JP7017118B2 - Conveyor device and image forming device - Google Patents

Description

The present invention relates to a transport device for transporting a sheet, and an image forming apparatus such as a copying machine, a printer, a facsimile, a multifunction device thereof, or an offset printing machine equipped with the transport device.

Conventionally, in an image forming apparatus such as a copying machine or a printer, the skew amount in the tilting direction of a sheet transported in a predetermined transport direction (the direction tilted with respect to the transport direction in the sheet transport surface) is detected. Then, a technique for correcting the skew (tilt) of the sheet based on the detection result is known (see, for example, Patent Document 1).

Specifically, the transport device in Patent Document 1 is provided with a pair of holding rollers configured to be rotatable in the tilt direction. Further, in the transport device, a plurality of CIS (contact image sensors) for detecting the position in the width direction of the sheet transported in a predetermined direction are arranged side by side at positions separated from each other in the transport direction. Then, when the sheet passes through the position of CIS, the skew amount of the sheet is detected by CIS, and the sandwiching roller pair is rotated from the reference position so as to face the sheet corresponding to the skew amount. Then, when the sheet reaches the position of the pinching roller pair and is pinched and conveyed by the pinching roller pair, the seat is rotated so as to return the pinching roller pair to the reference position to correct the skew of the seat. ..

In the conventional transfer device described above, the reference position of the pinching roller pair deviates from the target position due to the assembly error of various components such as the pinching roller pair and the component error, and the sheet skews due to the pinching roller pair. There was a possibility that the correction would not be performed with high accuracy.

The present invention has been made to solve the above-mentioned problems, and provides a transport device and an image forming device capable of performing skew correction of a sheet transported in a predetermined transport direction with high accuracy. To do.

The transport device in the present invention is a transport device that transports a sheet in a transport path, and is rotationally driven by a detecting means for detecting the position of an end face in the width direction of the sheet transported in the transport path and a first drive means. , The sheet is conveyed while being sandwiched between the nip portions, and is conveyed to the first roller pair and the first roller pair, which are configured to be rotatable in a direction parallel to the sheet transfer surface by the second drive means. The second roller pair, which is arranged on the downstream side in the direction or the upstream side in the transport direction and transports the sheet together with the first roller pair in a state of being sandwiched between the nip portions, and the first roller pair by the second drive means are transferred to the sheet. The position of the end face in the width direction of the sheet while being rotated by the first roller pair and the second roller pair at each stage by rotating the sheet in a plurality of stages of rotation positions in a direction parallel to the transport surface. The time change is detected by the detection means, and the rate of the time change after the sheet reaches the nip portion of the first roller pair and the time change after the sheet reaches the nip portion of the second roller pair. It is provided with a control unit that sets a rotation position that substantially coincides with the rate of time change of the above as a reference position.

According to the present invention, it is possible to provide a transport device and an image forming device capable of performing skew correction of a sheet transported in a predetermined transport direction with high accuracy.

It is an overall block diagram which shows the image forming apparatus in Embodiment 1 of this invention. It is a schematic diagram which shows the transport device. It is a top view which shows a part of a transporting apparatus. It is a block diagram which shows the main part of the transport device. It is a schematic top view which shows the main part of the transport device. It is a figure which shows the state which the holding member is supported on the frame by the relay support member in a transfer device. It is a block diagram which shows the two-step spline coupling. A diagram in which the holding member operates in the width direction, a diagram in which the holding member operates in the tilt direction, and a diagram in which the holding member operates in the width direction and the tilt direction at the same time. It is a schematic diagram which shows the operation of a transfer device. It is the schematic which shows the operation of the transfer apparatus following FIG. It is a figure which shows the state which the reference position in the inclination direction of a pair of sandwiching rollers is deviated. It is a graph which shows the detection result of 2 CIS for each step when the tilt direction (diagonal direction) of a pinch roller pair is changed in 5 steps. From the detection result of FIG. 11, it is a graph which aggregated the relationship between the inclination angle of a pair of sandwiching rollers and the linearity of the change of the seat end face position. It is a flowchart which shows the control in the reference position adjustment mode. It is a control flow which shows skew correction and lateral resist correction. It is a block diagram which shows the control part. It is a figure which shows the operation of the holding roller pair in the reference position adjustment mode. It is an overall block diagram which shows the image forming apparatus in Embodiment 2 of this invention. It is an overall block diagram which shows the image forming apparatus in Embodiment 3 of this invention.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In each figure, the same or corresponding parts are designated by the same reference numerals, and the duplicated description thereof will be appropriately simplified or omitted.

<Embodiment 1>
First, FIG. 1 describes the overall configuration and operation of the image forming apparatus.
In FIG. 1, 1 is a copying machine as an image forming apparatus, 2 is a document reading unit that optically reads image information of a document D, and 3 is a photoconductor that emits exposure light L based on the image information read by the document reading unit 2. The exposure unit 4 that irradiates the drum 5 indicates an image forming unit that forms a toner image (image) on the photoconductor drum 5.
Further, 7 is a transfer roller that transfers the toner image formed on the photoconductor drum 5 to the sheet P, 10 is a document transport section that transports the set document D to the document reading section 2, and 12 to 14 are transfer papers and the like. A paper feed unit (paper cassette) in which the sheet P is housed, 20 is a fixing device for fixing an unfixed image on the sheet P, 21 is a fixing roller installed in the fixing device 20, and 22 is installed in the fixing device 20. Pressurized roller, which is shown.
Further, 30 is a transport device that transports the sheet P along the transport path, and 31 is a first roller pair that functions as a resist roller (timing roller) that transports the sheet P toward the transfer roller 7 (transfer nip portion). A pair of sandwiching rollers (horizontal resist / skew correction roller) is shown.

With reference to FIG. 1, an operation during normal image formation in an image forming apparatus will be described.
First, the document D is conveyed from the document table in the direction of the arrow in the drawing by the transfer roller of the document transfer unit 10, and passes over the document reading unit 2. At this time, the document reading unit 2 optically reads the image information of the document D passing above.
Then, the optical image information read by the document reading unit 2 is converted into an electric signal and then transmitted to the exposure unit 3 (writing unit). Then, the exposure light L (laser light) based on the image information of the electric signal is emitted from the exposure unit 3 toward the photoconductor drum 5 of the image forming unit 4.

On the other hand, in the image forming unit 4, the photoconductor drum 5 is rotated in the clockwise direction in the drawing, and the image information is displayed on the photoconductor drum 5 through a predetermined image forming process (charging step, exposure step, developing step). An image (toner image) corresponding to the above is formed.
After that, the image formed on the photoconductor drum 5 is transferred at the position of the transfer roller 7 onto the sheet P conveyed by the sandwiching roller pair 31 (first roller pair) that functions as a resist roller.

On the other hand, with reference to FIGS. 1 and 2, the sheet P conveyed to the transfer roller 7 (image forming unit) operates as follows.
First, one of the paper feed units 12 to 14 of the image forming apparatus main body 1 is automatically or manually selected (for example, the paper feed unit 12 built in the device main body 1 is selected. It shall be.).
Then, the uppermost sheet of the sheet P housed in the paper feed unit 12 is supplied by the paper feed roller 41 toward the curved transport path in which the first transport roller pair 42 and the second transport roller pair 43 are installed. Will be sent.

After that, the sheet P passes through the position of the merging portion X (the portion where the transport paths from the two paper feed portions 13 and 14 installed outside the apparatus main body 1 merge) from the curved transport path, and then passes through the position. The third transfer roller pair 44 (upstream transfer roller pair) and the matching portion 51 pass through the straight transfer path installed and reach the position of the holding roller pair 31 constituting the matching portion 51. Then, skew correction (skew correction) and lateral resist correction are performed by the sandwiching roller pair 31 constituting the matching portion 51, and the timing is adjusted to align with the image formed on the photoconductor drum 5. Is conveyed toward the transfer nip portion (the portion where the transfer roller 7 and the photoconductor drum 5 come into contact with each other). The transfer roller 7 and the photoconductor drum 5 rotate along the transport direction indicated by the arrow, respectively. The transfer roller 7 and the photoconductor drum 5 are arranged on the downstream side in the transport direction with respect to the sandwiching roller pair 31, and the sheet P is nipped together with the sandwiching roller pair 30 (first roller pair) (transfer nip portion). It also functions as a second roller pair (downstream side transport roller pair) for transporting while being sandwiched between the two.

Then, the sheet P after the transfer step reaches the fixing device 20 via the transport path after passing through the position of the transfer roller 7. The sheet P that has reached the fixing device 20 is sent between the fixing roller 21 and the pressure roller 22, and the image is fixed by the heat received from the fixing roller 21 and the pressure received from both members 21 and 22. .. The sheet P on which the image is fixed is discharged from between the fixing roller 21 and the pressure roller 22 (which is the fixing nip portion), and then discharged from the image forming apparatus main body 1.
In this way, a series of image forming processes is completed.

Here, referring to FIG. 2, the image forming apparatus 1 in the first embodiment can feed the sheet P from the three paper feeding units 12 to 14 toward the transfer roller 7 (transfer nip unit). It is configured.
Further, the transport roller pairs 42 to 44 (including unmarked transport roller pairs) installed in the transport device 30 are all a drive roller (a roller that is rotationally driven by a drive mechanism). It is a roller pair composed of a driven roller (a roller that is driven and rotated by frictional resistance with a driving roller), and is configured to be able to convey the seat P while being sandwiched between the two rollers.

Here, from the confluence X where the transfer path from the first paper feed section 12 and the transfer path from the second and third paper feed sections 13 and 14 merge, the transfer roller 7 (transfer nip section) As a transport path up to, a linear transport path formed substantially linearly along the transport direction of the sheet P is provided. This linear transport path is formed by a straight transport guide plate (installed so as to sandwich the front and back surfaces of the sheet P to be transported), and is a third pair of upstream transport rollers along the transport direction. A transport roller pair 44, two CIS as detection means (first CIS35 and second CIS36), and a sandwiching roller pair 31 (matching portion 51) are installed. The third transfer roller pair 44 and the sandwiching roller pair 31 are both roller pairs composed of a driving roller and a driven roller, and transfer the sheet P while sandwiching it between the two rollers. Then, the sandwiching roller pair 31 performs a matching operation of skew correction (correction for the positional deviation in the tilt direction with respect to the transport direction) and lateral resist correction (correction for the positional deviation in the width direction). It will also function as the matching unit 51 of the above, which will be described in detail later.

