position before the paper S finishes passing through the resist roller pair 53a, that is, separated during the transportation of the paper S and before moving. Is done. Then, the resist roller pair 53a is crimped again after the rear end of the paper S has passed.

Further, the transfer speed of the paper S in the resist roller pair 53a is set to be faster than the transfer speed of the paper S in the secondary transfer nip formed by the backup roller 423B and the secondary transfer roller 424 under the control of the control unit 100. Will be done.

A line sensor 54 is arranged on the downstream side of the resist roller pair 53a in the paper transport direction and on the upstream side of the secondary transfer nip. The line sensor 54 is a sensor in which photoelectric conversion elements are arranged in a line shape, detects one end of the paper S in the width direction (hereinafter referred to as a side end), and causes the paper S to be offset (from a reference position). It plays a role of detecting deviation).

The paper S housed in the paper feed tray units 51a to 51c is sent out one by one from the uppermost portion, and is conveyed to the image forming unit 40 by the transfer path unit 53. At this time, the resist roller pair 53a corrects the inclination (skew correction) of the fed paper S and adjusts the transfer timing.

Then, in the image forming unit 40, the toner image of the intermediate transfer belt 421 is collectively secondarily transferred to one surface of the paper S, and the fixing step is performed in the fixing unit 60. The image-formed paper S is discharged to the outside of the machine by the paper ejection unit 52 provided with the paper ejection roller 52a. At the time of double-sided printing, the paper S on which the image is formed on the first side is turned over on the front and back through the double-sided transport path, and then the toner image is secondarily transferred and fixed on the second side. Paper is discharged to the outside of the machine by the paper ejection unit 52.

By the way, in the image forming apparatus, a phenomenon (secondary scanning bending) occurs in which the paper transport direction is bent in the sub-scanning direction due to the misalignment from the resist roller pair 53a to the fixing nip via the secondary transfer nip. There's a problem. In addition to the above-mentioned misalignment, such sub-scanning bending is likely to occur when there is a difference in the diameters of both ends in the paper width direction (sub-scanning direction) of the roller due to durability or the like. Further, since long paper having a long size in the transport direction is easily affected by the above, sub-scanning bending occurs remarkably (see FIGS. 3A and 5A). Since such sub-scanning bending causes image defects due to misalignment and distortion of the image transferred by the transfer unit, there is a demand for a technique for suppressing sub-scanning bending.

Conventionally, to solve this problem, the resist swing control that monitors the position of the side edge of the paper S detected by the line sensor 54 and swings the resist roller pair 53a when the position of the side edge is displaced. Was going. Further, in the conventional resist swing control, the main focus is on the control of swinging the resist roller pair 53a before the tip of the paper S rushes into the transfer portion. Such conventional resist swing control will be described with reference to FIG.

FIG. 3 (FIGS. 3A and 3B) is a diagram illustrating conventional control of resist rocking when long paper is conveyed as paper S, and the paper conveying direction is detected by the line sensor 54 with an arrow Y. The position of the reference end of the paper is indicated by a dotted line, and the swing direction of the resist roller pair 53a is indicated by an arrow X. Further, the rollers separated from the paper S are shown by dotted lines.

FIG. 3A shows an example in which the paper S (long paper) is conveyed in a state of being entirely shifted to the right side (back side) on the upstream side of the backup roller 423B forming the secondary transfer nip. In this case, the control unit 100 detects the deviation direction and the deviation amount of the side edge of the paper S from the output signal of the line sensor 54, and calculates the swing direction and the amount of the resist roller pair 53a from the detection result. Then, the control unit 100 controls to swing the resist roller pair 53a in the X direction orthogonal to the paper transport direction Y according to the calculated value, as shown in FIG. 3B.

Further, the control unit 100 controls the roller (loop roller 53b in the example of FIG. 3) on the upstream side of the resist roller pair 53a in the transport direction so as to be separated from the paper S in order to perform such resist swing control. Therefore, the paper S is conveyed only by the resist roller pair 53a before and after the resist roller pair 53a is swung.

On the other hand, in the conventional resist swing control, the resist roller pair 53a swings only before the tip of the paper S rushes into the secondary transfer nip, so that the sub-scanning of the paper S bends after the resist swing. When (skew, etc.) occurs, there is a problem that image shift or distortion occurs. In particular, in long paper, the longer the length of the paper S, the more remarkable this problem becomes.

Further, when the above-mentioned inclination (skew) of the paper S is skew-corrected by the resist roller pair 53a, the front end side of the paper S is corrected, but in the case of long paper, the inclination of the rear end of the paper can be corrected. Since this is not possible, distortion remains on the front end side and the rear end side, and sub-scanning is likely to occur.

In order to deal with such a problem, it is conceivable to repeatedly swing the resist after the tip of the paper S (long paper) has rushed into the secondary transfer nip.

