JP2020121827A - Shift device, sheet conveying device, and image forming apparatus - Google Patents

Abstract

To provide a shift device, a sheet conveying device, and an image forming apparatus, capable of accurately shifting a position in a width direction of a sheet to a target position.SOLUTION: While a guide member such as an inner guide member is moved away from a guide position by separation means such as a guide drive unit prior to a shift action that shifts a sheet of paper or other material in a width direction, the sheet is transported by making a sheet conveying speed of a first shift conveying member pair, such as a resist roller pair, faster than a sheet conveying speed of a second shift conveying member pair, such as a relay roller pair.SELECTED DRAWING: Figure 12

Description

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

Conventionally, at least one of the pair of transport members is arranged to be movable in the width direction, which is a direction orthogonal to the sheet transport direction, and a first shift transport member pair, and is arranged upstream of the first shift transport member pair in the sheet transport direction. A pair of conveying members, at least one of which is movable in the width direction, and a guide member which is disposed between the second shift conveying member pair and the first shift conveying member pair and which guides the sheet. A shift device equipped with and is known.

In Patent Document 1, as the shift device, after the leading end of the sheet is abutted against the first shift conveying member pair, the sheet is bent by a predetermined amount between the first shift conveying member pair and the second shift conveying member pair. , Sheet conveyance by the first shift conveyance member pair is started. Then, with the sheet sandwiched between the first shift conveying member pair and the second shift conveying member pair, the conveying members of the first shift conveying member pair and the second shift conveying member pair are moved in the width direction. Then, it is described that the position in the width direction of the seat is shifted to a target position.

However, in the shift device described in Patent Document 1, there is a possibility that the position in the width direction of the sheet cannot be accurately shifted to the target position.

In order to solve the problems described above, the present invention provides a first shift conveyance member pair in which at least one of a pair of conveyance members is movable in a width direction that is a direction orthogonal to the sheet conveyance direction, and the first shift conveyance. A second shift conveyance member pair, which is disposed upstream of the member pair in the sheet conveyance direction and at least one of a pair of conveyance members is movable in the width direction, the second shift conveyance member pair, and the first pair. A shift device provided between a shift conveyance member pair and a guide member for guiding a sheet, comprising a separating means for separating the guide member from a guide position for guiding the sheet, and the sheet in the width direction. Prior to the shift operation of shifting the sheet to the guide position by the separating means from the guide position, the sheet conveying speed of the first shift conveying member pair is set to be smaller than the sheet conveying speed of the second shift conveying member pair. It is also characterized in that the sheet is conveyed at high speed.

According to the present invention, the widthwise position of the seat can be accurately shifted to the target position.

1 is a schematic configuration diagram of a printer according to the present embodiment. The schematic diagram which shows an example of the conventional shift device. FIG. 8 is a diagram showing an example of a state of a sheet between a relay conveyance roller pair and a registration roller pair during a shift operation for shifting the position of the sheet in the width direction in a conventional shift device. The schematic diagram which shows the shift device of this embodiment. FIG. 3 is a schematic diagram of a roller driving device that drives a registration roller pair and a relay roller pair. The schematic diagram which shows the modification of a roller drive device. The schematic diagram which shows a guide drive device. The schematic diagram which shows the modification of a guide drive device. The perspective view of a shift mechanism. The principal part expansion perspective view of a shift drive part. The block diagram which shows an example of the principal part structure of the control system in the shift device which concerns on this embodiment. The control flow figure of the shift operation in a shift device.

An electrophotographic printer (hereinafter, simply referred to as a printer) that forms an image by an electrophotographic method will be described below as an image forming apparatus including the sheet conveying device according to the present invention. In the present embodiment, a color laser printer will be described as an example of the image forming apparatus. However, the image forming apparatus is not limited to a color type and may be a monochrome type. Image forming apparatus may be used. Further, the image forming apparatus provided with the sheet conveying apparatus according to the present invention is not limited to the electrophotographic system, and may be an image forming apparatus of another system such as an inkjet system.

FIG. 1 is a schematic configuration diagram of a printer 100 according to the present embodiment.
In the printer 100, an intermediate transfer belt 16 is provided substantially in the center of the printer body 1. Above the intermediate transfer belt 16, four image forming units 2 (Y, M, C, and Y) that perform image formation with toners of respective colors of yellow (Y), cyan (C), magenta (M), and black (K). K) are arranged side by side. Since the configurations and operations of the four image forming units 2 (Y, M, C, K) are substantially the same, the reference numerals indicating the colors are omitted here and the image forming units will be described.

The image forming unit 2 includes a photoconductor 12 that is a latent image carrier that faces the stretched surface above the intermediate transfer belt 16. Around the photoconductor 12, a charging device 11 that is a charging unit and a line forming device. A laser scanning unit 10 as a means, a developing device 13 as a developing means, and the like are provided. Further, the primary transfer roller 14 facing the photoconductor 12 with the intermediate transfer belt 16 interposed therebetween is provided to form a primary transfer nip.
A secondary transfer roller 15 is provided below the intermediate transfer belt 16, and a secondary transfer counter roller 16a that faces the secondary transfer roller 15 with the intermediate transfer belt 16 interposed therebetween is provided to form a secondary transfer nip. ..
At the bottom of the printer body 1, a sheet feeding device 20 which is a sheet conveying device in which first to third sheet feeding trays 5 of three stages can be pulled out from the apparatus body is provided. A paper P made of transfer paper or resin film is accommodated.