Next, the transport device 30 according to the first embodiment will be described in more detail with reference to FIGS. 2 to 10.
Hereinafter, the configuration in the transport path from the confluence portion X to the transfer roller 7 (image forming portion) and the operation performed therefor will be mainly described.
With reference to FIGS. 2 and 3, the transfer device 30 is provided with a third transfer roller pair 44 (upstream) along a linear transfer path of the sheet P (a transfer path from the merging portion X to the transfer roller 7). A pair of side transfer rollers), CIS35, 36 (contact image sensor), and a sandwiching roller pair 31 (horizontal resist skew correction roller) that functions as a matching portion 51 and also as a resist roller are installed.

Here, the sandwiching roller pair 31 as the first roller pair is rotationally driven by the first motor 61 as the first driving means, and conveys the seat P in a state of being sandwiched between the nip portions, and the second driving means 63. , 81-84, 98 are configured to be rotatable in a direction parallel to the sheet transport surface (hereinafter, appropriately referred to as "tilt direction").

Specifically, the sandwiching roller pair 31 is a roller pair having a plurality of roller portions divided in the width direction, and is driven to be rotationally driven by a first motor 61 (see FIG. 4) as the first driving means. It is composed of a roller 31b and a driven roller 31a that rotates in accordance with the rotation of the driving roller 31b. The sandwiching roller pair 31 is formed so that the sheet P can be conveyed by rotating the sheet P while sandwiching the sheet P.
In the first embodiment, as the sandwiching roller pair 31, a roller pair having a plurality of roller portions divided in the width direction is used, but the holding roller pair has a roller portion extending in the width direction without being divided in the width direction. Roller pairs can also be used.

Further, the sandwiching roller pair 31 is formed together with the holding frame 72 as a holding member so as to be rotatable about a support shaft 73 in an inclined direction (in the direction of the broken double arrow W in FIG. 3) and has a width. It is formed so that it can move in a direction (in the direction of the broken line arrow S in FIG. 3).
Then, the sandwiching roller pair 31 moves along the guide portion 71a together with the holding frame 72 based on the detection result of the first CIS35 (or the second CIS36) that functions as the detection means (first detection means), and is lateral to the sheet P. The resist is corrected, and the skew of the sheet P is corrected by rotating around the support shaft 73 together with the holding frame 72 based on the detection results of the CIS 35 and 36 which also function as the second detection means.

More specifically, with reference to FIGS. 4 to 6, the sandwiching roller pair 31 (driven roller 31a and driving roller 31b) is rotatably supported by the holding frame 72 as a holding portion. The holding frame 72 (holding portion) is formed by forming a sheet metal in a substantially box shape, and both ends in the width direction (the direction perpendicular to the paper surface of FIG. 2 and the left-right direction of FIGS. 4 to 6). The shaft portion of the sandwiching roller pair 31 (driven roller 31a and drive roller 31b) is inserted into the hole formed in the portion via a bearing. The holding frame 72 moves in the width direction and rotates about the support shaft 73 together with the holding roller pair 31.
On one end side of the drive roller 31b in the width direction, it is fixedly installed to the bracket 69 in the frame of the transport device 30 (the main body frame 70, the base frame 71, the bracket 69 and the like are fixed by screwing). A first driving means (composed of a first motor 61, gear trains 66, 67, etc.) is connected via a two-stage spline coupling 65. As a result, the rotational driving force of the first motor 61 fixed to the frames 69 to 71 of the transport device 30 is transmitted to the drive roller 31b via the gear trains 66, 67 and the two-stage spline coupling 65, and the pinching roller pair. 31 will be rotationally driven.
Further, on the other end side of the drive roller 31b in the width direction, an encoder 96 for controlling the rotation speed, rotation timing, etc. of the sandwiching roller pair 31 (drive roller 31b) is installed.

Here, as shown in FIG. 7, the two-stage spline coupling 65 includes a first spline gear 65a, a second spline gear 65b, an intermediate spline gear 65c, a guide ring 65d, and the like.
The first spline gear 65a is an external gear and is rotatably held by a rotary shaft 68 (a bracket 69 via a bearing) that rotates together with one of the gear rows 66 and 67 of the first drive means. .) Is installed.
The second spline gear 65b is an external gear and is installed on the shaft portion of the drive roller 31b of the sandwiching roller pair 31.
The intermediate spline gear 65c is an internal gear, and extends in the width direction so that the holding roller pair 31 (holding frame 72) meshes with the two spline gears 65a and 65b even if the holding roller pair 31 (holding frame 72) moves in the width direction (slide movement). It is set up. Further, the two spline gears 65a and 65b are formed in a crown shape so as to mesh with the intermediate spline gear 65c even if the sandwiching roller pair 31 (holding frame 72) rotates in the tilting direction (diagonal direction). ..
By using such a two-stage spline coupling 65, even if the sandwiching roller pair 31 rotates around the support shaft 73 in the substantially horizontal plane direction or slides in the width direction, the frame 69 to the main body The driving force of the first motor 61 (first driving means) fixedly installed on the 71 is accurately and surely transmitted to the sandwiching roller pair 31 (driving roller 31b), and the sandwiching roller pair 31 is satisfactorily driven to rotate. Will be done.
The guide ring 65d is a substantially annular stopper member, and is intermediate in order to prevent the two spline gears 65a and 65b from moving relatively in the width direction and falling off from the two-stage spline coupling 65. The spline gears 65c are installed at both ends in the width direction.

Here, referring to FIGS. 5 and 6, the holding frame 72 (holding member) is a free bearing 95 (ball transfer) as a relay support member installed in the frames 69 to 71 (base frame 71) of the apparatus. The bearings are movably supported in both the width direction and the tilt direction with respect to the frames 69 to 71 (base frame 71) (so that the plane orthogonal to the paper surface of FIG. 6 can be freely moved). It is supported). In FIG. 4, the free bearing 95 is not shown in order to make it easier to see other components.
Here, the free bearing 95 (ball transfer) is a known one in which a steel ball 95a (sphere) is inserted in a recess of the pedestal 95b, and the top of the steel ball 95a makes point contact with the bottom surface of the holding frame 72. It will be. Three or more free bearings 95 as relay support members are arranged so as to support the holding frame 72 at three or more locations with respect to the frames 69 to 71 (base frame 71) (the present embodiment). In 1, four free bearings 95 are installed.). In the first embodiment, as shown in FIG. 5, at positions corresponding to the four corners on the bottom surface of the holding frame 72 (positions that can be contacted even if the holding frame 72 slides or rotates to the maximum). Each of the free bearings 95 is fixedly installed on the base frame 71.
By supporting the holding frame 72 with respect to the base frame 71 via the free bearing 95 in this way, even if the holding frame 72 moves relative to the base frame 71 in the plane direction, the friction caused by the movement is caused. Since the load can be made extremely small, the lateral resist correction and skew correction (skew correction) described later can be performed with good responsiveness and high accuracy.

Here, with reference to FIGS. 4, 5 and the like, the holding frame 72 (holding member) is fitted with a guide portion 71a formed so as to extend in the width direction in the base frame 71 (frame of the main body). A support shaft 73 (stud) is provided.
Specifically, on the bottom surface of the holding frame 72, a support shaft 73 (stud) stands up at a position relatively close to the end of the drive side (right side of FIGS. 4 and 5) so as to stand downward. Is fixed and installed by caulking. On the other hand, on the ceiling surface of the base frame 71, a guide portion 71a (a substantially rectangular hole portion) is located at a position relatively close to the end portion on the drive side (right side of FIGS. 4 and 5). Is formed. Then, the support shaft 73 of the holding frame 72 is fitted into the guide portion 71a (hole portion) of the base frame 71 via the guide roller 76 (a roller-shaped member rotatably installed on the support shaft 73). It is formed to do. Then, the holding frame 72, together with the holding roller pair 31, slides in the width direction in conjunction with the movement of the support shaft 73 along the guide portion 71a, or rotates around the support shaft 73. ..
In the first embodiment, the guide portion 71a to which the support shaft 73 of the holding frame 72 fits is a substantially shaped hole portion, but the guide portion 71a enables the operation of the holding frame 72 described above. If there is, the guide portion 71a can be formed into a substantially elongated hole shape, or the guide portion 71a can be a groove portion, without limitation.

With such a configuration, the holding frame is based on the detection results of the two CIS35, 36 (second detection means) by the second drive means 63, 81 to 84, 98 installed on the base frame 71 (frame of the main body). By rotating 72 around the support shaft 73, the holding roller pair 31 is rotated in the tilting direction together with the holding frame 72.
Further, the support shaft 73 is guided by the third drive means 62, 74, 97 installed on the base frame 71 (frame of the main body) based on the detection result of the first CIS35 (or the second CIS36) as the detection means. By moving along, the sandwiching roller pair 31 is moved in the width direction together with the holding frame 72.

Specifically, the second drive means is for rotating the holding frame 72 (pinching roller pair 31) around the support shaft 73, and is the second motor 63, the timing belt 98, the first cam 84, and the first. 1. It is composed of a first tension spring 92 as an urging member, a lever member 81 (rotary lever), and the like.
The first tension spring 92 as the first urging member urges the holding frame 72 in the positive direction in the tilt direction (clockwise with respect to the support shaft 73 in FIG. 5) so that the holding frame 72 is urged. And the base frame 71.
The first cam 84 is rotatably held by the base frame 71 about the rotation support shaft 84a, and the holding frame 72 urged in the positive direction in the tilt direction by the first tension spring 92 is held in the direction opposite to the tilt direction. (It is a counterclockwise direction about the support shaft 73 in FIG. 5) and is indirectly pushed via the lever member 81. That is, the second driving means is configured to push the holding frame 72 via the lever member 81.
The lever member 81 is rotatably held by the base frame 71 about a rotary support shaft 81a, and a cam follower 82 (first roller-shaped member) abutting on the first cam 84 is rotatably installed on one end side thereof. (Shaft support), and an action roller 83 (second roller-shaped member) that abuts on the protrusion 72a of the holding frame 72 is rotatably installed (shaft support) on the other end side.
The second motor 63 is fixedly installed on the base frame 71. A timing belt 98 is wound around the drive pulley installed on the motor shaft of the second motor 63 and the driven pulley installed on the rotary support shaft 84a of the first cam 84.