However, in the conventional resist swing control, basically, the deviation from the reference position of the side edge of the paper S is detected by the line sensor 54, and the swing amount of the resist roller vs. 53a is determined from the detection result. The resist roller pair 53a was oscillated at the determined value. Therefore, in the conventional resist swing control, the side edge of the paper S may shift from the reference position when the swing is stopped.

In particular, when the size of the paper S in the transport direction is long, when the resist roller pair 53a swings, the secondary transfer nip and the fixing member on the downstream side thereof, and other transports that do not have the separation mechanism on the upstream side. A roller (such as a paper feed roller of an optional device) may be in contact with or crimping the paper. In such a case, in the conventional resist swing control in which the resist roller pair 53a is swung by the amount of deviation of the side edge of the paper S detected by the line sensor 54, excess or deficiency of the swing amount is likely to occur.

On the other hand, as for the sub-scanning bend, as described above, the bending method and the bending amount vary depending on individual differences in each machine such as alignment and front-back difference of each roller, but the image forming apparatus 1 is installed in a room or the like. After that, it does not collapse significantly, and each machine has a certain bending method and bending amount. That is, with respect to the sub-scanning bend, after the image forming apparatus 1 is installed in a room or the like, it is often the case (when it can be predicted) that the direction in which the paper S shifts or the time when the paper S begins to shift is known in advance due to the peculiar habit of each device. ..

As a result of conducting various experiments based on such findings, the present inventors basically depend on the detection result of the line sensor 54 with respect to the start of the resist rocking operation in order to correct the sub-scanning bend. It has been found that there is no need to perform resist swing control based on a preset value for swinging the resist roller pair 53a.

In the configuration described below, the control unit 100 basically does not use the value detected by the line sensor 54 with respect to the start of the swing operation of the resist roller pair 53a, and swings in the direction of swinging the resist roller pair 53a. The resist swing control is performed using a predetermined fixed value (preset value) for the number of swings, the amount of each swing, the swing timing (swing point), and the like.

In the present embodiment, the number of swing points for one sheet S, the swing direction and swing amount of the resist roller pair 53a at each swing point, and the like can be arbitrarily specified as preset values.

On the other hand, when the swing direction of the resist roller pair 53a at each swing point is always one direction (for example, to the left), the side edge of the paper S exceeds the target position when the swing is stopped (so-called overrun). When) occurs), it may not be possible to restore the side edge of the paper S to the target position.

In view of the above-mentioned problems, in the present embodiment, the resist roller pair 53a is resisted by using a preset value defined to swing the resist roller pair 53a both left and right (width direction) with respect to one sheet of paper S. Swing. Specifically, the resist roller pair 53a is swung a plurality of times (N times, for example, 5 times) with respect to one sheet S, and the side edge of the sheet S is directed toward the target position in the first direction and the first. The resist swing is performed using a preset value specified so that the operations of the second direction opposite to the direction are alternately performed.

In addition, in the present embodiment, the control unit 100 starts swinging the resist roller vs. 53a, that is, moving the paper S in the width direction, and then swings the resist roller vs. 53a based on the detection result of the line sensor 54. Executes stop control to stop the movement.

Hereinafter, the basic control method of resist swing control (stop control) in the present embodiment will be described in comparison with the conventional control method with reference to the timing chart shown in FIG. Here, FIG. 4A shows an example of a signal sequence of resist swing control by a conventional control method, and FIG. 4B shows an example of a signal sequence in resist swing control of the present embodiment. In the figure, the control signal output for the swing operation of the resist roller pair 53a and the control signal output to the line sensor 54 are shown in chronological order, and the rising state of each signal is turned on. That is, the resist roller pair 53a moves in the width direction while the swing is on, and the side edge of the paper S is detected while the line sensor 54 is on.

In the conventional resist swing control, when the print job is started, the paper S is conveyed toward the secondary transfer nip, the tip of the paper S passes through the position of the line sensor 54, and then the side edge of the paper S is reached. The position (positional deviation) can be detected by the line sensor 54. Therefore, the control unit 100 calculates the swing amount, that is, the swing direction and the movement amount of the resist roller pair 53a from the detection result (see FIG. 4A), and moves and stops the resist roller pair 53a in the paper width direction according to the calculation result. Controls the rocking of the resist.

That is, as shown in FIG. 4A, in the conventional resist swing control, the line sensor 54 is operated before the start of swing of the resist roller pair 53a, and the resist roller pair 53a is operated during the period indicated by the double-headed arrow in the figure. The amount of swing was calculated, and after such calculation, the swing of the resist roller pair 53a was started. Then, the control unit 100 controls to stop the swing of the resist roller pair 53a at the timing when the movement with the calculated swing amount ends (see FIG. 4A). In other words, in the conventional resist swing control, the detection result of the side edge of the paper S by the line sensor 54 is only used for starting the swing of the resist roller pair 53a and calculating the swing amount.