When the printing operation is started by the printer 100, the photoconductor 12 is rotationally driven counterclockwise in FIG. 1, and the intermediate transfer belt 16 is rotationally driven clockwise in FIG. At this time, the charging device 11 uniformly charges the surface of the photoconductor 12 to a predetermined polarity. Next, the uniformly-charged surface of the photoconductor 12 is irradiated with laser light based on image information from the laser scanning unit 10 of each color, whereby an electrostatic latent image is formed on the photoconductor 12. Then, the electrostatic latent image formed on the surface of the photoconductor 12 is visualized as a toner image by the developing device 13, and the toner image is transferred to the intermediate transfer belt 16 by the primary transfer roller 14 at the primary transfer nip. .. The transfer residual toner adhering to the surface of the photoconductor 12 after the toner image transfer is removed by the photoconductor cleaning device.

At the time of forming a color image, the above-mentioned image forming operation is performed by all the image forming units 2, whereby the yellow toner image, the cyan toner image, the magenta toner image, and the black toner image formed on the individual photoconductors 12 are intermediate. The images are sequentially transferred and transferred onto the transfer belt 16.

On the other hand, the paper P is fed from the paper feeding device 20. When the user selects the paper feed tray 5 to be used from the three paper feed trays 5 by using the operation panel 3 or an input terminal such as a personal computer, the paper P stored in the selected paper feed tray 5 is stored. It is fed.
A broken line indicated by reference numeral “19” in FIG. 1 indicates a conveyance path along which the paper P passes through the printer 100.

The fed paper P is sent toward the registration roller pair 18 and abutted on the registration roller pair 18 whose front end is stopped.
After the paper P is aligned by this, the registration roller pair 18 sends the paper P toward the secondary transfer nip at the timing matching the toner image on the intermediate transfer belt 16. The transfer residual toner adhering to the surface of the intermediate transfer belt 16 after the toner image is transferred at the secondary transfer nip is removed by the intermediate transfer belt cleaning device.

The sheet P on which the unfixed toner image is transferred at the secondary transfer nip is sent to the fixing device 17, and after the unfixed toner image is fixed on the sheet P, in the case of single-sided printing, it is discharged to the discharge tray 4. It
In the case of double-sided printing, the sheet P on which the image is formed on the first side is transported to the double-sided route by switching the transporting route by the branching claw 40. The paper P sent out to the reversing roller pair 41 by the branching claw 40 is conveyed to the double-sided roller pair 42 by the forward and reverse rotation of the reversing roller pair 41. At this time, the front and back sides of the sheet P in the transport direction are reversed from those at the time of image formation on the first side. Then, after the sheet P is conveyed to the relay roller pair 43 and the registration roller pair 18, an image is formed on the second surface by the same process as described above, and then the sheet P is ejected to the sheet ejection tray 4.

The user can optionally connect a paper feed bank capable of feeding a large amount of paper P to the printer body 1 or a finisher capable of stapling and folding instead of the paper discharge tray 4.

In addition, in the present embodiment, the paper is shifted in the width direction upstream of the secondary transfer nip in the paper conveyance direction, the positional deviation in the width direction of the fed paper is corrected, and the image position on the paper is shifted. A device 50 is provided. The shift device 50 of this embodiment includes a registration roller pair 18 that is a first shift conveyance member pair and a relay roller pair 43 that is a second shift conveyance member pair, and at least one roller of these roller pairs (this embodiment In the configuration, the registration drive roller 18a and the relay drive roller 43a) are configured to be movable in the width direction. Further, a paper detection sensor 46 for detecting the widthwise end portion of the paper is provided on the downstream side of the registration roller pair 18 in the paper conveyance direction.

The fed paper is conveyed to the registration roller pair 18 via the relay roller pair 43. After the leading edge of the sheet hits the stationary registration roller pair 18, the sheet P is subjected to a predetermined bending between the relay roller pair 43 and the registration roller pair 18, and skew correction is performed, and then the registration roller pair is formed. The sheet 18 is conveyed by rotating 18. With respect to the paper P conveyed by the pair of registration rollers 18, the paper detection sensor 46 detects the end position of the paper in the width direction. The shift amount (correction amount) in the width direction of the sheet is determined based on the end position of the sheet in the width direction detected by the sheet detection sensor 46 and the target position previously stored in the storage unit. Based on the amount, a shift operation for shifting the position in the width direction of the paper to a target position is executed. Accordingly, the position in the width direction of the paper can be positioned at the target position and can be conveyed to the secondary transfer nip, and the image can be transferred at the target position of the paper.

FIG. 2 is a schematic diagram showing an example of a conventional shift device.
Conventionally, the relay roller pair 43 is configured to be immovable in the width direction, and at the time when the leading edge of the sheet reaches the sheet detection sensor 46 (see FIG. 2A), it is upstream of the registration roller pair 18 in the transport direction. Then, one conveying roller of the conveying roller pair (relay roller pair 43 or vertical conveying roller pair 44) that holds the sheet is separated from the other conveying roller pair (see FIG. 2B). Then, only the registration roller pair 18 is moved in the paper width direction to shift the paper width direction position.

