JP7196517B2 - CONVEYING DEVICE, CONVEYING METHOD, AND IMAGE FORMING APPARATUS - Google Patents

Description

The present invention relates to a conveying device, a conveying method, and an image forming apparatus.

2. Description of the Related Art An image forming apparatus including a conveying device that conveys sheets is known. In such an image forming apparatus, when "skew" or "misalignment in the width direction" of the sheet being conveyed occurs, if image formation is executed without correcting this, the position of the formed image will not be ideal. out of position. As a result, the image quality will be degraded. Therefore, it is necessary for the conveying device used in the image forming apparatus to appropriately correct the skew of the sheet being conveyed and the misalignment in the width direction.

The conveying device includes a pair of registration rollers for adjusting the transfer timing in order to match the image formation position. This pair of registration rollers temporarily stops conveying the sheet, and restarts the conveying according to the transfer timing. A technique is disclosed in which sensors for detecting a sheet conveyed to the registration roller pair are arranged before and after the registration roller pair, and the registration roller pair is controlled so as to correct the position of the sheet in the conveying direction. (See, for example, Patent Document 1).

According to the technique disclosed in Japanese Patent Application Laid-Open No. 2002-200010, when the input skew including the amount of inclination of the sheet with respect to the conveying direction and the amount of misalignment in the width direction is large, the operation amount of the pair of registration rollers for correcting the skew is large. Become. If the movement amount of the pair of registration rollers becomes large, the position where the sheet is temporarily stopped to adjust the transfer timing to the image forming position will vary. If the sheet stop position by the pair of registration rollers varies, the image forming position (transfer position) on the sheet also varies. Therefore, regardless of the magnitude of the input skew, it is desirable that the sheet stop position by the pair of registration rollers is constant.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a conveying apparatus capable of eliminating advance or delay in conveying a sheet caused by input skew of the sheet being conveyed.

In order to solve the above problems, one aspect of the present invention is to provide a nipping roller that nips and conveys a transported object and corrects the position of the transported object; A first sensor arranged to detect the position of the transported object, a second sensor operating integrally with the nipping roller to detect the transported object, and the transported object detected by the first sensor and a control unit that controls the transport drive of the nipping roller based on the position of the control unit, and the control unit calculates the positional deviation amount of the transported object based on the detection result of the first sensor. and a drive amount calculator for calculating a drive amount related to the conveying drive of the nipping roller based on the position shift amount and the timing at which the second sensor detects the conveyed object. and drive control means for controlling transport driving of the nipping rollers for nipping and transporting the transported object based on the drive amount.

According to the present invention, it is possible to eliminate advance or delay in sheet conveyance caused by input skew of the sheet being conveyed.

1 is a schematic configuration diagram showing an embodiment of an image forming apparatus according to the present invention; FIG. BRIEF DESCRIPTION OF THE DRAWINGS (a) Top view, (b) Side view which shows embodiment of the conveying apparatus which concerns on this invention. FIG. 2 is a hardware configuration diagram of a control unit included in the conveying apparatus according to the embodiment; The functional block diagram of the control part with which the conveying apparatus which concerns on this embodiment is provided. The flowchart which shows 1st embodiment of the conveyance method which concerns on this invention. 4A and 4B are views for explaining a process of conveying a sheet by the conveying device according to the embodiment; FIG. 4A and 4B are views for explaining a process of conveying a sheet by the conveying device according to the embodiment; FIG. 4A and 4B are views for explaining a process of conveying a sheet by the conveying device according to the embodiment; FIG. 4A and 4B are views for explaining a process of conveying a sheet by the conveying device according to the embodiment; FIG. 4A and 4B are views for explaining a process of conveying a sheet by the conveying device according to the embodiment; FIG. 4A and 4B are views for explaining a process of conveying a sheet by the conveying device according to the embodiment; FIG. 4A and 4B are timing charts showing an example of a transport operation in the transport apparatus according to the embodiment; 5 is a timing chart showing another example of the transport operation in the transport apparatus according to the embodiment; 5 is a timing chart showing another example of the transport operation in the transport apparatus according to the embodiment; 5 is a timing chart showing another example of the transport operation in the transport apparatus according to the embodiment; The flowchart which shows 2nd embodiment of the conveyance method which concerns on this invention. 9 is a chart showing examples of transport speeds in the transport method according to the second embodiment; 9 is a chart showing another example of the transport speed in the transport method according to the second embodiment; 9 is a chart showing another example of the transport speed in the transport method according to the second embodiment; The flowchart which shows 3rd embodiment of the conveyance method which concerns on this invention. A chart showing an example of restart timing in the conveying method according to the third embodiment. 9 is a chart showing another example of restart timing in the transport method according to the third embodiment; 9 is a chart showing another example of restart timing in the transport method according to the third embodiment; FIG. 2 is a schematic configuration diagram showing another embodiment of an image forming apparatus according to the present invention;

[Summary of the present invention]
A conveying device according to the present invention includes a registration device having a correction function for correcting "positional misalignment" including skew and widthwise misalignment (horizontal misalignment) that occurs during transportation of a conveyed object, which is a sheet-like recording medium. Prepare. This registration device is provided with a sensor for detecting that an object to be conveyed reaches the registration rollers. When the sensor detects the object to be conveyed, the registration rollers start conveying the sheet, After the elapse of , the conveying operation of the registration rollers is stopped. At this time, one of the gists is to keep the sheet stop position constant regardless of the amount of movement of the registration device to correct the positional deviation, that is, the input skew. Specifically, the amount of positional deviation, which is the amount of positional deviation of the object to be transported, is calculated, and the amount of advance or the amount of delay (advance/delay amount) of the object to be transported is calculated based on the amount of positional deviation. Then, the sheet conveying operation by the registration rollers is controlled so as to eliminate the lead/lag amount. The amount of misalignment includes the amount of skew representing the amount of skew and the amount of lateral misalignment representing the amount of misalignment in the width direction of the conveyed object, which is the plane direction orthogonal to the conveying direction. In this specification, this positional deviation amount is also referred to as "input skew".