Therefore, in the conventional resist swing control, as shown by the double-headed arrow in FIG. 4A, the swing amount of the resist roller pair 53a is calculated from the time of detection by the line sensor 54 to the start of movement of the resist roller pair 53a. There is a time lag due to the processing time. The larger the time lag, the more likely it is that a difference (error) will occur between the amount of misalignment at the time of measurement and the amount of misalignment at the start of rocking, and the side of the paper S when the movement of the resist roller vs. 53a is stopped. There is a problem that the edge tends to deviate from the correct position (see the dotted line in FIG. 3).

Further, in the conventional resist swing control, the swing amount (movement amount in the width direction) of the resist roller pair 53a is already determined at the start of swing of the resist roller pair 53a (see FIG. 4A). Therefore, when passing a long paper having a long transport direction so that the front end or the rear end side of the paper S is pressed by a roller other than the resist roller pair 53a (see FIG. 5A), the swinging operation is in progress. In some cases, the paper S slips with respect to the resist roller pair 53a, and the misalignment cannot be eliminated with the determined swing amount.

As described above, according to the conventional resist swing control using the line sensor 54 for calculating the swing amount of the resist roller pair 53a and starting the swing, when the resist roller pair 53a swing is stopped (see FIG. 4A). , The side edge of the paper S may not match the correct position. In particular, in the conventional resist swing control, an error is likely to occur when a long paper is conveyed as the paper S.

On the other hand, in the resist swing control of the present embodiment, since the line sensor 54 is used to stop the swing of the resist roller pair 53a, the above error in the resist swing is significantly reduced. Can be done.

Specifically, as shown in FIG. 4B, in the present embodiment, the resist roller vs. 53a swings (in the width direction) at the timing when the side edge of the paper S coincides with the target position (see the dotted line in FIG. 3A). Controls to stop (move to). In FIG. 4B, after the start of rocking of the resist roller pair 53a, the side edge of the paper S is detected (sensing) by the line sensor 54 a plurality of times at a fixed cycle, and the side edge of the paper S is set to the target position by the third sensing. The case where the resist roller pair 53a is stopped is illustrated. As another control example, the control unit 100 may calculate (predict) the timing at which the side edge of the paper S reaches the target position from the first sensing result, and perform the second sensing at the predicted timing. .. Alternatively, the control unit 100 may omit the second sensing and stop the movement (swing operation) of the resist roller pair 53a at the predicted timing. By controlling the stop, the number of times the line sensor 54 is operated can be reduced and the life of the line sensor 54 can be extended.

As described above, according to the present embodiment in which the detection signal of the line sensor 54 is used to stop the rocking of the resist roller pair 53a, the resist roller pair 53a is at the timing when the side edge of the paper S coincides with the target position. You can stop the movement. By such control, the above-mentioned error at the time of stopping the rocking of the resist swing can be significantly reduced.

A method for controlling rocking stop in the present embodiment when long paper is conveyed as paper S will be described with reference to FIGS. 5A and 5B. In the figure, the paper transport direction is indicated by an arrow Y, the position of the reference end of the paper detected by the line sensor 54 is indicated by a dotted line, and the swing direction of the resist roller pair 53a is indicated by an arrow X. Further, in this example, it is assumed that a paper feed device as an optional device (not shown) is connected to the image forming device 1 shown in FIG. 1, and the paper feed device is connected to the upstream side of the resist roller pair 53a. Paper feed roller 500 is arranged.

As described above in FIG. 3, in the conventional resist rocking, other rollers such as the loop roller 53b on the upstream side of the resist roller pair 53a are controlled to be separated from each other. In other words, in the conventional resist swing control, only the resist roller pair 53a is pressed against the paper S, and the resist roller pair 53a swings in a state where the thrust resistance is eliminated. On the other hand, in the paper S (long paper) having a long length in the transport direction, when the front end side of the paper is sandwiched between the resist roller pair 53a, the rear end side of the paper is fed as shown in FIGS. 5A and 5B. It may be crimped to another paper transport member such as the roller 500, and in such a case, the position correction on the rear end side of the paper cannot be performed.

In the resist swing control of the present embodiment, even when the paper S is pressed by a plurality of rollers upstream and downstream of the resist roller pair 53a, the side edge of the paper S is set as a target value, that is, a reference. Since it can be adjusted to the position, it is particularly effective in such a case. Therefore, as shown in FIGS. 5A and 5B, the resist swing control in the present embodiment may be performed after the tip of the paper S enters the secondary transfer nip formed by the backup roller 423B or the like.

On the other hand, if the paper S has a short size in the transport direction, the entire paper S can be swung (moved in the width direction) with one swinging operation, whereas the paper S has a long size in the transport direction. In the case of paper, the entire paper S may not move in one rocking operation. In other words, in the case of long paper having a long size in the transport direction of the paper S, the resist roller pair 53a is rocked in only one direction (left or right) in one swinging operation to move the side edge of the paper S. Even if it is stopped at the target position, the amount of swing may still be insufficient.