FIG. 3 is a diagram showing an example of the state of the sheet P between the relay roller pair 43 and the registration roller pair 18 during the shift operation for shifting the position in the width direction of the sheet in the conventional shift device.
As described above, the leading edge of the sheet conveyed to the registration roller pair 18 strikes the registration roller pair 18 which is stopped, and a predetermined bending is formed between the relay roller pair 43 and the registration roller pair 18 to skew the sheet. We are making corrections. At this time, how to bend the paper depends on the state of the paper (rigidity or curl of the paper). Therefore, as shown by the dotted line S in FIG. 3A, in a case where only the outer guide member 52 of the pair of guide members 51 and 52 arranged between the relay roller pair 43 and the registration roller pair 18 comes into contact, As shown by dotted lines S1 and S2 in FIG. 3B, depending on the state of the sheet (stiffness or curl of the sheet), the guide member may be contacted with both the outer guide member 52 and the inner guide member 51. The way of contact is different.

When the paper is shifted in the width direction in the state where the paper is in contact with the inner guide member 51 and the outer guide member 52 as described above, the paper rubs against the outer guide member 52 and the inner guide member 51, and the rubbing is performed. It becomes a resistance when the paper P is shifted in the width direction. Since the contact state of the sheet with the guide members 51 and 52 differs depending on the state of the sheet as described above, the resistance when shifting the sheet P in the width direction differs depending on the state of the sheet. As a result, depending on the state of the paper P, it may not be possible to shift the paper P to the target position, and it may not be possible to transfer the image to the target position of the paper P.

Further, due to the sliding resistance, the sheet is twisted between the relay roller pair 43 and the registration roller pair 18, and the sheet is pinched by the registration roller pair in a twisted state, so that the sheet may be damaged such as wrinkles. There is also.

As shown in FIG. 3, when the shift operation is performed, by separating the relay roller pair 43, the bending of the sheet between the relay roller pair 43 and the registration roller pair 18 is eliminated, but during the shift operation. The behavior of the paper is not stable, the paper may come into contact with the guide member, and the paper P may not be shifted to the target position.

When the conveyance path from the relay roller pair 43 to the registration roller pair 18 has a curved shape, the sheet is bent and reaches the registration roller pair 18. Therefore, during the shift operation, the paper is likely to contact the guide member, and there is a high possibility that the paper P cannot be shifted to the target position.

Therefore, it is conceivable to make the conveyance path from the relay roller pair 43 to the registration roller pair 18 linear. By making the conveyance path from the relay roller pair 43 to the registration roller pair 18 linear, the behavior of the paper when the rollers of the relay roller pair are separated from each other is stabilized, as compared with a curved conveyance path. Therefore, the contact with the guide member can be suppressed. However, it is necessary to secure a space in the apparatus that allows straight line conveyance, which may increase the size of the printer. It is also possible to eliminate the manual feed tray, reduce the number of sheets loaded in the paper feed tray, or reduce the number of paper feed stages to secure a space for straight line conveyance without increasing the size of the printer. There is a problem that it drops the specifications of.

It is also conceivable to attach a slidable sheet such as PTFE to the surfaces of the guide members 51 and 52 facing the paper to reduce the sliding resistance between the guide members and the paper. However, there is a possibility that cost may increase due to an increase in the number of parts. Further, when the slidable sheet is attached to the guide member, it is necessary to carefully attach the slidable sheet to the guide member in order to prevent air bubbles from entering, which may lead to an increase in the cost of the device. There is also. Furthermore, there is a possibility that the sliding portion of the sliding sheet with respect to the paper may disappear due to wear with use over time, and slidability may not be secured over time. Further, even with such a configuration, since the paper slides on the guide member during the shift operation, the sliding resistance cannot be zero, and the highly accurate shift operation cannot be completely realized.

Further, when shifting the paper in the width direction, it is conceivable to separate both the outer guide member 52 and the inner guide member 51 from the guide position shown in FIG. 3 so that they are not in contact with the paper. However, it is necessary to secure both a space in which the outer guide member 52 can be separated and a space in which the inner guide member 51 can be separated, which may increase the size of the printer. Further, it is necessary to provide a mechanism for separating the outer guide member 52 and a mechanism for separating the inner guide member 51, which may lead to an increase in the size of the printer and an increase in the cost of the printer due to an increase in the number of parts. Furthermore, since the way the paper is bent and the behavior of the paper during conveyance differ depending on the state of the paper, it is necessary to greatly separate the guide members for safety in order to prevent the sheet from contacting the guide members. There is also a risk that it will lead to a larger size.

Therefore, in the present embodiment, the sheet conveyance speed of the registration roller pair 18 is made higher than the sheet conveyance speed of the relay roller pair 43 to eliminate the bending of the sheet between the relay roller pair 43 and the registration roller pair 18. The inner guide member is separated from the guide position so that the sheet does not contact the guide member, and then the shift operation is performed.