The conveying apparatus according to the present invention is capable of adjusting the position (reference stop position) at which the conveyed object is temporarily stopped regardless of the magnitude of correction operation in a mechanism that executes input skew correction or the length of time of the correction operation. To control the conveying operation of an object to be conveyed so as to eliminate the advance of conveying and the delay of conveying. When the conveying device according to the present invention is installed in an image forming apparatus, the "reference stop position" means that the conveyance of the conveyed object is temporarily stopped in order to match the transfer timing of the image to the conveyed object in the image forming process. This is the position to stop. DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a conveying device according to the present invention will be described below with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and redundant description thereof will be appropriately simplified or omitted.

[First Embodiment of Image Forming Apparatus]
First, an embodiment of an image forming apparatus provided with a conveying device according to the present invention will be described with reference to FIG. FIG. 1 is a diagram illustrating the overall configuration of an electrophotographic image forming apparatus 100 according to the present embodiment.

The image forming apparatus 100 has a configuration in which photoconductor drums 134Y, 134M, 134C, and 134K (hereinafter collectively referred to as photoconductor drums 134) of respective colors are arranged along an intermediate transfer belt 135, which is an endless moving means. is. A configuration like the image forming apparatus 100 is called a tandem type. The image forming apparatus 100 includes an intermediate transfer belt 135 on which an intermediate transfer image to be transferred onto the paper 17 fed from the paper feed tray 12 is formed. Along the intermediate transfer belt 135, a plurality of photosensitive drums 134Y, 134M, 134C, and 134K are arranged in order from the upstream side in the direction in which the paper 17 is conveyed.

An image of each color is formed on the surface of the photosensitive drum 134 of each color by developing with toner, which is a coloring agent, and is primarily transferred to the intermediate transfer belt 135 to be superimposed. An image obtained by this primary transfer becomes a full-color image. This full-color image is transported by the intermediate transfer belt 135 to a position closest to the paper transport path 16 indicated by the dashed line in FIG. A full-color image is secondarily transferred from the intermediate transfer belt 135 to the paper 17 by the transfer roller 10 and the opposing roller 11 arranged at that position.

The paper 17 on which the image is secondarily transferred is conveyed downstream of the transfer roller 10 in the conveying direction. A fixing roller 14 is arranged downstream of the transfer roller 10 in the conveying direction. The fixing roller 14 fixes the image transferred to the paper 17 . After that, the paper 17 is conveyed outside the housing of the image forming apparatus 100 . In the case of double-sided printing, after an image is formed on the first surface (front surface) of the paper 17 and the image is fixed, the paper is transported again on the transport path 16 from the branch 161 via the reversing path 162 . .

In this manner, the paper 17 is placed in a state in which image formation is possible on the second surface (back surface), that is, in such a manner that the image formed on the intermediate transfer belt 135 is transferred to the second surface of the paper 17 . In this state, the sheet is conveyed to the transfer position of the transfer roller 10 again. After that, the image is fixed on the sheet 17 on which the image has been transferred to the second side (back side), and the sheet is discharged to the discharge tray 500 via the branch portion 161 .

The image forming apparatus 100 has a function of forming a full-color image on the paper 17, but it is also possible to form a monochrome image using any one of the four photosensitive drums 134Y, 134C, 134M, and 134K. . It is also possible to use two or three photoreceptor drums 134 to form a two-color or three-color image.

A registration device 200, which is an embodiment of the conveying device according to the present invention, is arranged on the upstream side of the transfer roller 10 in the conveying direction. The registration device 200 has a function of conveying the sheet 17 to the transfer roller 10, which is a secondary transfer portion, at a predetermined timing, and corrects the positional deviation of the sheet 17 conveyed in the conveying path 16 with respect to the conveying direction. It has a function to

[Outline of registration device 200]
2A and 2B are a plan view (a) of the registration device 200 as viewed from the photosensitive drum 134 side and a side view (b) of the registration device 200 as viewed from the left in the transport direction. The registration device 200 includes a transport roller pair 20 that transports the paper 17, which is an object to be transported, fed from the paper feed tray 12 along the transport path 16 toward the registration roller pair 221, and a registration roller pair including a registration roller. and a registration roller mechanism 22 comprising 221 . "Transfer roller 10 and opposing roller 11" which constitute a secondary transfer section for secondary transfer of an image formed on an intermediate transfer belt 135 (see FIG. 1) onto a sheet 17 are arranged downstream of the registration device 200 in the conveying direction. are placed. A roller pair corresponding to the transfer timing control section may be arranged on the upstream side of the secondary transfer section in the conveying direction.

A first sensor for detecting the input skew of the paper 17 is arranged between the transport roller pair 20 and the registration roller mechanism 22 (registration roller pair 221). The first sensor includes a first edge sensor 26a that detects the position of the side edge of the paper 17 and a second edge sensor 26b that similarly detects the position of the side edge of the paper 17 . The second edge sensor 26b is arranged downstream of the first edge sensor 26a in the conveying direction. Both the first edge sensor 26a and the second edge sensor 26b are image sensors in which photosensors are arranged in a straight line, and are contact image sensors (CIS) that are also used in image reading devices, for example. is.

Further, as shown in FIG. 2A, the registration device 200 according to the present embodiment has a third edge sensor 26c arranged downstream of the two CISs in the transport direction in order to detect input skew. The third edge sensor 26c is arranged downstream of the registration roller mechanism 22 in the transport direction, and is arranged to detect again the inclination and lateral displacement of the paper 17 after correction based on the input skew. . The third edge sensor 26c is also a CIS like the first edge sensor 26a and the like. The third edge sensor 26c corresponds to the third sensor.

As shown in FIG. 2(a), the first edge sensor 26a, the second edge sensor 26b, and the third edge sensor 26c are all arranged so that the pixel array direction is parallel to the direction perpendicular to the transport direction of the paper 17. It is Therefore, the position of the paper 17 conveyed toward the registration roller mechanism 22 can be detected based on the detection results of the positions of the side edges of the paper 17 by the first edge sensor 26a and the second edge sensor 26b. . That is, the position of the paper 17 with respect to the transport direction of the paper 17 can be detected by the first edge sensor 26a and the second edge sensor 26b. Further, the position of the paper 17 conveyed by the registration roller mechanism 22 can be detected based on the detection result of the position of the side edge of the paper 17 by the third edge sensor 26c.