Specifically, as shown in FIG. 1 and the like, in the image forming apparatus 1, a secondary transfer nip is arranged on the upstream side of the line sensor 54 in the paper transport direction. On the other hand, in the present embodiment, basically, the side edge of the paper S is controlled to be aligned with the target position at the position of the line sensor 54. For this reason, for example, when the entire side edge of the long paper is shifted to the right or left with respect to the target position, and the paper portion on the upstream side of the resist roller pair 53a is pressed by the paper feed roller or the like. Assuming that, even if the side edge of the paper S is aligned with the target position, the amount of swing may be insufficient. That is, even if the side edge of the paper S reaches the target position at the position of the line sensor 54, there is a possibility that the side edge of the paper S in the secondary transfer nip does not reach the correct position.

Therefore, in the present embodiment, in the case of long paper in which the length of the paper S in the transport direction exceeds a predetermined value, the resist roller pair 53a is swung in both the left and right directions by using the preset values described above, and each of them is used. The resist swing control is performed to stop the swing based on the detection result of the line sensor 54.

Specifically, the control unit 100 swings the resist roller pair 53a in the direction in which the side edge of the paper S faces the target position according to the swing timing (swing point) and the swing direction defined in the preset values. The first swing is started, the line sensor 54 is operated during the first swing, and the control is performed to stop the first swing based on the detection result of the line sensor 54. Subsequently, the control unit 100 performs a second swing that swings the resist roller pair 53a in the direction opposite to the first swing according to the swing timing (swing point) and the swing direction defined in the preset values. The line sensor 54 is operated during the second swing, and control is performed to stop the second swing based on the detection result of the line sensor 54. The details of the control of the first swing and the second swing will be described later.

Here, when the length of the paper S in the transport direction exceeds a predetermined value, it cannot be accommodated in the in-machine paper feed tray units 51a to 51c and is connected to the image forming apparatus 1 as an optional device, which is not shown. This is a case where the length cannot be accommodated in the paper feed tray of the paper device. For example, the size of the paper S in the transport direction may exceed 487.7 mm. Long paper of such a size can be fed by connecting a paper feeding device dedicated to the long paper to the image forming apparatus 1.

Alternatively, when the length of the paper S in the transport direction exceeds a predetermined value, it is located upstream of the resist roller pair 53a in the transport direction from the position of the resist roller pair 53a, has no crimp separation mechanism, and is always with respect to the paper. This is the case when the length is longer than the distance to the roller to be crimped.

When the length of the paper S in the transport direction is equal to or less than the above-mentioned predetermined value, the control unit 100 resists with the resist swing control by the conventional method described above in FIG. 4A or the like, that is, the swing amount based on the detection result of the line sensor 54. Control is performed to swing the roller pair 53a.

Next, an example of resist swing control in the case of a long paper in which the length of the paper S in the transport direction exceeds a predetermined value (for example, 487.7 mm) will be described with reference to FIGS. 6A to 6D.

When the print job is executed, the paper S (long paper) is fed to the image forming apparatus 1 from, for example, a paper feeding device dedicated to long paper, and is registered through the transport path portion 53, as described above in FIG. The roller pair 53a is sequentially conveyed to the secondary transfer nip. Here, FIG. 6A illustrates a case where the side edge position of the paper S can be detected by the line sensor 54 and the side edge of the paper S is displaced to the right side. Further, as shown by a broken line in the drawing, the loop roller 53b is separated from the paper S prior to the resist rocking operation.

FIG. 6B illustrates a state immediately before the start of rocking of the resist roller pair 53a. As shown by arrows X1 and X2 in FIG. 6B, the resist roller pair 53a is configured to be reciprocally movable in the width direction (both left and right directions) orthogonal to the arrow Y direction, which is the paper transport direction.

Here, as shown in FIG. 6C, the control unit 100 directs the side edge of the paper S toward the target position (see the dotted line in the figure) according to the preset value in the first direction (left in the illustrated example, that is, the arrow X1 direction). ), The resist roller pair 53a is operated so as to start swinging to). Subsequently, the control unit 100 operates the line sensor 54 to detect the position of the side edge of the paper S (see FIG. 4B), and stops the rocking of the resist roller vs. 53a based on the detection result. Here, in the case of eliminating the insufficient swing on the rear end side of the paper S described above, the control unit 100 sets the resist roller pair at a position where the side end of the paper S slightly exceeds the target position (see FIG. 6D). It is preferable to control so as to stop the swing of 53a.