With such a configuration, referring to FIG. 8B, when the second motor 63 is driven, the rotational driving force thereof is transmitted to the first cam 84 via the timing belt 98, and the lever member 81 is moved. By being pushed by the first cam 84 and rotating around the rotary support shaft 81a, the holding frame 72 is pushed by the lever member 81 at the position of the protrusion 72a, and the spring force of the first tension spring 92 is applied. The holding frame 72 will rotate to resist.

Due to the spring force of the first tension spring 92, the first cam 84 and the lever member 81 (cam follower 82) are always in contact with each other, and the holding frame 72 (projection portion 72a) and the lever member 81 (protruding portion 72a) are in contact with each other. It is always in contact with the action roller 83), and depending on the rotation angle (rotational posture) of the first cam 84, the rotation angle (rotational posture) of the holding frame 72 around the support shaft 73. Will be determined.
In this way, the cam follower 82 as the first roller-shaped member is installed at the contact position between the first cam 84 and the lever member 81, and at the contact position between the holding frame 72 (projection portion 72a) and the lever member 81. By installing the action roller 83 as the second roller-shaped member, the frictional load generated at each contact position can be made extremely small, so that skew correction (skew correction) is performed with good responsiveness and high accuracy. It will be.

In the first embodiment, as shown in FIG. 4, the encoder wheel 86 is installed on the rotary support shaft 84a of the first cam 84, and the encoder sensor 87 is fixedly installed at the position of the base frame 71 corresponding to the encoder wheel 86. Then, the rotation angle (position in the rotation direction) of the first cam 84 (holding frame 72) is adjusted and controlled by the control of the second motor 63 by the detection of the encoder wheel 86 by the encoder sensor 87, and the skew correction of the seat P is performed. It will be done.
Here, the first cam 84 is formed so that the cam curve becomes a constant velocity cam curve. As a result, the amount of change in the rotation angle of the first cam 84 and the amount of change in the rotation angle of the holding frame 72 can be proportional to each other, so that the skew correction control of the seat P can be performed accurately. can.

Here, in the first embodiment, as shown in FIGS. 5 and 8, the reference position (the home position serving as the reference in the rotation direction) of the holding roller pair 31 in the inclination direction (rotation direction) is grasped. Therefore, a filler 84b (arranged so as not to hinder the contact between the first cam 84 and the lever member 81) is formed on the first cam 84, and the presence or absence of the filler 84b is optically detected. The photosensor 15 is fixedly attached to the base frame 71.
Specifically, as shown in FIGS. 5 and 8A, when the filler 84b of the first cam 84 is detected by the photosensor 15, the holding roller pair is controlled by the control unit 90 (see FIG. 16). It is determined that 31 is at the reference position (first reference position) in the tilt direction. On the other hand, as shown in FIGS. 8B and 8C, when the filler 84b of the first cam 84 is not detected by the photosensor 15, the holding roller pair 31 is tilted in the tilt direction by the control unit 90. It is judged that it is not in the reference position (first reference position) of. Therefore, when the pinching roller pair 31 is rotated from the reference position and then returned to the reference position, the second motor 63 is in a state where the filler 84b of the first cam 84 is detected by the photo sensor 15. Will be driven.
The adjustment of the reference position (first reference position) of the sandwiching roller pair 31 will be described in more detail later.

On the other hand, the third driving means is for sliding the holding frame 72 (pinching roller pair 31) in the width direction together with the support shaft 73 moving along the guide portion 71a, and the third motor 62 and the timing belt. It is composed of 97, a second cam 74, a second tension spring 91 as a second urging member, and the like.
The second tension spring 91 as the second urging member connects the holding frame 72 to the base frame 71 so as to urge the holding frame 72 in the positive direction in the width direction (the left direction in FIG. 5). Has been done.
The second cam 74 is rotatably held by the base frame 71 about the rotation support shaft 74a, and the holding frame 72 urged in the forward direction in the width direction by the second tension spring 91 is held in the opposite direction in the width direction. It is pushed (to the right in FIG. 5). A cam follower 75 is installed (shaft support) on the support shaft 73 of the holding frame 72 at a position where it abuts on the second cam 74, and a guide roller 76 (roller) is located at a position where it abuts on the guide portion 71a (base frame 71). Shaped member) is installed (shaft support).
The third motor 62 is fixedly installed on the base frame 71. A timing belt 97 is wound around the drive pulley installed on the motor shaft of the third motor 62 and the driven pulley installed on the rotary support shaft 74a of the second cam 74.

With such a configuration, referring to FIG. 8A, when the third motor 62 is driven, the rotational driving force thereof is transmitted to the second cam 74 via the timing belt 97, and the second cam 74 This causes the holding frame 72 to slide and move so as to resist the spring force of the second tension spring 91.

The spring force of the second tension spring 91 keeps the second cam 74 and the support shaft 73 (cam follower 75) in constant contact with each other, depending on the rotation angle (position in the rotation direction) of the second cam 74. , The moving distance (position in the width direction) of the holding frame 72 (support shaft 73) is determined.
In this way, by making the second cam 74 and the support shaft 73 come into contact with each other via the cam follower 75 as a roller-shaped member, the frictional load generated at the contact position can be extremely reduced. The resist correction will be performed with good responsiveness and high accuracy.

In the first embodiment, as shown in FIG. 4, the encoder wheel 77 is installed on the rotary support shaft 74a of the second cam 74, and the encoder sensor 78 is fixedly installed at the position of the base frame 71 corresponding to the encoder wheel 77. Then, the rotation angle (position in the rotation direction) of the second cam 74 is adjusted and controlled by the control of the third motor 62 by the detection of the encoder wheel 77 by the encoder sensor 78, and the side of the seat P is laterally moved by the sliding movement of the holding frame 72. Resist correction will be performed.
Here, the second cam 74 is formed so that the cam curve becomes a constant velocity cam curve. As a result, the amount of change in the rotation angle of the second cam 74 and the amount of change in the moving distance of the holding frame 72 can be proportional to each other, so that the lateral resist correction control of the sheet P can be performed accurately. Can be done.

FIG. 8C is a diagram showing an example of the operation of the holding frame 72 when the skew correction and the lateral resist correction of the sheet P described above are performed at the same time.
As shown in FIG. 8C, when the second motor 63 is driven and the first cam 84 is rotated, the lever member 81 is pushed by the first cam 84 and rotates about the rotation support shaft 81a. As a result, the holding frame 72 is pushed by the lever member 81 at the position of the protrusion 72a, and the holding frame 72 rotates so as to resist the spring force of the first tension spring 92. At the same time, when the third motor 62 is driven and the second cam 74 is rotated, the holding frame 72 slides and moves by the second cam 74 so as to resist the spring force of the second tension spring 91. At this time, the action roller 83 of the lever member 81 pushes the protrusion 72a (holding frame 72) while moving on the surface of the protrusion 72a.

As described above, in the first embodiment, since the support shaft 73, which is the rotation fulcrum fixed to the holding frame 72 that rotatably holds the holding roller pair 31, is slid and moved, the rotation is rotated with respect to one holding frame 72. Dynamic operation and shift operation (slide movement) are possible. Therefore, neither the second driving means for rotating the holding roller pair 31 nor the third driving means for shifting the holding roller pair 31 needs to be installed on the holding frame 72, and the main body does not need to be installed. It can be installed on a fixed frame (base frame 71). Therefore, the structure that rotates or slides becomes lighter, the responsiveness of these operations can be improved, and the drive source of the second drive means or the third drive means (second motor 63, The power of the third motor 62) can be reduced, and the size and cost of the device can be reduced. Further, in the first embodiment, the first driving means for rotationally driving the sandwiching roller pair 31 is also installed not in the holding frame 72 but in the frame (bracket 69) of the apparatus, so that the above-mentioned effect is further obtained. It will surely be demonstrated.
Further, since the support shaft 73 is shifted and moved by the second cam 74, the contact point between the second cam 74 and the holding frame 72 to be moved becomes one point, and even if the support shaft 73 is rotated, the second cam 74 is used. The support shaft 73 can be smoothly moved along the guide portion 71a while sliding at one point on the surface of the 2 cam 74. Further, since the first cam 84 is in contact with the lever member 81 to be rotated at one point, even if the holding frame 72 shifts, the lever member 81 (holding) slides at one point on the surface of the first cam 84. The frame 72) can be rotated while being smoothly shifted.

Then, the sandwiching roller pair 31 corrects the amount of positional deviation in the tilting direction of the sheet based on the detection results of the two CIS 35 and 36 while conveying the sheet P in a sandwiched state. That is, the sandwiching roller pair 31 functions as a means for performing skew correction (skew correction) of the sheet P by displacing the sheet P transported in the transport path in the tilt direction.
Further, the sandwiching roller pair 31 corrects the amount of positional deviation of the seat P in the width direction based on the detection result of at least one of the two CIS35s and 36s while conveying the seat P in a sandwiched state. That is, the sandwiching roller pair 31 also functions as a means for correcting the lateral resist of the sheet P by displacing the sheet P transported in the transport path in the width direction.

Here, the third transport roller pair 44 is an upstream side transport roller pair installed at a position on the upstream side (upstream side in the transport direction) with respect to the sandwiching roller pair 31. The third transfer roller pair 44 is formed so that the sheet P can be conveyed by rotating in a state where the sheet P is sandwiched, and is formed so as to be separable so that the state in which the sheet P is sandwiched and the state in which the sheet P is not sandwiched can be switched. A pair of transport rollers. Then, when the seat P reaches the position of the pinching roller pair 31 and is pinched and transported by the pinching roller pair 31, the third transport roller pair 44 is switched from the state in which the seat P is pinched to the state in which the seat P is not pinched. become.