The registration roller mechanism 22 includes a rotation mechanism 23 that rotates the registration roller pair 221 in the transport direction, and a rotation mechanism 23 that moves the registration roller pair 221 in the width direction of the transported paper 17 (the width direction of the transport path 16). and a shift mechanism 24 . The rotation mechanism 23 and the shift mechanism 24 are mechanisms that perform correction driving for controlling the state (welcoming state) in which the pair of registration rollers 221, which are nipping rollers, welcomes the paper 17 and the correction operation corresponding to the welcoming operation. be. As already explained, the amount of skew in the input skew of the paper 17 is determined by the detection result of the position of the edge of the paper 17 by the first edge sensor 26a and the second edge sensor 26b and the first edge sensor 26a. and the distance (preset) of the second edge sensor 26b. The lateral displacement amount of the input skew of the paper 17 is calculated by, for example, the average value of the positions of the side edges of the paper 17 detected by the first edge sensor 26a and the second edge sensor 26b.

If the paper 17 is ideally conveyed, the position of the paper 17 when it reaches the registration roller mechanism 22 will not be skewed or laterally displaced. In this case, the stop position of the paper 17, which is conveyed by the registration roller mechanism 22 and stopped in order to match the timing of conveyance to the transfer roller 10, is an ideal position. However, if the sheet 17 is skewed or laterally displaced during transportation, the stop position after being transported by the registration roller mechanism 22 deviates from the ideal stop position. If the stop position of the paper 17 by the registration roller mechanism 22 is displaced, the conveyance to the transfer roller 10 is disturbed, which leads to the transfer of the image to the paper 17 being disturbed. In order to solve this problem, the registration device 200 calculates the input skew of the paper 17 based on the detection results of the first edge sensor 26a and the second edge sensor 26b, and then eliminates this input skew to obtain an ideal image. The registration roller mechanism 22 is driven to move the registration roller pair 221 so that the paper 17 can be conveyed to the stop position.

The movement of the registration roller pair 221 is a so-called “welcoming operation”. The registration device 200 starts the pick-up operation before the sheet 17 is detected by the transport sensor 222, which will be described later. Note that the movement of the registration roller pair 221 is executed by the operations of the rotation mechanism 23 and the shift mechanism 24 . Note that the pick-up operation is included in the correction drive for the registration roller pair 221 .

The registration roller mechanism 22 also includes a transport sensor 222 that is a second sensor that detects the paper 17 . The transport sensor 222 is installed at the upstream end of the registration roller mechanism 22 in the transport direction. When the transport sensor 222 detects the leading end of the paper 17 in the transport direction, the registration roller mechanism 22 uses this as a trigger to transport the paper 17 to a stop position where transport of the paper 17 is temporarily stopped in order to adjust the transfer timing. The driving amount of the registration roller pair 221 is controlled. That is, when the transport sensor 222 detects the leading edge of the paper 17 in the transport direction, the registration drive motor 223 that rotates the pair of registration rollers 221 starts operating. As a result, the registration roller pair 221 starts a conveying operation for pinching and conveying the paper 17 .

There is a slight gap between the installation position where the transport sensor 222 is installed and the position where the registration roller pair 221 is arranged in the registration roller mechanism 22 . Therefore, there is a slight time lag until the paper 17 detected by the transport sensor 222 reaches the registration roller pair 221 . The pair of registration rollers 221 starts the transport operation triggered by the detection of the paper 17 by the transport sensor 222 in a state in which this “time lag” is taken into consideration. After that, the paper 17 reaches the pair of registration rollers 221 that are carrying out the carrying operation, and is actually carried.

The registration roller pair 221 is controlled to operate until a predetermined time elapses from the timing at which the transport sensor 222 detects the sheet 17 . Regarding the transport operation of the registration roller pair 221, the transport operation is started after a predetermined time has elapsed from the timing at which the transport sensor 222 detects the sheet 17, and then the transport operation continues until the predetermined time has passed. may be controlled to

In this embodiment, the transport sensor 222 is installed at the upstream end of the registration roller mechanism 22 in the transport direction. The position of the transport sensor 222 is not limited to this. The conveying sensor 222 may be installed at a position where the pair of registration rollers whose tilt and widthwise position change due to the correction operation by the registration roller mechanism 22 can be integrally operated. That is, the transport sensor 222 according to this embodiment does not have to be installed in the registration roller mechanism 22 or the registration roller pair 221 .

[Hardware configuration of registration device 200]
Next, the hardware configuration of the registration device 200 according to this embodiment will be described with reference to FIG. The registration device 200 includes a controller 210 composed of semiconductor elements such as a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory). 24, and a driver 220 for operating a registration drive motor 223, a transport drive motor 224, and the like. The transport drive motor 224 is a motor that drives the transport roller pair 20 . The operation of the transport drive motor 224 controlled by the controller 210 is included in the transport operation performed on the paper 17 to eliminate transport progress and transport delay caused by input skew, as will be described later. drive.

The controller 210 inputs detection results from the first edge sensor 26a and the second edge sensor 26b, which are the first sensors, and the conveying sensor 222, which is the second sensor. It constitutes a computing unit that executes processing. The controller 210 constitutes a control unit that outputs control data for controlling the operation of the pair of registration rollers 221 and the like to the driver 220 based on the result of the arithmetic processing. Specifically, the controller 210 calculates the input skew based on the detection result of the first edge sensor 26a. The controller 210 controls the drive amount and drive timing of the registration drive motor 223 based on the timing at which the second sensor detects the paper 17 and the calculated input skew.

Details of the operation of the registration device 200 having the above configuration will be described later.

[Functional configuration of registration device 200]
Next, functional blocks of the registration device 200 will be described. As shown in FIG. 4, the registration device 200 includes an input skew calculation unit 201, an input skew correction unit 202, a paper detection time acquisition unit 203, a registration driving amount calculation unit 204, and a registration motor driving unit 205. have.