Further, from this state, the control unit 100 starts swinging in the second direction (right, that is, the arrow X2 direction in the illustrated example) opposite to the first direction, as shown in FIG. 6D, according to the preset value. In addition, the resist roller pair 53a is operated. Subsequently, the control unit 100 operates the line sensor 54 to detect the position of the side edge of the paper S (see FIG. 6B), and stops the rocking of the resist roller vs. 53a based on the detection result. At this time, similarly to the above, the control unit 100 can control the resist roller vs. 53a to stop swinging at a position where the side edge of the paper S slightly exceeds the target position (see FIG. 6D). Alternatively, the control unit 100 may stop the swing of the resist roller pair 53a so that the side edge of the paper S reaches or matches the target position.

For example, when five swings (five swing points) are specified for one sheet of paper S as a preset value, the control unit 100 sets the resist roller pair 53a in the arrow X1 direction and the X2 direction. , X1 direction, X2 direction, and X1 direction. Then, in each of these swinging operations, the control unit 100 controls so as to stop the swinging of the resist roller vs. 53a at each swinging amount specified in the preset value based on the detection result of the line sensor 54.

In the swinging operation in the first direction (arrow X1 direction) or the second direction (arrow X2 direction) during the series of operations described above, the deviation position (deviation amount) when offset from the dotted line position in FIG. 6 is determined. It can be set to any preset value. The shift position (shift amount) may be adjusted by the user through, for example, a setting screen (not shown).

In terms of the amount of swing (movement distance in the width direction) of the resist roller pair 53a, in many cases, the swing operation in the first direction and the swing operation in the second direction are in the first direction. The swing amount of the swing operation becomes large. Therefore, the control unit 100 may operate the resist roller pair 53a so that the rocking speed in the first direction is faster than the rocking speed in the second direction.

As described above, in the resist swing control of the present embodiment for one sheet of paper S (long paper), the swing in the first direction is started and the stop is based on the detection result of the line sensor 54 according to the preset value. And the start of the swing in the second direction and the stop based on the detection result of the line sensor 54 are alternately executed. As described above, according to the present embodiment in which the resist roller pair 53a is controlled to swing back and forth so as to reciprocate from side to side, it is possible to effectively prevent the occurrence of image defects due to the sub-scanning bend, especially on long paper. be able to.

For convenience of explanation, FIG. 6 shows a diagram in which the swinging operation is started and stopped in both the left and right directions before the tip of the paper S rushes into the secondary transfer nip. On the other hand, in the actual transfer of long paper, the sub-scanning bend (positional deviation) after the tip of the paper S enters the secondary transfer nip is often a particular problem. That is, after the tip of the paper S enters the secondary transfer nip, the paper S is pressed against the transport member by both the upstream side and the downstream side of the resist roller pair 53a, so that the tip of the paper S is the secondary transfer nip. An error in the resist swing operation (usually insufficient swing) is more likely to occur than before the resist swing operation.

Therefore, in the present embodiment, when the length of the paper S in the transport direction exceeds the above-mentioned predetermined value, the series of operations by the first swing and the second swing described in FIG. 6 is basically performed on the paper. This is performed after the tip of S has entered the secondary transfer nip. Before the tip of the paper S rushes into the secondary transfer nip, the resist swing control that performs both the first swing and the second swing may be performed, but basically, the above-mentioned conventional method is used. That is, control for swinging the resist roller pair 53a with a swing amount based on the detection result of the line sensor 54 (see FIG. 4A) may be performed.

Further, when the length of the paper S in the transport direction is equal to or less than the above-mentioned predetermined value, it is possible to select to perform resist swing control including the first swing and the second swing through a user selection screen (not shown) or the like. You may. Alternatively, the control unit 100 may determine whether or not the resist swing control including the first swing and the second swing is performed depending on the type of the paper S (such as the basis weight).

Hereinafter, an example of the preset value will be described in more detail. The preset value defines the start timing of each swing of the resist roller vs. 53a from the time when the paper S is inserted into the secondary transfer nip until the paper S exits the resist nip. That is, the preset value is defined as a value indicating the timing (swing timing) at which the side end of the resist roller pair 53a starts swinging toward the target position after the start of intrusion of the paper S into the secondary transfer nip. .. A plurality of such swing timings can be set for one sheet of paper S. When a plurality of swing timings are set for one sheet of paper S, the interval between the timings can be arbitrarily set. As a whole, the preset value includes a value that defines the timing of starting the movement of the resist roller vs. 53a in the paper width direction or the point on the paper S over the entire length of the paper S in the transport direction.

For example, when the paper S is a long paper, it is preferable to specify (set) a plurality of swing start timings in the preset values so that the series of operations by the first swing and the second swing described above are repeatedly performed.

Further, in the case of long paper in which the length of the paper S in the transport direction exceeds a predetermined value (for example, 487.7 mm), the above-mentioned first is performed while the rear end side of the paper S is pressed by the paper feed roller or the like. It is preferable to specify (set) a plurality of swing start timings in the preset values and set the swing amount at each swing timing so that a series of operations by the first swing and the second swing are repeatedly performed. With such a setting, the resist roller pair 53a repeatedly swings to the left and right, so that the rear end side of the paper S also approaches the target position.