Further, in the first embodiment, the sandwiching roller pair 31 is arranged at a position on the upstream side of the transport path with respect to the transfer roller 7 (the downstream transport roller pair forming the transfer nip portion) as a resist roller. It is a transfer roller pair that also functions, and the sheet P (the sheet P after skew correction and lateral resist correction by the sandwiching roller pair 31 itself) is transferred by rotating the sheet P in a state of sandwiching the sheet P. It is conveyed toward the position 7 (a pair of downstream transfer rollers forming the transfer nip portion).
Here, the first motor 61 that rotationally drives the sandwiching roller pair 31 (drive roller 31b) is a rotation speed variable drive motor, and is formed so that the transport speed of the seat P can be changed. Then, when the timing at which the sheet P is conveyed to the position of the sandwiching roller pair 31 is detected by the paper detection sensor (photo sensor) (the sheet P is conveyed to the position of the sandwiching roller pair 31 and the sheet is conveyed by the sandwiching roller pair 31. When the state in which P is pinched is detected), the desired lateral resist correction and skew correction are performed by the pinching roller pair 31, and further, the pinching roller pair 31 performs the desired lateral resist correction and skew correction based on the detection result (detection timing) of the paper detection sensor. The transport speed is changed. That is, the transfer by the sandwiching roller pair 31 so as to match the timing when the sheet P is conveyed to the transfer roller 7 by the sandwiching roller pair 31 and the timing when the image formed on the photoconductor drum 5 reaches the transfer roller 7. The speed is changed (the transfer timing of the sheet P transferred toward the image forming unit is adjusted). As a result, the image can be transferred to a desired position on the sheet P while performing lateral resist correction and skew correction on the sheet P without stopping the transfer of the sheet P by the sandwiching roller pair 31.
It should be noted that the sandwiching roller pair 31 does not cause distortion in the image transferred onto the sheet P due to a linear velocity difference with the photoconductor drum 5 immediately after the tip of the sheet P reaches the transfer nip portion. (The transport speed is changed so that the linear speed ratio with the photoconductor drum 5 becomes 1).

With reference to FIG. 3 and the like, the two CIS 35 and 36 (contact image sensors) as the detection means are on the upstream side of the transport path (transport direction) with respect to the sandwiching roller pair 31, and are the third transport rollers. It is installed on the downstream side of the transport path with respect to the pair 44. In each of the CIS 35 and 36 as the detection means, a plurality of photosensors (consisting of a light emitting element such as an LED and a light receiving element such as a photodiode) are arranged side by side in the width direction, and the sheet P has a plurality of photosensors arranged side by side. It detects the position of the end face Pa (the edge portion on one end side) in the width direction. Then, in the first embodiment, at least one of the two CIS35s and 36s is used to detect the amount of displacement of the lateral resist. That is, the CIS 35 and 36 detect the amount of positional deviation of the sheet P transported in the transport path of the transport device 30 in the width direction. Then, based on the detection results of CIS35 and 36, the lateral resist correction is performed by the sandwiching roller pair 31.
In the first embodiment, as shown in FIG. 3, the CIS36 is installed only on one end side in the width direction to detect the position of the end surface Pa on the one end side in the width direction of the sheet P, but the CIS36 is spread over the entire width direction. It is also possible to install and detect the position of each end face of both ends in the width direction of the sheet P (or the entire width direction of the sheet P).

Then, based on the detection results of CIS35 and 36, the sandwiching roller pair 31 (holding frame 72) is moved in the width direction while the sheet P is sandwiched and conveyed by the sandwiching roller pair 31, and the sheet is conveyed in the conveying path. The positional deviation (horizontal resist) of P in the width direction is corrected.

As a specific example, with reference to FIG. 3, the sheet P has a reference position in the width direction indicated by the alternate long and short dash line (a normal position with no positional deviation in the width direction and a second reference position). When the CIS35 and 36 detect a state in which the position is displaced by the distance α to one end side in the width direction (lower side in FIG. 3), the control unit 90 uses the positional deviation amount α as a correction amount and holds the roller. Before sandwiching and transporting the sheet P by pair 31, the sandwiching roller pair 31 (holding frame 72) is moved from the second reference position to the other end side in the width direction (upper part of FIG. 3) by a distance α. Then, when the sheet P is sandwiched and conveyed by the sandwiching roller pair 31, the sandwiching roller pair 31 is moved to the second reference position.
That is, before the seat P is conveyed to the position of the pinching roller pair 31, the pinching roller pair by the third driving means corresponds to the positional deviation in the width direction of the seat P based on the detection results of CIS35 and 36 (detecting means). The 31 is moved in the width direction from the second reference position, and then the sandwiching roller pair 31 in the state where the seat P is sandwiched is moved to the second reference position by the third driving means so that the positional deviation in the width direction is corrected. Will be done.

Further, the two CIS 35 and 36 also function as a second detecting means for detecting the skew amount (positional deviation amount) in the tilt direction of the sheet P transported in the transport path.
Specifically, as described above, the two CIS 35s and 36s are arranged side by side at positions on the upstream side in the transport direction with respect to the sandwiching roller pair 31 at positions separated from each other in the transport direction. Then, the skew amount β (skew amount) of the sheet P is obtained from the deviation of the position of the end face Pa of the sheet P detected by the two CIS 35 and 36 and the separation distance of the two CIS 35 and 36, respectively. Then, in the first embodiment, skew correction is performed while sandwiching and transporting the sheet P by the sandwiching roller pair 31 based on the detection results of the two CIS 35 and 36.

As a specific example, with reference to FIG. 3, the sheet P is angled in the positive direction (positive direction in the rotation direction) with respect to the reference position in the width direction indicated by the alternate long and short dash line (a normal position without skewing). When the state of skewing by β is detected by the two CIS 35 and 36, the control unit 90 (see FIG. 16) uses the skew amount β as a correction amount, and the sheet P is sandwiched and conveyed by the sandwiching roller pair 31. The sandwiching roller pair 31 (holding frame 72) is rotated by an angle β from the reference position (first reference position) in the opposite direction (the direction opposite to the rotation direction and the clockwise direction in FIG. 3). Let me. Then, when the seat P is sandwiched and conveyed by the sandwiching roller pair 31, the sandwiching roller pair 31 is rotated to the first reference position.
That is, before the sheet P is conveyed to the position of the sandwiching roller pair 31, the second is such that the sheet P faces the sheet P in response to the skew amount of the sheet P based on the detection results of the CIS 35 and 36 (second detecting means). The sandwiching roller pair 31 is rotated from the reference position (first reference position) by the driving means, and then the sandwiching roller pair 31 in the state where the seat P is sandwiched is referenced by the second driving means so that the skew amount is corrected. It will rotate to the position (first reference position).

As described above, in the first embodiment, the sandwiching roller pair 31 rotates in the tilting direction based on the detection results of CIS35 and 36 in a state where the sheet P is sandwiched and conveyed without stopping the transfer of the sheet P. By doing so, the skew amount in the tilt direction of the sheet P is corrected, and the position deviation amount in the width direction of the sheet P is corrected by moving in the width direction based on the detection results of CIS35 and 36.
As a result, the productivity of the apparatus can be significantly improved as compared with the case where the transfer of the sheet P is stopped and the skew correction and the lateral resist correction are performed separately. Further, when performing skew correction or lateral resist correction, there is no difference in linear speed between the roller portions installed in the width direction in the sandwiching roller pair 31, so that the thin paper or the sheet P having a low surface friction coefficient is used. Even when the paper is passed through, the sheet P does not bend or slip.

Hereinafter, an example of the operation of the transfer device 30 configured as described above will be described in detail with reference to FIGS. 9 and 10.
9 (A1) to (C1) and 10 (A1) to (B1) are top views showing the operation of the transport device 30 in that order, and FIGS. 9 (A2) to 9 (C2). 10 (A2) to (B2) are side views of the transport device 30 corresponding to the operations of FIGS. 9 (A1) to (C1) and FIGS. 10 (A1) to 10 (B1), respectively.
First, as shown in FIGS. 9 (A1) and 9 (A2), the sheet P fed from the paper feed unit 12 is sandwiched and conveyed toward the position of the sandwiching roller pair 31 by the third transport roller pair 44. (Transportation in the direction of the white arrow.). At this time, the position of the holding roller pair 31 in the rotation direction is at the first reference position (a regular position corresponding to the sheet P without skew), and the position in the width direction is the second reference position (horizontal resist). It is in the regular position corresponding to the sheet P without the positional deviation of.).
Then, when the sheet P reaches the positions of the CIS 35 and 36, the position deviation amount α of the lateral resist of the sheet P is detected by the CIS 35 and 36. Specifically, in the first embodiment, the value obtained by averaging the positional deviation amounts detected by the two CIS 35 and 36, respectively, is obtained as the positional deviation amount α. Further, the skew amount β of the sheet P is detected by the two CIS 35 and 36. Since the amount of positional deviation in the width direction directly detected by CIS35 and 36 is in a state where the sheet P is skewed, the skewing amount is based on the detection result of the detected skew amount. The control unit 90 (calculation unit) obtains the position deviation amount α of the lateral resist in the case where the resistance is not present.

After that, as shown in FIGS. 9 (B1) and 9 (B2), the sandwiching roller pair 31, together with the holding frame 72, is centered on the support shaft 73 in the same inclination direction according to the skew amount β detected by the CIS 35 and 36. It rotates from the first reference position by the angle β, and shifts from the second reference position by the distance α in the same width direction according to the position deviation amount α detected by CIS35 and 36.
Then, as shown in FIGS. 9 (C1) and 9 (C2), the rotational drive of the sandwiching roller pair 31 (rotational drive in the direction of the arrow in the figure) is performed immediately before the tip of the sheet P reaches the sandwiching roller pair 31. When the sheet P is started and sandwiched and conveyed by the sandwiching roller pair 31, the third transport roller pair 44 opens the conveying path and moves apart in the direction in which the sheet P is not sandwiched (in the direction of the solid arrow). The timing at which the tip of the seat P reaches the pinching roller pair 31 is the timing at which the tip of the seat P is detected by the CIS 35, 36, the transport speed of the seat P, and the pinching roller pair 31 from the positions of the CIS 35, 36. It can also be obtained by the calculation unit (control unit 90) based on the distance to the position and the like.