FIG. 4 is a schematic diagram showing the shift device 50 of the present embodiment.
In the present embodiment, both the registration roller pair 18 and the relay roller pair 43 are provided with rollers movable in the width direction. The inner guide member 51 is divided into an upstream guide portion 51a and a downstream guide portion 51b. The upstream guide portion 51a has an upstream end rotatably supported, and is configured to be rotatable between a guide position shown in FIG. 4(a) and a separated position shown in FIG. 4(b). ing. The downstream guide portion 51b has a downstream end rotatably supported, and is configured to be rotatable between a guide position shown in FIG. 4(a) and a separated position shown in FIG. 4(b). ing. With such a configuration, the inner guide member 51 can retract the sheet from the guide position.

As shown in FIG. 4B, before the shift operation for correcting the position of the paper P in the width direction, the paper carrying speed V1 of the registration roller pair 18 is made faster than the paper carrying speed V2 of the relay roller pair 43. (V1>V2). In this way, by feeding the paper with a speed difference, the bent paper between the relay roller pair 43 and the registration roller pair 18 is straightened, and the paper is pulled. Therefore, during the shift operation, the paper between the relay roller pair 43 and the registration roller pair 18 is in a straight posture substantially along the line segment connecting the nip of the relay roller pair and the nip of the registration roller pair. Decided. As a result, even if the orientation of the sheet when the tip of the sheet is abutted against the pair of registration rollers and skew is corrected varies depending on the state of the sheet, the shift operation can always be performed in the orientation shown in FIG. 4B. .. Thereby, the sheet can be reliably separated from the outer guide member 52 during the shift operation.

Further, when the bending of the sheet between the relay roller pair 43 and the registration roller pair 18 is eliminated, the sheet approaches the inner guide member 51 side and comes into contact with the inner guide member 51. Therefore, before starting the shift operation, the upstream guide portion 51a and the downstream guide portion 51b of the inner guide member 51 are rotated from the guide position shown by the one-dot chain line in FIG. 4B to the separated position shown by the solid line in the figure. Let As a result, it is possible to prevent the sheet from coming into contact with the inner guide member 51. As a result, it is possible to prevent the sheet from sliding on the outer guide member 52 and the inner guide member 51 during the shift operation.

Accordingly, during the shift operation, the sheet can be smoothly shifted in the width direction without receiving sliding resistance, and the position of the sheet in the width direction can be accurately positioned at the target position. In addition, due to the sliding resistance with the guide member, the paper between the relay roller pair and the registration roller pair is not twisted, and it is possible to suppress the occurrence of wrinkles or the like on the paper.

Further, in the present embodiment, the posture of the sheet between the relay roller pair 43 and the registration roller pair 18 during the shift operation is determined to be the posture shown in FIG. 4B, and there is a possibility that the sheet comes into contact with this posture. If only the inner guide member 51 is movable from the guide position to the separated position, it is possible to prevent the sheet from coming into contact with the guide member during the shift operation. As a result, the number of parts can be reduced and the cost of the device can be reduced compared to the configuration in which the outer guide member 52 and the inner guide member 51 are moved from the guide position to the separated position. Further, since the posture of the seat during the shift operation is determined as shown in FIG. 4B, it is easy to determine how much the inner guide member 51 should be separated from the guide position so that the inner guide member 51 and the seat do not come into contact with each other. Can be grasped. As a result, it is possible to prevent contact between the inner guide member 51 and the sheet with a minimum required amount of movement, the moving space of the inner guide member 51 can be reduced, and space can be saved.

Further, in the present embodiment, the paper P can be accurately shifted in the width direction even if the conveyance path between the relay roller pair 43 and the registration roller pair 18 has a curved shape. As a result, the paper P can be accurately shifted in the width direction without lowering the specifications of the printer or increasing the size of the printer.

Further, in this embodiment, the inner guide member 51 is divided into an upstream guide portion 51a and a downstream guide portion 51b. Thereby, as compared with the case where one end of the inner guide member 51 is rotated to move the inner guide member 51 from the guide position to the separated position, the upstream guide portion 51a and the downstream guide portion 51b are separated from the guide position. The amount of movement of the other end to can be greatly reduced. As a result, as compared with the case where the inner guide member 51 is not divided, the space required to move the inner guide member 51 from the guide position to the separated position can be narrowed, and the enlargement of the device can be suppressed.

FIG. 5 is a schematic diagram of a roller driving device 90 that drives the registration roller pair 18 and the relay roller pair 43.
The roller driving device 90 includes a registration driving unit 80 that drives the registration roller pair 18, and a relay driving unit 70 that drives the relay roller pair 43. The registration drive unit 80 includes a registration motor 81, a timing belt 82 spanning a drive pulley 82a provided on the motor shaft of the registration motor 81 and a driven pulley 82b provided on the shaft of the registration drive roller 18a. ..

The relay drive unit 70 has the same configuration as the registration drive unit 80. That is, the timing belt 72 includes a relay motor 71, a drive pulley 72a provided on the motor shaft of the relay motor 71, and a driven pulley 72b provided on the shaft of the relay drive roller 43a.

The relay motor 71 and the registration motor 81 are connected to the control unit 200 so that the control unit 200 makes the sheet conveyance speed V1 of the registration roller pair 18 faster than the sheet conveyance speed V2 of the relay roller pair 43. Controlled. Before the shift operation of shifting the position of the width direction of the paper is started, the paper conveyance speed of the registration roller pair 18 and the paper of the relay roller to the paper are set so that the paper between the registration roller pair 18 and the relay roller pair 43 may be pulled over. A speed difference (V1-V2) from the transport speed is set.