The input skew calculation unit 201 calculates the amount of inclination (inclined line) of the paper 17 with respect to the conveying direction and the amount of inclination of the paper 17 based on the detection results of the edges in the width direction of the paper 17 by the first edge sensor 26a and the second edge sensor 26b. Calculate the "input skew" including the amount of displacement (horizontal displacement) in the width direction. The input skew indicates the amount of positional deviation (positional deviation amount) with respect to the transport direction of the paper 17 . That is, the input skew calculator 201 corresponds to a positional deviation amount calculator that calculates the amount of positional deviation of the paper 17 in the transport direction.

Based on the input skew calculated by the input skew calculation unit 201, the input skew correction unit 202 calculates the tilt correction amount and the lateral shift correction for correcting the positional shift of the paper 17 (correcting the tilt and lateral shift of the paper). Calculate the quantity. Based on the tilt correction amount and the lateral shift correction amount, the "operation" for correcting the positional shift of the paper 17 in the conveying direction is controlled. It should be noted that the "operation for correcting the positional deviation" means the "rotational operation for correcting the inclination of the paper 17 with respect to the conveying direction" and the "correct position in the width direction of the paper 17 with respect to the conveying direction" in the registration roller mechanism 22. It is an operation including "shift operation for moving to That is, the input skew correction unit 202 operates the rotation mechanism 23 based on the input skew to control the "welcoming operation". Here, the "welcoming operation" is a preparatory operation before executing the correcting operation. This operation includes an operation of moving in a direction that matches the lateral displacement. Further, the input skew correction unit 202 operates the rotation mechanism 23 and the shift mechanism 24 so as to move the registration roller pair 221 in the direction of correcting the input skew. The input skew correction section 202 constitutes position correction means.

The paper detection time acquisition unit 203 acquires the time when the transport sensor 222 detects the paper 17 and notifies the registration driving amount calculation unit 204 of the time.

The registration drive amount calculation unit 204 calculates the drive amount of the registration roller pair 221 based on the input skew calculated by the input skew calculation unit 201 and the time notified from the sheet detection time acquisition unit 203 . The driving amount calculated by the registration driving amount calculation unit 204 includes the time for operating the registration driving motor 223, the operation speed of the registration driving motor 223, and the time required for the registration driving motor 223 to operate again after it stops for a predetermined operation time. time, etc., is calculated as The registration driving amount calculation unit 204 corresponds to driving amount calculation means. The operating speed of the registration drive motor 223 can also be calculated as the number of rotations of the registration roller pair 221 per unit time.

The registration motor drive unit 205 operates the registration drive motor 223 based on the drive amount calculated by the registration drive amount calculation unit 204 to control the conveying operation of the registration roller pair 221 . For example, the operation of the registration drive motor 223 is started at the timing when the transport sensor 222 detects the paper 17, and the operation of the registration drive motor 223 is continued until the operation time corresponding to the drive amount elapses. Further, the registration motor driving unit 205 specifies the operation time of the registration driving motor 223 corresponding to the driving amount from the timing when the transport sensor 222 detects the sheet 17 . The registration drive motor 223 is operated after the sheet 17 reaches the registration roller pair 221 for this operation time. With the control described above, the registration device 200 can keep the stop position where the paper 17 is conveyed and stopped by the pair of registration rollers 221 constant regardless of the magnitude of the input skew of the paper 17 . The registration motor drive unit 205 corresponds to drive control means.

[First embodiment of the transport method according to the present invention]
Next, the operation flow of the registration device 200 according to this embodiment will be described with reference to the flowchart of FIG. 5 and FIGS. 6 to 11. FIG. 6 to 11 illustrate step by step how the paper 17 is conveyed by the registration device 200. FIG. (a) of each figure is a plan view, and (b) is a side view.

First, as shown in FIG. 6 , the paper 17 drawn out from the paper feed tray 12 is transported along the transport path 16 and reaches the transport roller pair 20 . The conveying roller pair 20 pinches the paper 17 and moves it in the conveying direction. The paper 17 is conveyed in the direction of arrow A in FIG. While being conveyed, the first edge sensor 26a and the second edge sensor 26b arranged on the conveying path 16 detect the edges of the paper 17 in the width direction. Based on this detection result, the input skew calculator 201 calculates the input skew (S501).

Next, as shown in FIG. 7, based on the input skew, the input skew correction unit 202 operates the rotation mechanism 23 for rotating the registration roller mechanism 22, and operates the shift mechanism 24 for shifting. to start the "meeting operation" (S502). The pick-up operation is an operation for correcting the positional deviation of the paper 17 and includes a "rotation operation" and a "shift operation". Here, the rotating operation is an operation of inclining the registration roller pair 221 so as to be parallel to the leading edge of the paper 17 . The shift operation is an operation of moving the registration roller pair 221 in the width direction of the paper 17 by an amount corresponding to the amount of lateral displacement of the paper 17 .

Thereafter, as shown in FIG. 8, the paper 17 is further conveyed by the conveying roller pair 20, and when the leading edge thereof reaches the registration roller mechanism 22, the conveying sensor 222 detects the leading edge of the paper 17 (S503/YES). When the paper 17 reaches the registration roller pair 221 , the conveying roller pair 20 is separated to release the paper 17 . On the other hand, the registration roller pair 221 nips the paper 17, and the registration motor drive unit 205 drives the registration drive motor 223 to start the transport operation of moving the paper 17 in the transport direction.

Subsequently, the registration drive amount calculation unit 204 calculates the "advance/delay amount" of the sheet 17 of the registration roller pair 221 based on the input skew calculated in S501 and the timing at which the conveyance sensor 222 detects the sheet 17 in S503. It is calculated as a driving amount (S504). Subsequently, the registration motor drive unit 205 drives the registration drive motor 223 based on the calculated drive amount (S505). The operation of the registration drive motor 223 continues until the timing when the operation of the registration drive motor 223 based on the drive amount ends (S506/NO), and the conveying operation by the pair of registration rollers 221 continues.

If it is time to end the conveying operation (S506/YES), then, as shown in FIG. 9, the registration roller pair 221 nips the sheet 17 and starts the correcting operation (S507). The correction operation is an operation to return the registration roller pair 221 to the home position.