Then, as shown in FIGS. 10 (A1) and 10 (A2), the sandwiching roller pair 31 holds the support shaft 73 so as to offset the skew amount β detected by the CIS 35 and 36 while sandwiching and transporting the sheet P. It rotates to the center so as to return to the first reference position, and moves in the width direction so as to cancel the position deviation amount α detected by CIS35 and 36 so as to return to the second reference position.

Then, as shown in FIGS. 10B1 and 10B, the sheet P subjected to skew correction and lateral resist correction is conveyed toward the transfer roller 7 (transfer nip portion). At this time, the rotation speed of the sandwiching roller pair 31 (the transport speed of the sheet P until reaching the transfer roller 7) is changed so as to match the timing with the image on the photoconductor drum 5. Then, the image is transferred to a desired position on the sheet P.
After that, the third transport roller pair 44, which was in the separated state, is returned to the contact state (the state of FIG. 9A2) to prepare for the transport operation of the sheet P to be transported next.

Hereinafter, the characteristic configuration and operation of the transfer device 30 according to the first embodiment will be described in detail with reference to FIGS. 11 to 17 and the like.
As described above, the transport device 30 in the first embodiment is configured to be able to rotate the sandwiching roller pair 31 in the tilt direction (direction parallel to the sheet transport surface) with respect to the transport direction. Drive means 63, 81 to 84, 98 are provided. Then, in the normal transfer process (image forming process), the skew amount of the sheet P is dealt with based on the detection results of CIS35 and 36 (second detection means) before the sheet P is transferred to the position of the sandwiching roller pair 31. Then, the sandwiching roller pair 31 is rotated from the reference position (first reference position) by the second driving means 63, 81 to 84, 98 so as to face the seat P, and then the seat P is sandwiched. The roller pair 31 is rotated to a reference position (first reference position) by the second drive means 63, 81 to 84, 98 so that the skew amount is corrected.

However, as shown in FIG. 11, the first reference position of the pinching roller pair 31 is the target position (the position indicated by the broken line) due to the assembly error of various components such as the pinching roller pair 31 and the component error. ) Sometimes deviated.
Specifically, the assembly error / component error of the rotating mechanism such as the holding roller pair 31, the holding frame 72, and the base frame 71, and the second driving means 63, 81 to 84, 98 for driving the holding roller pair 31 in the tilting direction. Due to the assembly error and component error of the photo sensor 15 that detects the first reference position of the pinching roller pair 31 and the filler 84b (first cam 84), the pinching roller pair 31 The first reference position of was sometimes deviated from the target position. In particular, the sandwiching roller pair 31 is the device main body 1 (or the transport device 30), such as the third transport roller pair 44 on the upstream side thereof and the transfer roller 7 (and the photoconductor drum 5) on the downstream side thereof. Since it is not held by the housing via bearings but is rotatably held by the transport device 30 in the tilting direction via many parts, the various assembly errors and parts errors described above occur. When piled up, the deviation of the first reference position becomes non-negligible.
Then, as shown in FIG. 11, when the first reference position of the sandwiching roller pair 31 as the first roller pair deviates from the target position, the skew correction of the seat P by the sandwiching roller pair 31 is performed with high accuracy. It will disappear. Further, if the first reference position of the sandwiching roller pair 31 as the first roller pair deviates from the target position, the transfer roller 7 (and the photoconductor drum 5) as the second roller pair (downstream side transport roller pair) are displaced. ) Is not sufficiently parallel to the sheet P, and the sheet P is sandwiched and conveyed by the sandwiching roller pair 31 and the transfer roller 7 (and the photoconductor drum 5), and the sheet P is transferred between both rollers. A force that expands and contracts in the width direction acts, causing wrinkles on the sheet P.

In response to such a problem, in the first embodiment, control for adjusting the reference position (first reference position) in the tilt direction of the sandwiching roller pair 31 at a predetermined timing (hereinafter, “reference position adjustment mode” as appropriate). The accuracy of skew correction of the seat P by the pinching roller pair 31 can be improved, and the problem of wrinkles on the seat P pinched and conveyed by the pinching roller pair 31 can be reduced. Can be done.

Here, in the first embodiment, the "reference position adjustment mode" performed by the control unit 90 (see FIG. 16) is the sandwiching roller pair 31 (first roller pair) by the second drive means 63, 81 to 84, 98. ) Is rotated in a direction parallel to the sheet transport surface to multiple stages of rotation positions, and the sheet P is held in each stage with the sandwiching roller pair 31 and the downstream transfer roller pair 5, 7 (second roller pair). The time change of the position of the end face Pa in the width direction of the sheet P is detected by CIS35, 36 (detection means), and the rate of time change after the sheet P reaches the nip portion of the sandwiching roller pair 31. The rotation position at which the rate of change over time after the sheet P reaches the nip portion of the downstream transfer roller pair 5 and 7 and the rotation position substantially coincides with each other is set as the reference position. More specifically, the rotation position at which the difference between the two time change ratios described above is substantially the same is obtained by calculation, and the rotation position is set as the reference position.
That is, in the "reference position adjustment mode", the sandwiching roller pair 31 (first roller pair) is rotated by the second driving means 63, 81 to 84, 98 into a plurality of rotation positions in a direction parallel to the sheet transport surface. By moving the sheet P, the sheet P is conveyed by the sandwiching roller pair 31 and the downstream transfer roller pairs 5 and 7 (second roller pair), and the position of the widthwise end surface Pa of the sheet P is changed by two time changes. Detected by CIS35 and 36, respectively, and based on the detection results of each of the two CIS35 and 36, the rate of time change after the sheet P reaches the nip portion of the sandwiching roller pair 31 and the sheet P. The rate of change over time after reaching the nip portion of the downstream transfer roller pair 5 and 7 and the rotation position that substantially coincides with each other are calculated and set as the reference position (they). The reference position is set from the ratio of).
The above-mentioned "rate of change with time" is the rate of change of the vertical axis component (position) with respect to the horizontal axis component (time) in the graph of FIG. 12, which will be described later, and it is assumed that the graph is a straight line. Then, it corresponds to "tilt".

From another point of view, in the "reference position adjustment mode", the tilting direction of the sandwiching roller pair 31 is changed by the second driving means 63, 81 to 84, 98 in a plurality of stages, and the seat P is sandwiched in each stage. CIS35 and 36 (detection means) detect changes in the position of the end face Pa in the width direction of the sheet P while sandwiching and transporting the sheet P between the pair 31 and the transfer roller 7 (and the photoconductor drum 5), and the detection results thereof are obtained. Based on this, the reference position (first reference position) in the tilt direction of the sandwiching roller pair 31 is determined so that the above-mentioned change (time change) becomes a linear change. That is, in the "reference position adjustment mode", the tilting direction of the sandwiching roller pair 31 is changed in a plurality of stages by the second driving means 63, 81 to 84, 98, and the seat P is sandwiched by the sandwiching roller pair 31 in each stage. The change in the position of the end face Pa in the width direction of the sheet P is detected by the two CIS 35 and 36 while being conveyed, and the above-mentioned change becomes a linear change based on the detection results of the two CIS 35 and 36, respectively. In addition, the reference position (first reference position) in the tilt direction of the sandwiching roller pair 31 is determined.

Specifically, in the "reference position adjustment mode" in the first embodiment, the tilting direction of the sandwiching roller pair 31 is changed in a plurality of stages by the second driving means 63, 81 to 84, 98, and the seat P is set for each stage. While being sandwiched and conveyed by the sandwiching roller pair 31, the sheet P is sandwiched and conveyed by the transfer roller 7 and the photoconductor drum 5 (downstream transfer roller pair) to change the position of the end face Pa in the width direction of the sheet P. It is detected by CIS35 and 36 over the front and back, and the reference position (first reference position) in the tilt direction of the sandwiching roller pair 31 is determined so that the above-mentioned change becomes a linear change based on the detection result. There is.

The "reference position adjustment mode" is a control in which the sheet P is sandwiched and conveyed by the sandwiching roller pair 31 at each stage in order to determine the first reference position, and is a normal transfer process (image forming process). Is done at the timing when is not done. The control unit 90 controls to sandwich and convey the sheet P by the sandwiching roller pair (first roller pair) at each stage in order to determine the first reference position, at the timing when the normal transfer process is not performed. It will be done. That is, when the "reference position adjustment mode" is executed, the test sheet P is conveyed from the paper feed units 12 to 14 via the transfer path in the same manner as during normal image formation, but the sheet P is conveyed. Does not form an image on the surface of. It is preferable that the sheet P conveyed in the reference position adjustment mode has a high linearity of the end face Pa in the width direction.

A further supplementary explanation will be given.
In the "reference position adjustment mode", the tilt angle θ of the pinching roller pair 31 is swung by multiple levels from θ1 to θ5 (see FIG. 17), the sheet P is repeatedly conveyed, and the transition of the detection data of CIS35 and 36 becomes a straight line. The closest tilt angle θ (the tilt angle θ at which the ratios of time changes substantially match) is obtained by calculation by the control unit 90, and the tilt angle θ is determined as the first reference position. When the sheet P is sandwiched and conveyed in a state where the sandwiching roller pair 31 is tilted in the tilting direction, the sheet P is skewed with a skew amount corresponding to the tilt angle θ. Therefore, the time transition (rate of time change) of the detection data of the two CIS35 and 36 changes with a constant increasing / decreasing tendency with the skew amount of the sheet P and its transportation. However, if the parallelism between the pinching roller pair 31 and the transport roller pair on the upstream / downstream side thereof (particularly, the downstream side transport roller pair) is not sufficient, the increase / decrease tendency changes, resulting in poor skew correction. Wrinkles will occur. Therefore, the rotation position (inclination angle θ) of the sandwiching roller pair 31 in which the change in the increasing / decreasing tendency is minimized is derived.
In the reference position adjustment mode, the holding roller pair 31 and the third transport roller pair 44 are not separated from each other.