Further, the control unit 200 is provided with a torque detection sensor 201 that detects the torque of the registration driving roller 18a. The control unit 200 feedback-controls the relay motor 71 so that the detected value of the torque detection sensor 201 is maintained at substantially 0 (the torque of the registration driving roller is substantially 0), and the sheet conveyance speed V1 of the registration roller pair 18 is controlled. And the speed difference between the sheet conveying speed V2 of the relay roller pair 43 is adjusted.

In the present embodiment, as described above, the sheet conveyance speed V1 of the registration roller pair 18 is made faster than the sheet conveyance speed V2 of the relay roller pair 43 (V1>V2), and a speed difference is established between the registration roller pair 43 and the relay roller pair 43. The shift operation is started after the sheet bending between the registration roller pair 18 is eliminated and the sheet is pulled. However, even if the sheet between the relay roller pair 43 and the registration roller pair 18 is pulled, if the speed difference is still kept, abnormal images and wrinkles may occur due to excessive pulling. May occur.

Therefore, the control unit 200 causes the torque detection sensor 201 to detect an increase in the torque of the registration driving roller 18a caused by the pulling of the sheet between the relay roller pair 43 and the registration roller pair 18. Then, the control unit 200 feedback-controls the relay motor 71 so that the torque becomes almost zero. Specifically, when the torque increases, control is performed to increase the sheet transport speed V2 of the relay roller pair 43.

As a result, after the sheet bending between the relay roller pair 43 and the registration roller pair 18 is eliminated and the sheet is pulled, the difference in sheet conveyance speed between the relay roller pair 43 and the registration roller pair 18 is eliminated, and the sheet is pulled too much. It is possible to suppress the occurrence of image abnormalities and wrinkles on the paper.

Further, it is preferable that only the sheet conveyance speed V2 of the relay roller pair 43 is changed based on the detection value of the torque detection sensor 201, and the sheet conveyance speed V1 of the registration roller pair 18 is kept constant. By keeping the sheet conveying speed V1 of the registration roller pair 18 constant, the sheet conveying speed to the secondary transfer nip does not change, and the influence on the secondary transfer can be suppressed.

Further, in the present embodiment, the torque of the registration drive roller 18a is detected by the torque detection sensor 201, but the torque of the relay drive roller 43a is detected by the torque detection sensor 201 to determine the sheet conveyance speed V2 of the relay roller pair 43. You may change it. In this case, when the torque detection sensor 201 detects a decrease in the torque, feedback control is performed to increase the sheet conveyance speed V2 of the relay roller pair 43, and thereby the sheet between the relay roller pair 43 and the registration roller pair 18 is performed. Can prevent excessive pulling.

Further, in the above description, the timing belt is used to transmit the driving force to the rollers (the relay driving roller 43a and the registration driving roller 18a), but the gear may be used to transmit the driving force to the rollers.

FIG. 6 is a schematic diagram showing a modified example of the roller driving device 90.
In the roller driving device of this modification, one motor drives the registration roller pair 18 and the relay roller pair 43.
As shown in FIG. 6, the drive transmission to the relay drive roller 43a is performed by the timing belt 92 stretched around the drive pulley provided with the motor shaft and the driven pulley provided on the shaft of the relay drive roller as in the case of FIG. The driving force of the common motor 91 is transmitted via the. On the other hand, the drive force is transmitted to the registration drive roller 18a via the transmission 94.

The first timing belt 93 wound around a drive pulley provided on the motor shaft of the common motor 91 is wound around a pulley provided coaxially with the transmission 94. The second timing belt 95 wound around a pulley provided on the shaft of the registration driving roller 18 a is wound around the transmission 94. The transmission 94 is composed of a plurality of pulleys having different diameters and a changing unit that changes the pulley around which the second timing belt 95 is wound. A continuously variable transmission mechanism may be used as the transmission.

A clutch is provided in the drive transmission unit that transmits the driving force to the registration drive roller 18a. By providing the clutch, when the skew of the paper is corrected by abutting the leading end of the paper against the registration roller pair 18 and bending the paper by a predetermined amount, the clutch is disengaged to stop the drive of the registration drive roller 18a and the relay drive roller Only 43a can be rotationally driven to convey the paper.

The control unit 200 is connected to the common motor 91 and the transmission 94. When the torque detection sensor 201 detects an increase in torque, the drive speed of the common motor 91 is increased to increase the sheet conveyance speed V2 of the relay roller pair 43. Speed up. Further, the transmission 94 is controlled to change the speed reduction ratio so that the sheet conveying speed V1 of the registration roller pair 18 is kept constant. As a result, when the sheet between the relay roller pair 43 and the registration roller pair 18 is pulled, the difference between the sheet conveyance speed of the relay roller pair 43 and the sheet conveyance speed of the registration roller pair 18 becomes almost zero, and the sheet It is possible to suppress excessive pulling.

Further, the transmission 94 may be provided on the side that transmits the driving force to the relay drive roller 43a. In this case, the drive speed of the common motor 91 is controlled to be constant at the sheet conveying speed V1 of the registration roller pair 18, and the transmission 94 is controlled based on the detection result of the torque detection sensor 201 to reduce the reduction ratio. Is changed to change the sheet conveyance speed V2 of the relay roller pair.