As shown in FIG. 10, when the correction operation is completed (S508/YES), the paper 17 has reached the stop position where it is temporarily stopped in preparation for the secondary transfer. At this stage, the skew of the paper 17 has been corrected and the transport roller pair 20 is separated. The transport roller pair 20 abuts against the sheet 17 in preparation for the next transport.

Next, as shown in FIG. 11, the paper 17 whose misalignment has been corrected is conveyed to the secondary transfer section (transfer roller 10). However, while being transported to the secondary transfer portion by the registration roller mechanism 22, the paper 17 may be misaligned again in the transport direction. Therefore, based on the result of detection of the sheet 17 by the third edge sensor 26c arranged on the downstream side of the registration roller mechanism 22 and the second edge sensor 26b arranged on the upstream side of the registration roller mechanism 22, , the inclination of the paper 17 and the amount of lateral displacement are calculated again. Based on this calculation result, the registration roller mechanism 22 is rotated and shifted to perform the operation of correcting again. This corrects the positional deviation again. After that, by repeating the above operation, the sheet 17 whose inclination and lateral deviation have been corrected with high accuracy is delivered from the transport path.

[Timing of Input Skew Correction Operation of Registration Apparatus 200]
Next, the operation of the registration device 200 according to this embodiment described above will be described in detail using timing charts. 12A and 12B are timing charts for explaining the basic transport operation of the registration device 200. FIG. Time T1 is the moment when the transport sensor 222 detects the paper 17 . That is, the sheet detection time acquisition unit 203 notifies the registration driving amount calculation unit 204 of this detection timing.

When the transport sensor 222 detects the paper 17, the registration motor drive unit 205 is driven until a predetermined time thereafter. Here, the predetermined time is assumed to be time T3 shown in FIG. That is, the registration drive motor 223 is basically operated from time T1 to time T3. A driving motor for the registration roller pair 221 is, for example, a stepping motor.

On the other hand, after the paper 17 is detected by the transport sensor 222 (time T1), the paper 17 does not reach the registration roller pair 221 until a short time has passed. This is because the transport sensor 222 is arranged upstream of the registration roller pair 221 in the transport direction. Time T2 indicates the timing at which the paper 17 reaches the registration roller pair 221 and the conveyance of the paper 17 by the registration roller pair 221 is started. Therefore, the sheet 17 is actually conveyed by the pair of registration rollers 221 from time T2 to time T3. At time T3, the operation of the registration drive motor 223 is stopped. Therefore, the time T1 corresponds to the operation start time, and the time T3 corresponds to the operation stop time.

As already described, in the registration device 200 according to the present embodiment, the registration roller mechanism 22 performs a pick-up operation for correcting the inclination and lateral displacement of the paper 17 before the transport sensor 222 detects the paper 17. . Therefore, the conveying sensor 222 detects the paper 17 in a state in which the registration roller mechanism 22 is tilted with respect to the conveying direction or is moving in a direction perpendicular to the conveying direction (width direction) due to the pick-up operation. . Since the transport sensor 222 is installed in the registration roller mechanism 22, the pair of registration rollers is detected at the timing when the transport sensor 222, whose position relative to the paper 17 is changed by the pick-up operation, detects the leading edge of the paper 17 in the transport direction. 221 is controlled. By changing the relative position of the transport sensor 222 to the paper 17, the paper 17 reaches the registration roller pair 221 even if the time for the registration roller pair 221 to operate after the transport sensor 222 detects the paper 17 is constant. The timing to do so depends on the amount of pick-up motion. As described above, the detection timing of the sheet 17 by the transport sensor 222 changes due to the pickup operation for eliminating the input skew. The position varies depending on the magnitude of the input skew.

Therefore, the registration roller mechanism 22 according to the present embodiment performs the processing described with reference to FIG. This will be explained using the timing chart of FIG. At time T1, the transport sensor 222 detects the sheet 17, and the registration motor driving section 205 operates the registration driving motor 223. FIG. At this time, the size of the pick-up operation of the registration roller pair 221 differs depending on the size of the input skew of the paper 17 . If the movement of the registration roller pair 221 due to the welcoming operation is in the direction of approaching the paper 17, the paper 17 reaches the registration roller pair 221 at time T2a earlier than time T2 shown in FIG. The registration drive motor 223 is driven from time T1 to time T3. Therefore, when the paper 17 reaches the registration roller pair 221 at time T2a, which is earlier than time T2, the amount by which the paper 17 is conveyed by the conveyance operation of the registration roller pair 221 becomes "conveyance advance", which is more advanced than usual. On the other hand, when the movement of the registration roller pair 221 due to the welcome operation is in the direction away from the paper 17, the paper 17 reaches the registration roller pair 221 at time T2b later than time T2 shown in FIG. In this case, the amount by which the sheet 17 is conveyed by the operation of the pair of registration rollers 221 is "conveyance delay", which is delayed from normal.

That is, the amount of the transport operation for transporting the paper 17 by the pair of registration rollers 221 differs depending on the magnitude and direction of the inclination of the paper 17 with respect to the transport direction and the amount and direction of the lateral deviation represented by the input skew. If the paper 17 is "advanced" in accordance with the magnitude of the input skew, the stop position of the paper 17 will be downstream of the ideal stop position in the transport direction. Further, when a "transportation delay" occurs, the stop position of the paper 17 becomes upstream in the transport direction from the ideal position.

The registration device 200 according to the present embodiment has a function of eliminating variations in stop positions, which are "advance in transport" or "delay in transport" caused by input skew of the paper 17 . FIG. 14 is a diagram for explaining an outline of control in the registration device 200. As shown in FIG. As shown in FIG. 14, after the transport sensor 222 detects the sheet 17, the registration drive motor 223 is driven to vary the stop time based on the input skew. Specifically, when the registration roller pair 221 moves closer to the sheet 17 in the welcome operation, the driving stop time of the registration drive motor 223 is set to time T3a, which is earlier than normal time T3. In this case, the conveying operation by the registration roller pair 221 is performed from time T2 to time T3a. That is, the time required for the transport operation is shorter than in the ideal transport state (where the input skew is zero).