Specifically, in the first embodiment, the inclination angle θ of the pinching roller pair 31 is set in 5 steps (5 levels) from θ1 to θ5 (see FIG. 17), and the pinching roller pair 31 times are set in each of these settings. A test transfer is performed with the moving position fixed, and the detection results of the seat end face positions of the two CIS 35 and 36 are measured. FIG. 12 shows an example of the measurement results of the five settings (θ1 to θ5), where the horizontal axis shows the time (milliseconds) and the vertical axis shows the position (micrometer) of the end face Pa. be. That is, FIG. 12 shows the time change of the seat end face position. Further, in FIG. 12, “CIS1” indicates the detection result by the first CIS35, and “CIS2” indicates the detection result by the second CIS36. Further, in FIG. 12, when the time is 100 ms, the sheet P reaches the nip portion of the sandwiching roller pair 31, and when the time is 350 ms, the sheet P reaches the transfer nip portion on the downstream side. Is reached.
As shown in FIG. 12, the amount of inclination of the graph, which tends to increase or decrease, differs depending on the inclination angle θ of the sandwiching roller pair 31, but between the nip before and after the sheet P reaches the nip portion and the transfer nip portion of the sandwiching roller pair 31. The straight line changes due to the parallelism of. In particular, in FIG. 12, the inclination amount (rate of time change) of the graph changes in each of the three sections A, B, and C separated by the broken line. That is, the slope (ratio of time change) when the three sections A to C are linearly approximated changes. This change in inclination is a change in the position in the width direction of the sheet P caused by the transfer direction of the sandwiching roller pair 31 being different from that of the transfer roller pair on the upstream / downstream side. For example, under the condition that the rotation HP adjustment value is −200, the slope of the graph differs between the section A and the section B, and the graph looks like a curve.

FIG. 13 is a plot of the amount of change in the inclination angle θ and the inclination of the graph in the sections B to C from the result of FIG. 12, and the horizontal axis is the inclination angle (rotation HP adjustment value) of the sandwiching roller pair 31. ), And the vertical axis shows the linearity of the change in the seat end face position. In the example of FIG. 13, the rotation HP adjustment with the smallest amount of change in the slope of the graph (the linearity of the change in the seat end face position and the consistency of the ratio of the time change between the section B and the section C). It can be seen that the value is at the position of about 50. That is, when the first reference position of the pinching roller pair 31 is set so that the tilt angle θ of the pinching roller pair 31 corresponds to the rotation HP adjustment value 50, the sheet P detected by the CIS 35, 36. The change in the position of the end face Pa in the width direction becomes linear. Then, by adjusting and setting the first reference position and performing the normal transfer process in this way, the parallelism between the sandwiching roller pair 31 and the transfer roller 7 (and the photoconductor drum 5) is improved, and high accuracy is achieved. Along with the smooth skew correction, the occurrence of wrinkles will be reduced.

Here, in the first embodiment, the "reference position adjustment mode" performed by the control unit 90 is set on the sheet transport surface of the sandwiching roller pair 31 (first roller pair) by the second driving means 63, 81 to 84, 98. The sheet P is rotated in a direction parallel to the inside to a plurality of stages of rotation positions, and the sheet P is rotated into a third transfer roller pair 44 (upstream side transfer roller pair), a sandwiching roller pair 31 and a downstream side transfer roller pair 5 for each stage. , 7 while being conveyed by at least the sandwiching roller pair 31 and the downstream transfer roller pairs 5 and 7, the sheet P changes the position of the widthwise end surface Pa of the sheet P with respect to the position of the sandwich roller pair 31. The rate of change over time after the sheet P reaches the nip portion of the sandwiching roller pair 31 after being detected by CIS35, 36 (detection means) from before reaching It is also possible to set the reference position from the rate of time change after the sheet P reaches the nip portion (transfer nip portion) of the downstream transfer roller pair 5 and 7.

From another point of view, the "reference position adjustment mode" is changed by the second drive means 63, 81 to 84, 98 in multiple stages of the tilting direction of the sandwiching roller pair 31, and the seat P is sandwiched in each stage. While being sandwiched and conveyed by the pair 31 or / and the third transfer roller pair 44 (upstream transfer roller pair), the change in the position of the widthwise end face Pa of the sheet P is changed to the position of the sandwich roller pair 31 by the sheet P. It is detected by CIS35, 36 (detection means) from before it reaches until it is sandwiched and conveyed by the transfer roller 7 (downstream transfer roller pair), and the above-mentioned change becomes a linear change based on the detection result. In addition, it is also possible to determine the first reference position in the tilt direction of the holding roller pair 31.
That is, in FIG. 13, the amount of change in the inclination of the graph between the section A and the section B in FIG. 12 is also plotted, and the inclination angle θ of the sandwiching roller pair 31 at which the amount of change becomes zero is set as the first reference position. You can also decide.
When a transparent color or black sheet P is transported in a normal transport process (image forming process), it becomes difficult to optically detect the end face Pa of the sheet P by CIS35 and 36, so that skew correction control and lateral resist are performed. Correction control may not be performed. In such a case, since it is not necessary to perform the separation operation of the third transport roller pair 44, the third transport roller pair 44 is controlled to be in contact with each other at all times. In such a case, if the parallelism between the third transport roller pair 44 and the pinching roller pair 31 is not sufficient, the sheet P sandwiched and transported by the third transport roller pair 44 and the pinching roller pair 31 will have wrinkles. Since it will occur, the reference position adjustment mode as described above becomes useful.

Further, in the first embodiment, two CIS35s and 36s are used as the detection means in the "reference position adjustment mode", but only one CIS of the two CIS35s and 36s is used as the detection means in the "reference position adjustment mode". Can also be used. However, when two CIS35s and 36s arranged at positions separated from each other in the transport direction are used as in the first embodiment, even when the end surface Pa of the sheet P is uneven and the linearity is low. Since the end face Pa of the sheet P is determined by combining the two detection results, the first reference position of the sandwiching roller pair 31 can be determined with relatively high accuracy.
Further, in the first embodiment, the inclination angle θ of the pinching roller pair 31 is set in 5 steps in the “reference position adjustment mode”, but the tilt angle θ of the pinching roller pair 31 is set in any other number of 2 steps or more. It can also be set.

In the first embodiment, the "reference position adjustment mode" is not executed only once before the transfer device 30 (image forming device 1) is started to be used, and is not executed only once, but at intervals to some extent. Therefore, it is executed every time the cumulative number of sheets to be passed reaches a predetermined value.
This is because the assembly error and component error of various components described above (particularly, component error) change due to wear and deterioration over time, and the first reference position once adjusted changes. This is because it will be done.
By appropriately executing the "reference position adjustment mode" even over time, it is possible to perform highly accurate skew correction even over time and reduce the problem of wrinkles on the sheet P.

In the present embodiment, in the "reference position adjustment mode" performed by the control unit 90, the rate of time change detected by the CIS 35 and 36 after the seat P reaches the nip portion of the sandwiching roller pair 31 and the rate thereof. The rotation position that substantially coincides with the rate of time change detected by CIS35 and 36 after the sheet P reaches the nip portion of the downstream transfer roller pair 5 and 7 is calculated and the rotation position is determined. It was set as one reference position.
On the other hand, in the "reference position adjustment mode" performed by the control unit 90, the sandwiching roller pair 31 (first roller pair) is directed by the second driving means 63, 81 to 84, 98 in a direction parallel to the sheet transport surface. The sheet P is rotated to multiple rotation positions, and the sheet P is conveyed by the sandwiching roller pair 31 and the downstream transfer roller pairs 5 and 7 (second roller pair) in each step, and the end face in the width direction of the sheet P is conveyed. The time change of the position of Pa is detected by CIS35, 36 (detection means), and the ratio of the time change after the sheet P reaches the nip portion of the sandwiching roller pair 31 and the sheet P being the downstream transfer roller pair. It is also possible to set the rotation position where the difference between the rate of change with time after reaching the nip portions of 5 and 7 and the minimum difference is set as the reference position. More specifically, it is also possible to obtain one rotation position from a plurality of stages of rotation positions that minimizes the difference between the two time change ratios described above, and set the rotation position as a reference position.
That is, to explain with the examples of FIGS. 12 and 13, the amount of change in the inclination of the graph (the linearity of the change in the position of the end face of the sheet, which is the interval, among the ones in which the inclination angle θ of the sandwiching roller pair 31 is shaken in five stages. The inclination angle θ (the rotation HP adjustment value is 100) at which the time change ratio between B and the section C is the smallest is set as the first reference position.
Even when controlled in this way, the parallelism between the sandwiching roller pair 31 and the transfer roller 7 (and the photoconductor drum 5) is increased, highly accurate skew correction is performed, and wrinkles are formed. Occurrence will also be reduced.

Hereinafter, control in the reference position adjustment mode will be described as a summary with reference to FIG.
As shown in FIG. 14, first, it is determined whether it is the timing to execute the reference position adjustment mode (step S1), and when it is determined that it is the timing to execute, the reference position adjustment mode is started.
First, the inclination angle of the sandwiching roller pair 31 is set to θ1 by the second driving means 63, 81 to 84, 98 (step S2). Then, while the pinching roller pair 31 is maintained at the inclination angle θ1, the test sheet P is conveyed, and the detection result R1 of the end surface Pa of the sheet P is acquired by CIS35 and 36 (step S3). Hereinafter, according to the predetermined number of steps n (five steps in the first embodiment), the inclination angle θm (m = 1 to 31) of the sandwiching roller pair 31 is increased by one step from 1 to the step number m. The setting of n), the transfer of the sheet P under the setting conditions, and the acquisition of the detection results Rm (m = 1 to n) of CIS35 and 36 are repeated (steps S2 to S5). That is, the inclination angles θ of the sandwiching roller pair 1 are sequentially changed to θ1 to θ5 (see FIG. 17), and the detection results R1 to R5 of CIS35 and 36 corresponding to the respective inclination angles θ1 to θ5 are acquired.
Then, all the detection results R1 to Rn are aggregated (step S6), and the reference position (first reference position) of the sandwiching roller pair 31 is determined so that the change of the detection result becomes linear (step S7). ), End this flow.
Then, until the reference position adjustment mode is performed next and the reference position of the sandwiching roller pair 31 is changed, the skew correction control is performed based on the value (tilt angle) of the reference position.