Next, the guide drive device 130 that moves the inner guide member 51 between the guide position and the separated position will be described.

FIG. 7 is a schematic view showing the guide driving device 130.
The guide drive device 130 as a separating unit includes a first guide drive section 110 that moves the upstream guide section 51a of the inner guide member 51 and a second guide drive section 120 that moves the downstream guide section 51b.
The first guide drive unit 110 is stretched over a first guide motor 111, a drive pulley provided on the first guide motor, and a driven pulley provided on the rotary shaft X2 of the upstream guide unit 51a. It is composed of a guide timing belt 112.

The second guide drive unit 120 has the same configuration as the first guide drive unit 110, and includes a second guide motor 121, a drive pulley provided on the second guide motor, and a rotation axis X1 of the downstream guide unit 51b. It is composed of a driven pulley provided and a second guide timing belt 122 stretched around the driven pulley.

By rotating the first guide motor 111 counterclockwise in the drawing for a predetermined time as shown by an arrow D1, the upstream guide portion 51a rotates from the guide position shown by the dotted line in the drawing to the separated position. (Arrow E1 in the figure). Further, by rotating the second guide motor 121 clockwise in the drawing for a predetermined time as shown by an arrow D2 in the drawing, the downstream guide portion 51b is rotated from the guide position shown by the dotted line in the drawing to the separated position. (Arrow E2 in the figure). When the shift operation is completed, the guide motors 111 and 121 are driven to rotate in the opposite direction to the direction shown by the arrow in FIG. 7 for a predetermined time, thereby returning the guide portions 51a and 51b from the separated position to the guide position.

In the above description, the timing belt is used to transmit the driving force to the guide portion (the upstream guide portion 51a and the downstream guide portion 51b), but the gear may be used to transmit the driving force to the guide portion. Further, a solenoid may be used to move the guide portion between the guide position and the separated position.

FIG. 8 is a schematic diagram showing a modified example of the guide drive device 130.
The guide drive device 130 shown in FIG. 8 is configured such that one motor moves the upstream guide portion 51a and the downstream guide portion 51b between a guide position and a separated position.
In this modification, the structure for transmitting the driving force to the downstream guide portion 51b has the same structure as in FIG. That is, the second guide timing belt 122 is stretched around the drive pulley provided on the common guide motor 131 and the driven pulley provided on the rotary shaft X1 of the downstream guide portion 51b.

On the other hand, in the configuration for transmitting the driving force to the upstream guide portion 51a, a pulley around which the first guide timing belt 112 is wound is provided coaxially with an idler gear that meshes with a gear provided on the motor shaft of the common guide motor 131. There is. Thereby, the upstream guide portion 51a and the downstream guide portion 51b can be moved between the guide position and the separated position by one motor.

Next, the shift mechanism 60 that moves the registration roller pair 18 and the relay roller pair 43 in the width direction will be described.

FIG. 9 is a perspective view of the shift mechanism 60, and FIG. 10 is an enlarged perspective view of a main part of the shift drive unit 61.
The shift mechanism 60 rotatably supports the registration drive roller 18a and the relay drive roller 43a, and includes a roller support portion 66 configured to be movable in a predetermined range in the width direction with respect to the printer body, and a roller support portion 66. , And a shift driving unit 61 for moving the width direction within a predetermined range.

The shaft 118a of the registration driving roller 18a and the shaft 143a of the relay driving roller 43a are rotatably supported by the front side plate 66a and the back side plate 66b of the roller support portion 66 via bearings. The front side plate 66a is provided with a relay drive unit 70 (see FIG. 5) for driving the relay drive roller 43a, and the back side plate 66b is provided with a registration drive unit 80 (FIG. 5) for driving the registration drive roller 18a. (See) is provided.

The shift drive unit 61 has a shift motor 65, and the motor shaft 65a of the shift motor 65 is provided so as to be orthogonal to the width direction (also the axial direction of the roller). A shift drive pulley 65b is provided on the motor shaft 65a of the shift motor 65. The shift timing belt 63 is stretched around the shift drive pulley 65b and a shift driven pulley 62 which is provided at a predetermined distance in the width direction from the motor shaft 65a and whose rotation axis center is parallel to the motor shaft 65a. .. A connecting member 64 fastened to a fixing plate 67 of a roller supporting portion 66 is fixed to the shift timing belt 63.

By driving the shift motor 65, the shift timing belt 63 rotates, and the connecting member 64 moves in the width direction together with the shift timing belt 63. As a result, the shift motor 65 to which the connecting member 64 is fastened moves in the width direction, and the roller support portion 66 moves in the width direction. As a result, the registration driving roller 18a and the relay driving roller 43a supported by the roller supporting portion 66 move in the width direction, and the sheet sandwiched between the relay roller pair 43 and the registration roller pair 18 is shifted in the width direction. You can

When the registration driving roller 18a and the relay driving roller 43a are located at the home position, the connecting member 64 extends between the shift driving pulley 65b of the shift timing belt 63 and the shift driven pulley 62, as shown in FIG. It is located in the center of the rack area. Accordingly, the roller support portion 66 can be moved to both the one side (front side of the device) and the other side (back side of the device) in the width direction.