Further, when the registration roller pair 221 moves away from the sheet 17 in the welcoming operation, the driving stop time of the registration drive motor 223 is set to time T3b, which is later than the normal time T3. In this case, the conveying operation by the registration roller pair 221 is performed from time T2 to time T3b. That is, the transport operation takes longer than in an ideal transport state (when the input skew is zero).

Here, the relationship between the input skew and the time required for the transport operation of the pair of registration rollers 221 to transport the paper 17 will be described. The magnitude of the input skew, the time (T) for the registration roller pair 221 to start and stop the operation, and the time (t) for the paper 17 to reach the registration roller pair 221 after the registration roller pair 221 starts operating. ) is represented by the following equation (1). Note that “Lsens” in Equation (1) is the distance between the center of rotation when the registration roller pair 221 rotates and the installation position of the transport sensor 222 . In this case, the center of rotation is assumed to be the end of the registration roller pair 221 in the width direction, and the transport sensor 222 moves along an arc-shaped trajectory as the registration roller pair 221 rotates.

As shown in Equation 1, the direction of pick-up motion due to input skew can be represented by the sign of Skew.

The operation of the registration device 200 according to this embodiment is not limited to the above example. Another embodiment will be described with reference to FIG. Assume that the transport sensor 222 detects the paper 17 at time T1. In calculating the drive amount based on the direction of the welcoming operation and the magnitude of the welcoming operation of the registration roller pair 221, the operation start timing of the registration drive motor 223 may be variable.

For example, when the registration roller pair 221 moves toward the paper 17 in the pick-up operation, the registration driving motor 223 starts operating at time T1a before the transport sensor 222 detects the paper 17, and the operation time is fixed. do. In this case, the registration drive motor 223 operates from time T1a to time T3c. Then, the conveying operation by the registration roller pair 221 is performed from time T2 to time T3c. Further, when the registration roller pair 221 moves away from the paper 17 in the welcome operation, the driving start time of the registration drive motor 223 is set to time T1b later than time T1, and then driven for a predetermined time. In this case, the registration drive motor 223 operates from time T1b to time T3d. Then, the conveying operation by the registration roller pair 221 is performed from time T2 to time T3d.

As described above, according to the registration device 200 according to the present embodiment, even if the timing at which the paper 17 reaches the registration roller pair 221 after the transport sensor 222 detects the paper 17 changes according to the input skew, The stop position of the paper 17 can be made constant. In other words, the stopping position at which the paper 17 is stopped by the registration roller mechanism 22 is made constant by making the conveying operation of the pair of registration rollers 221 to convey the paper 17 constant. As a result, it is possible to prevent "conveyance advance" or "conveyance delay", which is variation in the stop position of the paper 17 after the input skew correction operation, and accurately match the transfer position of the image in the secondary transfer section. can.

[Second embodiment of the transport method according to the present invention]
Next, the operation flow of the registration device 200 according to this embodiment will be described using the flowchart of FIG. First, S501 to S504 and S506 to S508 in the first embodiment of the conveying method already explained are the same processes as S1601 to S1604 and S1606 to S1608 according to the present embodiment, so detailed explanation is omitted. Here, S1605, which is different from the first embodiment, will be mainly described.

First, while the sheet 17 is being conveyed toward the registration roller mechanism 22, the first edge sensor 26a and the second edge sensor 26b detect the edges of the sheet 17 in the width direction, and the input skew calculation unit 201 calculates the input skew. (S1601). Then, based on the calculated input skew, the input skew correction unit 202 starts the "welcoming operation" of the registration roller mechanism 22 (S1602). After that, when the leading edge of the paper 17 reaches the registration roller mechanism 22 and the transport sensor 222 detects the leading edge of the paper 17 (S1603/YES), the registration drive amount calculation unit 204 determines the “advance/delay amount” of the paper 17. Using the driving amount calculated based on the above, the driving amount of the registration roller pair 221 is calculated (S1604). The drive amount calculated in S1604 is calculated based on the input skew calculated in S1601 and the timing at which the transport sensor 222 detects the paper 17 in S1603.

Subsequently, the registration motor driving unit 205 drives the registration driving motor 223 based on the calculated driving amount (S1605). In S1605, the rotational speed of the registration drive motor 223 is controlled.

S1605 will be described in detail. After the registration roller mechanism 22 starts the welcoming operation (S1602) (S1602), at the timing when the conveyance sensor 222 detects the paper 17 (S1603/YES), the registration roller mechanism 22 conveys the paper 17 to the stop position where it stops. Calculate the amount of deviation of In order to eliminate this amount of deviation, the amount by which the conveying speed of the paper 17 is changed is calculated to calculate the target conveying speed. The control unit of the registration roller mechanism 22 stores the transport speed of the paper 17 in an ideal transport state with no input skew. Therefore, in S1605, the rotation speed of the registration roller pair 221 is calculated based on the calculated input skew and the previously stored transport speed.

An overview of the speed control in S1605 will be described with reference to FIGS. 17 to 19. FIG. It is assumed that FIG. 17 shows the normal conveying speed Vs pre-stored in the control section of the registration roller mechanism 22 . It is assumed that the controller stores control data for controlling the rotation speed of the registration roller pair 221 for conveying the sheet 17 at the conveying speed Vs. Here, the control unit also stores data for controlling the amount of change in the rotation speed of the pair of registration rollers 221 for conveying the paper 17 at a conveying speed Vsu higher than the conveying speed Vs and a conveying speed Vsd lower than the conveying speed Vs. It shall be

In S1605, if the timing of reaching the registration roller pair 221 is normal timing T4, the transport speed of the paper 17 by the registration roller pair 221 remains at the normal transport speed Vs.

In S1605, when an input skew occurs such that the arrival at the registration roller pair 221 is at timing T5 earlier than timing T4, that is, when an input skew occurs in the direction in which arrival is earlier than normal , are controlled as shown in FIG. That is, the registration motor drive unit 205 slows down the rotation speed of the registration roller pair 221 and controls the transport speed of the paper 17 to be the transport speed Vsd. As a result, the conveying distance of the paper 17 by the registration roller pair 221 after the paper 17 reaches the registration roller pair 221 can be shortened.