Further, the preset value may specify a value indicating the time from the stop of the first swing to the start of the second swing. That is, in the case of long paper in which the length of the paper S in the transport direction exceeds a predetermined value (for example, 487.7 mm), the second swing is not started immediately after the operation of the first swing is completed, and the first swing is performed. By starting the second swing after a predetermined time from the completion of the operation, the rear end side of the (long paper) may be more easily approached to the target position. A value indicating the time from the stop of the first swing to the start of the second swing can be specified for each swing timing (swing point).

Further, the preset value may include a value indicating the swing speed of the resist roller pair 53a in the first swing or the second swing described above. The value of the swing speed may be specified for each swing timing (swing point).

On the other hand, when the image forming conditions at the time of executing the print job, for example, the environment around the image forming apparatus 1 and the type of the paper S to be used are different, the timing at which the sub-scanning bending of the paper S occurs may be different. In such a case, if the timing of the start of rocking of the resist roller pair 53a and the time interval (interval) of each rocking are uniformly applied, an error occurs, that is, the first rocking with respect to the occurrence of the sub-scanning bend. There is a risk that the start time of the motion will be delayed, or vice versa. In other words, it is considered that the preferable timing of each swing in the resist roller pair 53a differs depending on the image forming conditions.

Therefore, the control unit 100 may change the timing of performing the first swing and the second swing according to the image forming conditions. For example, the control unit 100 corrects the preset value so as to change the timing of the start of each swing of the resist roller pair 53a defined by the preset value and the interval between the swings. In this case, the control unit 100 adds or multiplies the preset value by a correction value or a correction coefficient (ratio) according to the image formation condition, changes the preset value, and resists using the changed preset value. Controls rocking.

Here, the image forming conditions include the type of paper S (for example, length, width, surface glossiness, basis weight (rigidity), etc.), and the environment around the image forming apparatus 1 (typically, temperature and humidity). Conditions), coverage (printing rate), printing surface (first surface or second surface) at the time of double-sided printing, and various other conditions can be mentioned. Considering this, it is advisable to register the above correction values and correction coefficients in individual tables according to each condition. In this case, the control unit 100 specifies the type of paper S and the like at the time of executing the print job, reads out the correction value and the correction coefficient of the corresponding table, changes the preset value, and uses the changed preset value. Controls the swing of the resist.

Alternatively, the timing of the start of swing and the interval between swings may be predetermined as preset values according to the image formation conditions. Here, in view of the wide variety of image formation conditions as described above, it is advisable to register the preset values in the individual tables corresponding to each of these conditions. In this case, the control unit 100 specifies the type of paper S and the like at the time of executing the print job, reads out the preset values of the corresponding table, and controls the resist swing.

Hereinafter, an example of the operation related to the swing control of the resist roller pair 53a and the paper S in the image forming apparatus 1 will be described with reference to the flowchart of FIG. 7. The flow chart shown in the figure is for a long paper in which the size of the paper S in the transport direction exceeds 487.7 mm, and is a print job when the above-mentioned paper feed device dedicated to the long paper is connected to the image forming apparatus 1. Is executed for each sheet of paper S on which an image is formed.

When the print job is executed, the control unit 100 acquires information on the type (length, width, glossiness, basis weight (rigidity), etc.) of the paper S to be printed from the user setting information of the print job ( Step S100).

In step S120, the control unit 100 reads out the preset values registered in the table corresponding to the acquired image forming conditions (paper type in this example), and swings the resist roller vs. 53a at each swing point. Set the direction, swing amount, etc.

Subsequently, the control unit 100 waits until the paper S rushes into the secondary transfer nip (step S140, NO), and when the paper S rushes into the secondary transfer nip (step S140, YES), the process proceeds to step S160. ..

In step S160, the control unit 100 controls to start swinging the resist roller pair 53a in the first direction (first swinging) at a timing and direction according to a set value, that is, a preset value (FIG. FIG. See 6C).

By such control, the resist roller pair 53a swings in the direction of correcting the misalignment of the paper S at the timing according to the preset value with respect to the paper S that has entered the secondary transfer nip, and the paper S swings with the swing. Swing in the width direction.

At this time, the front end side of the paper S (long paper) is sandwiched between the secondary transfer nips and conveyed while the toner image is formed, and the rear end side of the long paper is a long paper optional device. Is conveyed while being pressed by the paper feed roller 500 in the paper feed tray unit (see FIG. 5A).

In the following step S180, the control unit 100 turns on the line sensor 54, detects the position of the side edge of the paper S, and based on the detection result by the line sensor 54, the first direction with the swing amount specified in the preset value. The resist roller pair 53a is controlled so as to stop the swing of the resist roller pair 53a. In the swinging operation in the first direction, the control unit 100 does not stop at the timing when the side edge of the paper S reaches the target position (reference position), and as described above, the side edge slightly moves the reference position. The resist roller pair 53a can be stopped at a position that exceeds (so-called overrun position).