In the present embodiment, the shift mechanism 60 moves the relay drive roller 43a and the registration drive roller 18a in the width direction. However, the shift mechanism 60 moves the relay drive roller 43a in the width direction and the registration drive roller 18a in the width direction. You may respectively provide the shift mechanism which moves to a direction.

The relay driven roller 43b and the registration driven roller 18b are also configured to be movable in a predetermined range in the width direction (axial direction), and the shift mechanism 60 moves the registration driving roller 18a and the relay driving roller 43a in the width direction (axial direction). In doing so, the relay driven roller 43b and the registration driven roller 18b may be configured to move in the width direction following the movement. Accordingly, when the paper is shifted in the width direction, the relay driven roller 43b and the registration driven roller 18b can be moved in the width direction together with the paper, and the movement resistance of the paper in the width direction can be reduced. Therefore, the position in the width direction of the paper can be accurately aligned with the target position.

FIG. 11 is a block diagram showing an example of a main configuration of a control system in the shift device 50 according to the present embodiment.
As shown in FIG. 11, the paper detection sensor 46, the torque detection sensor 201, the shift drive unit 61 of the shift mechanism, the roller drive device 90, the guide drive device 130, etc. are connected to the control unit 200.

The control unit 200 calculates the difference between the position in the width direction of the sheet detected by the sheet detection sensor 46 and the target position stored in the storage unit included in the control unit 200, and based on the difference value, the shift amount. (Correction amount) is calculated. If the shift motor 65 of the shift driving unit 61 is a stepping motor, the number of pulses is calculated as the shift amount based on the difference value. If the shift motor 65 is a DC motor, the drive time of the motor is calculated as the shift amount based on the difference value. Further, the control unit 200 determines the rotation direction of the shift motor 65 based on whether the difference value is positive or negative.

Further, the control unit 200 controls the guide driving device 130 to move the upstream guide unit 51a and the downstream guide unit 51b from the guide position to the separated position, and then starts the shift operation. Further, the control unit 200 controls the roller driving device 90 so that the sheet conveying speed V1 of the registration roller pair 18 is faster than the sheet conveying speed V2 of the relay roller pair 43 to convey the sheet. Then, the paper feed speed V2 of the relay roller pair 43 is feedback-controlled based on the detection value of the torque detection sensor so that the detection value of the torque detection sensor 201 becomes substantially zero.

Further, in the control unit 200, the inner guide member 51 (the upstream guide unit 51a and the downstream guide unit 51b) moves to the separated position, and the bending of the paper between the relay roller pair 43 and the registration roller pair 18 occurs. The shift driving unit 61 is controlled to start the shift operation at the canceled timing. The above timing can be obtained in advance by experiments or the like. The inner guide member reaches the separated position and bends the paper at a stage before the front end of the paper reaches the secondary transfer so that the shift operation is completed before the front end of the paper reaches the secondary transfer nip. In order to eliminate the above, the moving speed of the inner guide member 51 from the guide position to the separated position and the speed difference between the relay roller pair 43 and the registration roller pair 18 are determined.

Further, when the torque detection sensor 201 detects an increase in torque, the shift operation may be started. Even with such a configuration, the shift operation can be performed when the bending of the sheet between the relay roller pair 43 and the registration roller pair 18 is eliminated.

FIG. 12 is a control flow chart of the shift operation in the shift device 50.
As shown in FIG. 12, as the initial position, the upstream guide portion 51a and the downstream guide portion 51b are positioned at the guide position and the inner guide member 51 is positioned at the guide position (S21). Further, the registration drive roller 18a and the relay drive roller 43a are located at the center home position in the movement range in the width direction.

First, the registration roller pair 18 is stopped, and only the relay roller pair 43 is rotationally driven to convey the fed paper to the registration roller pair 18, and the leading end of the paper is abutted against the stationary registration roller pair 18. (S1). Then, when the relay roller pair 43 is excessively fed, the sheet is bent between the relay roller pair 43 and the registration roller pair 18 to perform skew correction of the sheet (S2), and then the rotation of the relay roller pair 43 is stopped. (S3).

Next, the control unit 200 determines a predetermined timing (a timing when the toner image on the intermediate transfer belt 16 reaches the secondary transfer nip, a timing when the sheet conveyed by the registration roller pair enters the secondary transfer nip). The registration roller pair 18 and the relay roller pair 43 are rotationally driven at a timing (S4) (S4). Further, at this time, the control unit 200 controls the roller driving device 90 so that the sheet conveying speed V1 of the registration roller pair 18 becomes faster than the sheet conveying speed V2 of the relay roller pair 43 (S5). As a result, the sheet is conveyed to the secondary transfer nip while the sheet bending between the relay roller pair 43 and the registration roller pair 18 is eliminated.

Further, the control unit 200 monitors the detection value of the torque detection sensor 201 and feedback-controls the sheet conveyance speed of the relay roller pair 43 so that the torque of the registration drive roller is maintained at almost zero. Accordingly, it is possible to prevent the sheet from being excessively pulled between the registration roller pair 18 and the relay roller pair 43.