In S1605, when the input skew occurs such that the arrival at the registration roller pair 221 is at the timing T6 later than the timing T4, that is, when the input skew occurs in the direction in which the arrival is later than usual. controls as shown in FIG. That is, the registration motor drive unit 205 increases the rotation speed of the registration roller pair 221 and controls the transport speed of the paper 17 to the transport speed Vsu. As a result, the conveying distance of the paper 17 by the registration roller pair 221 after the paper 17 reaches the registration roller pair 221 can be lengthened.

As described above, by controlling the rotation speed of the registration roller pair 221 and changing the transport speed of the paper 17, the deviation of the stop position where the paper 17 stops due to the transport of the paper 17 by the registration roller pair 221 can be eliminated. can be done.

In S1605, the speed control operation as described above is continued until a preset time. Correction operation for correcting the positional deviation of the paper 17 with respect to the transport direction is started (S1607). After that, when the correction operation is completed (S1608/YES), the conveyance of the paper 17 is temporarily stopped.

As described above, according to the transport method according to the present embodiment, by adjusting the speed of the transport operation of the registration roller pair 221 according to the magnitude of the input skew, the transport amount of the paper 17 by the registration roller pair 221 can be increased. can be made constant. According to the positional deviation amount of the sheet being conveyed, the amount of advancement or delay of the sheet with respect to the reference position can be eliminated.

[Third embodiment of the transport method according to the present invention]
Next, the operation flow of the registration device 200 according to this embodiment will be described with reference to the flowchart of FIG. 20 and the charts shown in FIGS. 21 to 23. FIG. First, S501 to S508 in the first embodiment of the transport method already explained are the same processes as S2001 to S2008 according to the present embodiment, so detailed explanations are omitted. Here, S2009 to S2011, which are different processes from the first embodiment, will be mainly described.

First, while the sheet 17 is being conveyed toward the registration roller mechanism 22, the first edge sensor 26a and the second edge sensor 26b detect the edges of the sheet 17 in the width direction, and the input skew calculation unit 201 calculates the input skew. (S2001). Then, based on the calculated input skew, the input skew correction unit 202 starts the "welcoming operation" of the registration roller mechanism 22 (S2002).

After that, when the leading edge of the paper 17 reaches the registration roller mechanism 22 and the transport sensor 222 detects the leading edge of the paper 17 (S2003/YES), the registration driving amount calculation unit 204 calculates the driving amount of the registration roller pair 221. (S2004). The drive amount calculated in S2004 is based on the input skew calculated in S1601 and the amount of “advance in conveyance” or “delay in conveyance” of the paper 17 calculated based on the timing at which the conveyance sensor 222 detects the paper 17 in S2003. based on

Subsequently, the registration motor driving unit 205 drives the registration driving motor 223 based on the calculated driving amount (S2005). When the timing for completing the conveying operation in S2005 has come (S2006/YES), the pair of registration rollers 221 starts correcting the misalignment of the paper 17 with respect to the conveying direction (S2007). (S2008/YES), the conveyance of the paper 17 is temporarily stopped.

Next, based on the "advance/delay amount" calculated in S2004, the timing for resuming the conveyance of the paper 17 is calculated (S2009). Subsequently, in S2009, it is determined whether or not the calculated restart timing has been reached, and if the restart timing has not been reached (S2010/NO), the processing is looped.

If the restart timing has come (S2010/YES), the driving of the registration drive motor 223 is controlled (S2011), and the conveyance of the paper 17 is restarted.

Here, S2209 to S2011 will be described in detail. By using Equation 1 already explained, it is possible to calculate the input skew of the paper 17 at the stage where the correction operation in S2007 is finished (S2008/YES). After the correcting operation of the paper 17 is completed, the conveying operation of the paper 17 is stopped. Thereafter, the conveying speed of the paper 17 is restarted at the conveying speed Vp based on the transfer timing. The restart timing is calculated based on the "advance/delay amount" calculated in S2004.

For example, as shown in FIG. 21, the restart timing when the paper 17 reaches the registration roller pair 221 at normal timing is assumed to be "T7". In this case, at timing T7, the registration motor driving unit 205 drives the registration driving motor 223 so that the paper 17 is restarted to be conveyed and then conveyed at the conveyance speed Vp.

Based on the "advance/delay amount" calculated in S2004, when the arrival timing of the paper 17 to the registration roller pair 221 is advanced, as shown in FIG. It is assumed that the timing is "T8" which is later than the timing T7. In this case, at timing T8, the registration motor driving unit 205 drives the registration driving motor 223 so that the paper 17 is restarted to be conveyed and then conveyed at the conveyance speed Vp.

Based on the "advance/delay amount" calculated in S2004, when the arrival timing of the paper 17 to the registration roller pair 221 is delayed, as shown in FIG. It is assumed that the timing is "T9" which is earlier than the timing T7. In this case, at timing T9, the registration motor driving unit 205 drives the registration driving motor 223 so that the paper 17 is restarted to be conveyed and then conveyed at the conveyance speed Vp.

Note that the "advance/delay amount" calculated in S2004 is a positive value if it advances relative to the transport direction, and a negative value if it lags relative to the transport direction. Therefore, the restart timing calculated in S2209 has a positive value when it is delayed relative to the normal timing, and a negative value when it is advanced.

As described above, according to the registration device 200 according to the present embodiment, even if the timing at which the paper 17 reaches the registration roller pair 221 after the conveyance sensor 222 detects the paper 17 changes due to the input skew, the transfer timing can be kept constant. As a result, even if the stop position of the paper 17 after the input skew correction operation remains misaligned due to advance or delay in transport, the transfer position of the image in the secondary transfer portion can be aligned with high accuracy.

[Second Embodiment of Image Forming Apparatus]
Although the electrophotographic image forming apparatus 100 has been described as an example of the image forming apparatus according to the present embodiment, the image forming apparatus 100a can be similarly applied to an inkjet image forming apparatus 100a, for example. The overall configuration of the image forming apparatus 100a will be described with reference to FIG.

As shown in FIG. 16 , the inkjet image forming apparatus 100 a includes a paper feeding section 110 , a registration device 200 a , an image forming section 130 , a drying section 140 and a paper discharging section 150 .