After stopping the resist roller pair 53a, the control unit 100 moves in the second direction (see FIG. 6D), which is the opposite direction of the first direction, at the next swing timing (swing point) specified in the preset value. The resist roller pair 53a is controlled so as to start swinging (second swinging) (step S200). At the time of the swing in the second direction, the control unit 100 controls the resist roller pair 53a so as to swing at a speed slower than the swing speed in the first direction.

In the following step S220, the control unit 100 turns on the line sensor 54 again to detect the position of the side edge of the paper S, and based on the detection result by the line sensor 54, the shaking amount specified in the preset value is used. The resist roller pair 53a is controlled so as to stop the movement.

After that, the control unit 100 controls to repeat the swing start of the resist roller pair 53a at the timing according to the preset value and the swing stop based on the detection result of the line sensor 54 according to the setting content in step S120. (Step S240).

By performing such control, the side edge of the paper S in the region of the secondary transfer nip can be accurately aligned with the target position (reference position), and the occurrence of image defects is effectively prevented, and as a result, the occurrence of image defects is effectively prevented. Sub-scanning bends on paper are corrected more correctly.

Thus, when the resist swing of the number of times specified in the preset value for one sheet of paper is completed, the control unit 100 determines in step S260 whether or not the print job is completed. As a result of such determination, when the print job is not completed (step S260, NO), the control unit 100 returns to step S100 and print processing such as swing control of the resist roller vs. 53a and image formation for the next paper S. I do. On the other hand, when the print job is completed (step S260, YES), the control unit 100 ends the series of processes described above.

As described in detail above, according to the present embodiment, it is possible to correct the sub-scanning bend of the paper S due to the misalignment and the difference in diameter in the width direction of each roller, and by extension, the sub-scanning. It is possible to prevent the occurrence of image misalignment or the like due to scanning method bending. Further, according to the present embodiment in which the rocking stop of the resist roller pair 53a is controlled based on the detection result of the side edge of the paper S by the line sensor 54, the paper is compared with the conventional resist rocking control. The sub-scanning bend can be corrected more accurately.

Further, according to the present embodiment in which a series of control of the first swing (start and stop) and the second swing (start and stop) of the resist roller pair 53a is performed, the length in the region of the secondary transfer nip is long. The side edges of the paper can be aligned in the correct position. Therefore, according to the present embodiment, it is possible to correct the sub-scanning bend of the paper S more correctly as compared with the conventional control, that is, to correct it so as to effectively prevent the occurrence of image defects.

In the above-described embodiment, an example of an image forming apparatus including a transfer unit for secondarily transferring an image to be printed using the intermediate transfer belt 421 to paper S has been described. On the other hand, the above-described embodiment can be similarly applied to a transfer-type image forming apparatus (for example, a monochrome printer) that temporarily transfers an image to be printed onto paper S.

In the above-described embodiment, the case where the paper transport member provided on the upstream side of the secondary transfer nip and controlled to swing by the control unit 100 is the resist roller pair 53a has been described. As another example, as the paper transport member, for example, a roller other than the resist roller pair 53a, a paper transport guide, and the like can be additionally or alternately applied.

In the above-described embodiment, a case where a sheet of paper is used as the paper S has been described. On the other hand, the above embodiment can be similarly applied to roll paper.

In addition, the above embodiments are merely examples of embodiment of the present invention, and the technical scope of the present invention should not be construed in a limited manner by these. That is, the present invention can be implemented in various forms without departing from its gist or its main features.

1 Image forming device 20 Operation display unit 30 Image processing unit 40 Image forming unit 50 Paper transport unit 53a Resist roller pair (paper transport member)
53b Loop roller 54 Line sensor (detector)
100 Control unit 421 Intermediate transfer belt 423B Backup roller 424 Secondary transfer roller 500 Paper feed roller for paper feed device

Claims (12)