Finally, as a supplement to the description in the first embodiment, the skew correction and the lateral resist correction described above with reference to FIGS. 9, 10 and the like will be described with reference to FIGS. 15 and 16.
FIG. 15 is a flowchart showing a control flow until "skew correction and lateral resist correction" are performed, and FIG. 16 is a block diagram showing a control unit 90 related to those corrections.
As shown in FIG. 15, first, two CIS (in the first correction, the first CIS35 and the second CIS36) detect the sheet P (step S21), and the position of the sheet P in the width direction. The deviation amount α and the skew amount β are detected (step S22). Then, based on these detection results, the correction amount α'and the skew correction amount β'in the width direction are calculated (step S23), and the correction amount is determined.
Then, based on this correction amount, the encoder count number is calculated by each encoder (the second and third motor encoders shown in FIG. 16) (step S24). Then, the second motor 63 and the third motor 62 are driven by the respective motor drivers (the second and third motor drivers shown in FIG. 16) according to the calculated encoder count number, and the sandwiching roller pair is used. As the 31 rotates and slides, the pick-up operation is performed (step S25). Then, after the sandwiching roller pair 31 sandwiches the seat P, the sandwiching roller pair 31 is rotated and slid so as to return to the reference position by the drive of the second and third motors 62 and 63, and skew correction and skew correction are performed. Lateral resist correction is performed (step S26). When the picking operation of step S25 or the correction of step S26 is performed, the position information of the pinching roller pair 31 is momentarily fed back by the second and third motor encoders, and the pinching roller pair 31 is determined. It is controlled to move by the amount of movement.

In FIG. 16, the control unit 90 controls various operations in the image forming apparatus. The position recognition unit in the control unit 90 counts the position deviation amount and the skew amount in the width direction of the sheet P from the information received from the first and second CIS 35 and 36, respectively. Further, the second motor control unit determines the drive amount (rotation angle and rotation direction) of the second motor 63 based on the skew amount obtained from the position recognition unit. Further, the third motor control unit determines the drive amount (rotation angle and rotation direction) of the third motor 62 based on the position deviation amount in the width direction obtained from the position recognition unit. The second and third motor drivers receive signals from the second and third motor control units, respectively, and drive the second and third motors, respectively. The second and third motor encoders detect the respective rotation amounts of the second and third motors.

As described above, in the transport device 30 according to the first embodiment, a plurality of sandwiching roller pairs 31 (first roller pairs) are provided by the second drive means 63, 81 to 84, 98 in a direction parallel to the sheet transport surface. The widthwise end face Pa of the sheet P is transported by the sandwiching roller pair 31 and the downstream side transport roller pairs 5 and 7 (second roller pair) by rotating the sheet P to the rotation position of each step. The time change of the position is detected by CIS35, 36 (detection means), and the ratio of the time change after the sheet P reaches the nip portion of the sandwiching roller pair 31 and the sheet P is the downstream transfer roller pair 5, A control unit 90 is provided that sets a rotation position that substantially coincides with the rate of change over time after reaching the nip portion of No. 7 as a reference position.
As a result, skew correction of the sheet P transported in a predetermined transport direction can be performed with high accuracy.

In the first embodiment, the present invention is applied to the transfer device 30 in which the sandwiching roller pair 31 that functions as the horizontal resist / skew correction roller also functions as the resist roller, but the present invention can be applied. The transfer device is not limited to this, and the present invention is naturally applied to all transfer devices having other configurations as long as they are transfer devices that perform skew correction. be able to. For example, the present invention can naturally be applied to a transfer device in which a resist roller is installed on the downstream side of a holding roller pair 31 that functions as a lateral resist / skew correction roller.
Further, in the first embodiment, the present invention is applied to the transport device 30 that performs skew correction and horizontal resist correction of the transfer paper as the sheet P on which the image is formed, but the skew correction of the original as the sheet P is performed. As a matter of course, the present invention can be applied to a transport device that performs horizontal resist correction.
Further, in the first embodiment, the present invention is applied to the transport device 30 installed in the monochrome image forming apparatus 1, but the present invention is naturally applied to the transport device installed in the color image forming apparatus. The invention can be applied.
And even in those cases, the same effect as that of the first embodiment can be obtained.

Further, in the first embodiment, the sheet P is conveyed by the sandwiching roller pair 31 as the first roller pair and the second roller pairs 5 and 7 (downstream transfer roller pair) arranged on the downstream side thereof. However, the time change of the end face in the width direction of the sheet P is detected by CIS35, 36 (detection means), and the rate of the time change after the sheet P reaches the nip portion of the sandwiching roller pair 31 and the sheet P. The rate of change over time after reaching the nip portion of the second roller pair 5 and 7 and the reference position (first reference position) were set. On the other hand, while the sheet is conveyed by the first roller pair and the second roller pair arranged on the upstream side thereof, the time change of the end face in the width direction of the sheet is detected by the detecting means, and the sheet is detected. The rate of time change after reaching the nip part of the second roller pair and the rate of time change after the sheet reaches the nip part of the first roller pair, and the reference position (first reference position). It can also be configured to set.
And even in such a case, the same effect as that of the first embodiment can be obtained.

<Embodiment 2>
FIG. 18 will explain in detail the second embodiment of the present invention.
FIG. 18 is an overall configuration diagram showing the image forming apparatus 100 according to the second embodiment. The image forming apparatus 100 according to the second embodiment is different from that of the first embodiment, which is an electrophotographic type, in that the image forming apparatus 100 is of an inkjet type.
In FIG. 18, 100 is an inkjet printer as an image forming apparatus, 102 is a transport drum for transporting the sheet P, 103 is a downstream transport roller pair as a second roller pair for transporting the sheet P together with the sandwiching roller pair 31, and 104 is. A transport roller that transports the sheet P toward the transport drum 102, and 105 indicates a clipper that grips the sheet P on the transport drum 102.
Further, 106 is a separating member for separating the sheet P from the transport drum 102, 107 is a transport belt for transporting the sheet P separated from the transport drum 102, and 108 is a paper discharge tray on which the printed sheet P is discharged / loaded. , Is shown.
Further, 110Y, 110M, 110C, and 110K indicate a recording head (printing module) in which an image forming unit for printing / printing by an inkjet method is unitized.
The inkjet type image forming apparatus 100 according to the second embodiment is also provided with the characteristic transport device 30 as in the first embodiment.

Here, the image forming apparatus 100 in the second embodiment is for forming a color image, and as shown in FIG. 18, a recording head 110K for black and three colors for color (yellow, Recording heads 110Y, 110M, 110C, and the like are installed. These four recording heads 110Y, 110M, 110C, and 110K are arranged side by side so as to face the transport drum 102 and along the rotation direction of the transport drum 102.
The four recording heads 110Y, 110M, 110C, and 110K have almost the same structure except that the colors (types) of the inks used for printing are different. The main parts of the recording heads 110Y, 110M, 110C, and 110K are composed of a piezoelectric actuator, a thermal actuator, or the like, and a nozzle for ejecting ink as droplets, an ink tank filled with ink, or a control board ( A control unit) and the like are provided.

The operation of the image forming apparatus 100 will be briefly described with reference to FIG.
First, when a print command is input to the control unit of the image forming apparatus 100 from a personal computer or the like together with image information, the sheet P is fed from the paper feed cassette 12 by the paper feed roller 40. The sheet P supplied from the paper feed cassette 12 is conveyed toward the transfer drum 102 by the transfer device 30. At this time, in the transport device 30, the width direction and rotation of the sheet P by the sandwiching roller pair 31 (first roller pair) are based on the detection results of the two CIS 35 and 36, as in the case of the first embodiment. Positional deviation correction in the moving direction is performed.
On the other hand, in the recording heads 110Y, 110M, 110C, 110K of each color, it is converted into the writing information of each color based on the input image information.
Then, the sheet P conveyed to the transfer drum 102 is positioned on the transfer drum 102 in a state of being gripped by the clipper 105, and is conveyed along the counterclockwise direction of the transfer drum 102.
Then, ink as droplets is sequentially sprayed from the recording heads 110Y, 110M, 110C, 110K of each color on the sheet P conveyed in the direction of the arrow in FIG. 18 by the rotation of the conveying drum 102 based on the writing information. A desired color image is formed on the sheet P.
After that, the sheet P on which the desired image is formed is separated from the transport drum 102 by the separating member 106. Then, the sheet P separated from the transport drum 102 is transported by the transport belt 107 and discharged onto the paper output tray 108.

As described above, the transport device 30 (image forming device 100) in the second embodiment has the sandwiching roller pair 31 (first roller pair) by the second driving means, similarly to the one in the first embodiment. While rotating the sheet P to multiple stages of rotation positions in a direction parallel to the sheet transport surface and transporting the sheet P by the sandwiching roller pair 31 and the downstream transfer roller pair 103 (second roller pair) at each stage. The time change of the position of the end face Pa in the width direction of the sheet P is detected by CIS35, 36 (detection means), and the ratio of the time change after the sheet P reaches the nip portion of the sandwiching roller pair 31 and the sheet P. A control unit 90 is provided that sets a rotation position that substantially coincides with the rate of change over time after reaching the nip portion of the downstream transfer roller pair 103 as a reference position.
As a result, skew correction of the sheet P transported in a predetermined transport direction can be performed with high accuracy.
As a matter of course, all of the modifications described in the first embodiment can be applied to the second embodiment as well.

<Embodiment 3>
FIG. 19 will explain in detail the third embodiment of the present invention.
FIG. 19 is an overall configuration diagram showing the image forming apparatus 1 according to the third embodiment. The image forming apparatus 1 in the third embodiment is provided with a post-processing apparatus 150 that performs post-processing such as perforation processing, binding processing, and folding processing on the sheet P after image formation. It is different from the one in the form of.
In FIG. 19, 150 is a post-processing device detachably installed on the image forming apparatus main body, 151 is a perforating device for perforating a sheet P after image formation, and 152 is a sheet P after image forming. 153 indicates a binding device that performs a binding process on the sheet P, and 153 indicates a folding device that performs a folding process on the sheet P after image formation. Further, 155 indicates a first output tray, 156 indicates a second output tray, and 157 indicates a third output tray. Further, 158 indicates a downstream transfer roller pair as a second roller pair that conveys the sheet P together with the sandwiching roller pair 31.
Further, the post-processing device 150 in the third embodiment is also provided with a characteristic transport device 30 as in the case of each of the above-described embodiments.