A sheet 17 is a sheet-shaped object to be conveyed that is sent out from the paper feeding section 110 that constitutes the storage section. The paper 17 is conveyed by the registration device 200 a and sent to the image forming section 130 .

In the image forming section 130, the paper 17 is positioned on the cylindrical drum 131 and conveyed in the direction of the arrow shown in FIG. 24 as the cylindrical drum 131 rotates. Then, the paper 17 is conveyed at a predetermined timing to the lower part of the liquid ejection head 132 (the image forming position on the paper 17) that ejects the ink liquid of each color, and the ink of each color is ejected onto the paper 17. An image is formed on the surface of 17 .

The paper 17 on which an image has been formed by the image forming section 130 is conveyed to the drying section 140 to evaporate the moisture in the ink, and then is placed at a position where the operator can take it out in the paper discharge section 150 constituting the discharge section. discharged to

When double-sided printing is performed, after the drying process, the paper 17 is sent to the reversing conveying path 160, and the paper 17 is sent to the registration device 200a again in a state in which the front and back of the paper 17 are reversed.

The registration device 200a described above is an embodiment of the transport device according to the present invention and constitutes a transport section. That is, the registration device 200a has functions corresponding to the registration device 200 already described. The registration device 200a corrects "skew" in which the paper 17 is conveyed in a state of being inclined with respect to the conveying direction, and "misalignment in the width direction (horizontal misalignment)", and performs image formation according to the corrected amount. The timing of conveying the paper 17 to the unit 130 is controlled. Then, the paper 17 is conveyed to the downstream image forming section 130 in a state in which the positional deviation of the paper 17 is corrected.

In addition to the paper 17 (plain paper), the sheet-like transported object includes thick paper, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheets, plastic films, Prepreg, copper foil, etc. are included.

The image forming apparatus according to the present invention is not limited to the color image forming apparatus shown in FIGS. 1 and 16, but may be a monochrome image forming apparatus, a copying machine, a printer, a facsimile machine, or a multi-function machine of these.

10: Transfer roller 11: Opposing roller 12: Paper feed tray 14: Fixing roller 16: Conveyance path 17: Paper 20: Conveyance roller pair 22: Registration roller mechanism 23: Rotating mechanism 24: Shift mechanism 26a: First edge sensor 26b : Second edge sensor 26c : Third edge sensor 100 : Image forming apparatus 110 : Paper feeding unit 130 : Image forming unit 131 : Cylindrical drum 132 : Liquid ejection head 134 : Photoreceptor drum 135 : Intermediate transfer belt 140 : Drying unit 150: Paper discharge unit 160: Reverse conveying path 161: Branch unit 162: Reverse path 200: Registration device 201: Input skew calculation unit 202: Input skew correction unit 203: Paper detection time acquisition unit 204: Registration driving amount calculation unit 205: Registration motor driving section 210: Controller 220: Driver 221: Registration roller pair 222: Conveyance sensor 223: Registration drive motor 224: Conveyance drive motor 500: Discharge tray

JP 2016-175776 A

Claims (9)

a nipping roller that nips and conveys the transported object that has been transported and corrects the position of the transported object;
a first sensor arranged upstream of the nipping roller in the conveying direction and detecting the position of the conveyed object;
a second sensor that operates integrally with the nipping roller and detects the object to be conveyed;
a control unit that controls transport driving in the nipping roller based on the position of the transported object detected by the first sensor;
has
The control unit
positional displacement amount calculation means for calculating the positional displacement amount of the transported object based on the detection result of the first sensor;
driving amount calculation means for calculating a driving amount related to the conveying driving of the nipping roller based on the positional deviation amount and the timing at which the second sensor detects the conveyed object;
drive control means for controlling transport drive of the nipping rollers for nipping and transporting the transported object based on the drive amount;
A conveying device comprising: The driving amount calculation means calculates an operation stop time from the timing at which the second sensor detects the conveyed object until the operation of the nipping roller is stopped,
The drive control means drives the nipping roller to convey until the operation stop time.
2. The conveying apparatus of claim 1. The driving amount calculation means calculates an operation start time for starting the operation of the nipping roller from the timing at which the second sensor detects the conveyed object,
The drive control means drives the nipping roller to convey for a predetermined period of time after the operation start time has passed.
2. The conveying apparatus of claim 1. The driving amount calculating means calculates an amount of change in rotational speed of the nipping roller up to a time at which the nipping roller is stopped based on the detection timing of the conveyed object by the second sensor,
The drive control means drives the nipping roller to convey at a rotational speed changed based on the amount of change.
2. The conveying apparatus of claim 1. The driving amount calculating means drives the nipping rollers to convey until an operation stop time from the detection timing of the conveyed object by the second sensor until the operation of the nipping rollers is stopped,
Thereafter, calculating a restart timing for restarting the conveying drive of the nipping roller based on the positional deviation amount,
The drive control means restarts the conveying drive of the nipping roller based on the restart timing.
2. The conveying apparatus of claim 1. The control unit further includes position correction means for controlling correction driving of the nipping roller so as to correct the amount of positional deviation of the conveyed object,
The drive control means controls the correction drive while controlling the transport drive.
6. A conveying device according to any one of claims 1 to 5. A third sensor arranged downstream of the nipping roller in the conveying direction and detecting the position of the conveyed object,
After controlling the correction drive, the drive control means performs correction drive for correcting the positional deviation of the conveyed object again based on the detection of the third sensor.
7. The conveying device according to claim 6 . an image forming unit that forms an image on a conveyed object;
a transport unit that transports the transported object from the transported object storage unit to the image forming unit;
a discharge unit for discharging the conveyed object on which the image is formed;
with
The transport unit is the transport device according to any one of claims 1 to 7,
An image forming apparatus characterized by: A conveying method in a conveying device provided with nipping rollers for nipping and conveying a conveyed object and correcting the position of the conveyed object, comprising:
calculating the amount of positional deviation of the conveyed object detected by a first sensor arranged upstream of the nipping roller in the conveying direction;
A driving amount of the nipping roller is calculated based on the amount of positional deviation and a detection timing at which a second sensor that operates integrally with the nipping roller detects the conveyed object, and based on the driving amount, the to control the transport drive of the nipping roller,
A conveying method characterized by:

Images