A transfer unit that transfers images to paper,
A paper transport member provided on the upstream side of the transfer unit in the paper transport direction to transport the paper, and a paper transport member.
A control unit for controlling the swing of the paper transport member so as to swing the paper along the width direction of the paper is provided.
Wherein, the previous SL the first swing the first swing and the sheet transport members which end portion in the width direction swings the sheet transport members in a direction toward the target position of the sheet in the reverse direction Control is performed to alternately execute the first swing and the second swing by using a preset value predetermined for the paper as the execution timing for alternately performing the second swing to be shaken.
The preset value defines the amount of swing of the first swing and the second swing.
Image forming device. A transfer unit that transfers images to paper,
A paper transport member provided on the upstream side of the transfer unit in the paper transport direction to transport the paper, and a paper transport member.
A control unit for controlling the swing of the paper transport member so as to swing the paper along the width direction of the paper is provided.
The control unit swings the paper transport member in a direction in which the end portion in the width direction of the paper swings toward a target position, and swings the paper transport member in the direction opposite to the first swing. Using a preset value predetermined for the paper, the execution timing for alternately performing the second swing to be moved is controlled to alternately execute the first swing and the second swing.
The preset value includes a value indicating a swing speed in the first swing or the second swing.
Image forming device. A transfer unit that transfers images to paper,
A paper transport member provided on the upstream side of the transfer unit in the paper transport direction to transport the paper, and a paper transport member.
A control unit for controlling the swing of the paper transport member so as to swing the paper along the width direction of the paper is provided.
The control unit swings the paper transport member in a direction in which the end portion in the width direction of the paper swings toward a target position, and swings the paper transport member in the direction opposite to the first swing. Using a preset value predetermined for the paper, the execution timing for alternately performing the second swing to be moved is controlled to alternately execute the first swing and the second swing.
A table in which the preset values are defined according to the image formation conditions is provided.
Image forming device. A transfer unit that transfers images to paper,
A paper transport member provided on the upstream side of the transfer unit in the paper transport direction to transport the paper, and a paper transport member.
A control unit for controlling the swing of the paper transport member so as to swing the paper along the width direction of the paper is provided.
The control unit swings the paper transport member in a direction in which the end portion in the width direction of the paper swings toward a target position, and swings the paper transport member in the direction opposite to the first swing. The execution timing for alternately executing the second swing to be moved is controlled by alternately executing the first swing and the second swing by using a preset value predetermined for the paper. The execution timing of the first swing and the second swing is changed according to the image formation conditions.
Image forming device. After the operation of the first swing and the second swing is started, the control unit is the end portion detected during the swing operation by the detection unit that detects the end position of the paper in the width direction. Control to stop the swing based on the position,
The image forming apparatus according to any one of claims 1 to 4. The control unit executes control of the first swing and the second swing after the tip of the paper enters the transfer unit.
The image forming apparatus according to any one of claims 1 to 5. The size of the paper in the paper transport direction is equal to or larger than a predetermined length.
The image forming apparatus according to any one of claims 1 to 6. The control unit makes the swing speed of the first swing faster than that of the second swing.
The image forming apparatus according to any one of claims 1 to 7. In an image forming apparatus including a transfer unit for transferring an image to paper and a paper transport member provided on the upstream side of the transfer unit in the paper transport direction to transport the paper, the paper is transferred in the width direction of the paper. It is a transport control method that controls the swing of the paper transport member so as to swing along the paper transport member.
The oscillating the width direction of the sheet transport member and the first oscillating end portion swings the sheet transport members in a direction towards the target position in a direction opposite to the first swing before SL paper 2 Control is performed to alternately execute the first swing and the second swing by using a preset value predetermined for the paper for the execution timing of alternately performing the swing.
The preset value defines the amount of swing of the first swing and the second swing.
Transport control method. In an image forming apparatus including a transfer unit for transferring an image to paper and a paper transport member provided on the upstream side of the transfer unit in the paper transport direction to transport the paper, the paper is transferred in the width direction of the paper. It is a transport control method that controls the swing of the paper transport member so as to swing along the paper transport member.
The first swing that swings the paper transport member in the direction in which the end portion of the paper in the width direction toward the target position and the second swing that swings the paper transport member in the direction opposite to the first swing. Control is performed to alternately execute the first swing and the second swing by using a preset value predetermined for the paper for the execution timing of alternately performing the motion.
The preset value includes a value indicating a swing speed in the first swing or the second swing.
Transport control method. In an image forming apparatus including a transfer unit for transferring an image to paper and a paper transport member provided on the upstream side of the transfer unit in the paper transport direction to transport the paper, the paper is transferred in the width direction of the paper. It is a transport control method that controls the swing of the paper transport member so as to swing along the paper transport member.
The first swing that swings the paper transport member in the direction in which the end portion of the paper in the width direction toward the target position and the second swing that swings the paper transport member in the direction opposite to the first swing. Control is performed to alternately execute the first swing and the second swing by using a preset value predetermined for the paper for the execution timing of alternately performing the motion.
A table in which the preset values are defined according to the image formation conditions is provided.
Transport control method. In an image forming apparatus including a transfer unit for transferring an image to paper and a paper transport member provided on the upstream side of the transfer unit in the paper transport direction to transport the paper, the paper is transferred in the width direction of the paper. It is a transport control method that controls the swing of the paper transport member so as to swing along the paper transport member.
The first swing that swings the paper transport member in the direction in which the end portion of the paper in the width direction toward the target position and the second swing that swings the paper transport member in the direction opposite to the first swing. The execution timing for alternately executing the motion is controlled to alternately execute the first swing and the second swing by using a preset value predetermined for the paper, and the first swing and the first swing and the second swing are controlled. The execution timing of the second swing is changed according to the image formation conditions.
Transport control method.

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