The first transport path K1 is a path for discharging the sheet P that has been punched by the punching device 151 or the sheet P that has not been post-treated to the first paper ejection tray 155.
Further, the second transport path K2 is a path for transporting the sheet P toward the binding device 152 and discharging the sheet bundle after the binding process to the second paper ejection tray 156.
Further, the third transport path K3 is a path for transporting the sheet P toward the folding device 153 and discharging the sheet P after the middle folding process to the third paper ejection tray 157.

The operation of the post-processing device 150 will be briefly described with reference to FIG.
First, the sheet P discharged from the image forming apparatus main body 1 is conveyed into the post-processing apparatus 150. Then, in the transport device 30, the positional deviation correction in the width direction and the rotation direction of the sheet P by the sandwiching roller pair 31 is performed based on the detection results of the two CIS 35 and 36, as in the case of each of the above-described embodiments. It is carried out. After that, the position-corrected sheet P is transported to one of the three transport paths K1 to K3 according to the post-processing specified by the user, is subjected to the designated post-processing, and is one of the output trays. It will be discharged from 155 to 157.

As described above, the transport device 30 (post-processing device 150) in the third embodiment has the sandwiching roller pair 31 (first roller pair) by the second driving means, as in the case of each of the above-described embodiments. While rotating the sheet P to multiple stages of rotation positions in a direction parallel to the sheet transport surface and transporting the sheet P by the sandwiching roller pair 31 and the downstream transfer roller pair 158 (second roller pair) at each stage. The time change of the position of the end face Pa in the width direction of the sheet P is detected by CIS35, 36 (detection means), and the rate of the time change after the sheet P reaches the nip portion of the sandwiching roller pair 31 and the sheet P. A control unit 90 is provided that sets a rotation position that substantially coincides with the rate of change over time after reaching the nip portion of the downstream transfer roller pair 158 as a reference position.
As a result, skew correction of the sheet P transported in a predetermined transport direction can be performed with high accuracy.
In particular, in the third embodiment, the post-processing device 150 can perform highly accurate post-processing with less positional deviation of the sheet P.
As a matter of course, all of the modifications described in the first embodiment can be applied to the third embodiment as well.

In each of the above embodiments, the present invention has been applied to the transport device 30 installed in the electrophotographic image forming apparatus 1 and the transport device 30 installed in the inkjet image forming apparatus 100. The application of the present invention is not limited to this, and it may be a transport device installed in another type of image forming apparatus (for example, an offset printing machine) or a transport device that performs skew correction. For example, the present invention can naturally be applied to all of these transport devices.
Even in such a case, the same effect as that of the present embodiment can be obtained.

Further, in each of the above-described embodiments, the first driving means is configured to indirectly push the holding frame 72 (projection portion 72a) by the first cam 84 via the lever member 81, but the first cam is used. The first driving means can also be configured to directly push the holding frame.
Further, in each of the above-described embodiments, the second drive means is configured so as to directly push the holding frame 72 (support shaft 73) by the second cam 74, but the holding frame is indirectly pushed by the second cam. The second driving means can also be configured to be pushed.
Further, in each of the above-described embodiments, the cam mechanism is used as the second and third drive means, respectively, but the second and third drive means are not limited thereto, and for example, the second and third drive means are used. A solenoid mechanism, a pinion rack mechanism, or the like can also be used.
And even in those cases, the same effect as that of each of the above-described embodiments can be obtained.

It should be noted that the present invention is not limited to each of the above-described embodiments, and within the scope of the technical idea of the present invention, each of the above-described embodiments may be appropriately modified in addition to those suggested in the above-described embodiments. Is clear. Further, the number, position, shape and the like of the constituent members are not limited to each of the above-described embodiments, and the number, position, shape and the like suitable for carrying out the present invention can be used.

In the specification of the present application, etc., the term "sheet" includes all sheet-like members such as coated paper, label paper, transparencies, films, metal sheets, and prepregs, in addition to ordinary paper. Define.

1 Image forming apparatus (image forming apparatus main body),
5 Photoreceptor drum (second roller pair, downstream transfer roller pair),
7 Transfer roller (second roller pair, downstream transfer roller pair),
15 photo sensor,
30 Conveyor,
31 Holding roller pair (first roller pair, resist roller),
31a driven roller,
31b drive roller,
35 1st CIS (detection means, 2nd detection means),
36 Second CIS (detection means, second detection means),
44 Third transport roller pair (upstream transport roller pair),
51 Matching part,
61 First motor (first driving means),
62 Third motor (third drive means),
63 Second motor (second drive means),
74 Second cam (third driving means),
84 1st cam (2nd driving means),
84b filler,
90 Control unit,
P sheet (recording medium).

Japanese Unexamined Patent Publication No. 2016-175776

Claims (9)

A transport device that transports sheets in a transport path.
A detection means for detecting the position of the end face in the width direction of the sheet transported in the transport path, and
A first roller pair, which is rotationally driven by the first drive means, conveys the seat while being sandwiched between the nip portions, and is configured to be rotatable in a direction parallel to the sheet transport surface by the second drive means.
A second roller pair, which is arranged on the downstream side in the transport direction or the upstream side in the transport direction with respect to the first roller pair, and transports the sheet together with the first roller pair in a state of being sandwiched between the nip portions.
The first roller pair is rotated by the second driving means into a plurality of stages of rotation positions in a direction parallel to the sheet transport surface, and the sheet is rotated into the first roller pair and the second roller at each stage. The detection means detects a time change in the position of the end face in the width direction of the sheet while being conveyed by the pair, and the rate of the time change after the sheet reaches the nip portion of the first roller pair and the said. A control unit that sets a rotation position that substantially coincides with the rate of change over time after the sheet reaches the nip portion of the second roller pair as a reference position.
A transport device characterized by being equipped with. A transport device that transports sheets in a transport path.
A detection means for detecting the position of the end face in the width direction of the sheet transported in the transport path, and
A first roller pair, which is rotationally driven by the first drive means, conveys the seat while being sandwiched between the nip portions, and is configured to be rotatable in a direction parallel to the sheet transport surface by the second drive means.
A second roller pair, which is arranged on the downstream side in the transport direction or the upstream side in the transport direction with respect to the first roller pair, and transports the sheet together with the first roller pair in a state of being sandwiched between the nip portions.
The first roller pair is rotated by the second driving means into a plurality of stages of rotation positions in a direction parallel to the sheet transport surface, and the sheet is rotated into the first roller pair and the second roller at each stage. The detection means detects a time change in the position of the end face in the width direction of the sheet while being conveyed by the pair, and the rate of the time change after the sheet reaches the nip portion of the first roller pair and the said. A control unit that sets a rotation position that minimizes the difference between the rate of change over time after the seat reaches the nip portion of the second roller pair as a reference position, and a control unit.
A transport device characterized by being equipped with. The second roller pair is a downstream transport roller pair arranged at a position on the downstream side in the transport direction with respect to the first roller pair.
It is provided with an upstream side transport roller pair which is arranged at a position on the upstream side in the transport direction with respect to the first roller pair and transports a sheet toward the position of the first roller pair.
The control unit rotates the first roller pair to a plurality of stages of rotation positions in a direction parallel to the sheet transport surface by the second drive means, and the sheet is transferred to the upstream side transport roller at each stage. While transporting by at least the first roller pair and the downstream transport roller pair among the pair, the first roller pair, and the downstream side transport roller pair, the time change of the position of the end face in the width direction of the sheet is changed. The sheet is detected by the detection means from before the sheet reaches the position of the first roller pair until it is conveyed by the downstream transfer roller pair, and after the sheet reaches the nip portion of the first roller pair, the sheet is said. The first or second aspect of claim 1, wherein the reference position is set from the time change rate and the time change rate after the sheet reaches the nip portion of the second roller pair. Conveyor device. A second detecting means for detecting a skew amount in a direction parallel to the sheet transport surface of the sheet transported in the transport path is provided.
The second control unit faces the sheet in response to the skew amount of the sheet based on the detection result of the second detection means before the sheet is conveyed to the position of the first roller pair. The first roller pair is rotated from the reference position by the driving means, and then the reference position is corrected by the second driving means so that the skew amount of the first roller pair in a state where the sheet is sandwiched is corrected. The transport device according to any one of claims 1 to 3, wherein the transport device rotates in the same direction. The transport device according to claim 4, wherein the second detection means is the detection means. A third driving means configured to move the first roller pair in the width direction based on the detection result of the detecting means is provided.
Before the sheet is conveyed to the position of the first roller pair, the control unit responds to the positional deviation of the sheet in the width direction based on the detection result of the detection means by the third driving means. The second reference position is moved by the third driving means so that the roller pair is moved in the width direction from the second reference position and then the position deviation of the first roller pair in a state where the sheet is sandwiched is corrected. The transport device according to claim 4 or 5, wherein the transport device moves to. The detection means are two CIS arranged side by side at positions separated from each other in the transport direction at a position upstream of the transport direction with respect to the first roller pair.
The control unit rotates the first roller pair in a direction parallel to the sheet transport surface to a plurality of stages of rotation positions by the second drive means, and the sheet is rotated in each stage by the first roller pair. The time change of the position of the end face in the width direction of the sheet is detected by the two CIS while being conveyed by the second roller pair, and each of the two CIS is based on the detection result of each of the two CIS. The reference position is determined from the rate of change in time after the sheet reaches the nip portion of the first roller pair and the rate of change in time after the sheet reaches the nip portion of the second roller pair. The transport device according to any one of claims 1 to 6, wherein the transfer device is set. The control unit is characterized in that, in order to determine the reference position, the control of sandwiching and transporting the sheet by the first roller pair at each step is performed at a timing when the normal transport process is not performed. The transport device according to any one of claims 1 to 7. An image forming apparatus comprising the transport device according to any one of claims 1 to 8.

Images