Next, the control unit 200 controls the guide driving device 130 to rotate the upstream guide unit 51a and the downstream guide unit 51b from the guide position to the separated position, and separates the inner guide member 51 from the guide position. It is retracted to the position (S22). As a result, even if the paper is pulled between the relay roller pair 43 and the registration roller pair 18, the paper does not come into contact with the inner guide member 51.

Next, the leading edge of the conveyed sheet passes the sheet detection sensor 46, and the position in the width direction of the sheet is detected. When the paper detection sensor 46 detects the position in the paper width direction, the control unit 200 calculates the difference between the paper width direction position detected by the paper detection sensor 46 and the target position, and shifts based on the difference value. (Correction amount) and shift direction are calculated (S7).

Next, the control unit 200 controls the shift drive unit 61 based on the calculated shift amount and shift direction to move the registration drive roller 18a and the relay drive roller 43a in the predetermined direction in the width direction, A shift operation for shifting the paper in the width direction is executed (S8).

During this shift operation, the bending of the sheet between the relay roller pair 43 and the registration roller pair 18 is eliminated, and the sheet is pulled as shown in FIG. 4B. Further, the inner guide members (the upstream guide portion 51a and the downstream guide portion 51b) are located at the separated position. As a result, the paper is not in contact with the outer guide member 52, and the inner guide member 51 is not in contact with the inner guide member 51 because it is retracted to the separated position. As a result, it is possible to suppress the occurrence of sliding resistance on the paper during the shift operation, and it is possible to accurately shift the paper to the target position. The speed of shifting in the width direction of the sheet is set so that the shift to the target position is completed before the leading edge of the sheet reaches the secondary transfer nip.

When the shift operation is completed (S9), the control unit 200 controls the guide driving device 130 to rotate the upstream guide unit 51a and the downstream guide unit 51b from the separated position to the guide position, and the inner guide member 51. Is returned from the separated position to the guide position (S23). At this time, if the trailing edge of the sheet does not pass through the relay roller pair 43, the sheet may come into contact with the inner guide member 51 and the conveyance resistance may increase. However, in the present embodiment, as described above, the detection value of the torque detection sensor 201 is monitored, and the paper feed speed V2 of the relay roller pair 43 is feedback-controlled so that the torque of the registration drive roller 18a is maintained at substantially zero. doing. Therefore, when the sheet comes into contact with the inner guide member 51 to increase the conveyance resistance and the torque of the registration driving roller 18a increases, the sheet conveyance speed V2 of the relay roller pair 43 increases accordingly. As a result, the sheet conveyance speed V2 of the relay roller pair 43 becomes faster than the sheet conveyance speed V1 of the registration roller pair 18 (V2>V1), and the relay roller pair 43 and the registration roller pair 43 follow the curved shape of the inner guide member 51. The paper between 18 can be deflected. As a result, even if the inner guide member 51 is returned to the guide position in the state where the trailing edge of the sheet has not passed through the relay roller pair 43, the sheet resistance can be smoothly conveyed without an excessive increase in conveyance resistance. ..

Then, after a lapse of a predetermined time after the sheet reaches the secondary transfer roller (secondary transfer nip), which is a conveyance roller on the downstream side of the registration roller pair 18 in the conveyance direction, the trailing edge of the sheet moves to the registration roller pair 18. At the timing of the removal, the rotational driving of the registration roller pair 18 and the relay roller pair 43 is stopped (S10). Then, the shift drive unit 61 is controlled to move the registration drive roller 18a and the relay drive roller 43a in the opposite direction to that during the shift operation, and prepare for the next sheet feeding (S11). ..

What has been described above is an example, and the following unique effects can be obtained.
(Aspect 1)
At least one of the pair of transport members is movable in the width direction, which is a direction orthogonal to the sheet transport direction, and the first shift transport member pair such as the registration roller pair 18, and the first shift transport member pair that is closer to the sheet transport direction than the first shift transport member pair. A second shift conveying member pair such as a relay roller pair 43, which is arranged on the upstream side and at least one of the pair of conveying members is movable in the width direction, and a second shift conveying member pair and a first shift conveying member pair. In a shift device 50 that is disposed between and includes a guide member such as an inner guide member 51 that guides a sheet such as a sheet of paper P, a guide driving device 130 that separates the guide member from a guide position that guides the sheet. Prior to the shift operation for shifting the position of the sheet in the width direction, the separating member separates the guide member from the guide position, and the sheet conveying speed of the first shift conveying member pair is set to the second shift conveying member pair. The sheet is conveyed at a speed higher than the sheet conveying speed of.
In the shift device described in Patent Document 1, the sheet is shifted in the width direction while being conveyed while the sheet is bent by a predetermined amount between the first shift conveying member pair and the second shift conveying member pair. Therefore, the bent portion of the sheet may come into contact with the guide member between the first shift conveying member pair and the second shift conveying member pair. As described above, when the sheet is shifted in the width direction while the sheet is in contact with the guide member, the contact portion of the sheet with the guide member slides on the guide member, which becomes a resistance against the shift in the sheet width direction. As a result, the sheet may not be shifted to the target position in the width direction, and the sheet may not be accurately shifted to the target position in the width direction.
On the other hand, in the aspect 1, the guide member is separated from the guide position and the guide member is separated from the sheet prior to the start of the shift operation for shifting the sheet in the width direction. As a result, contact between the guide member and the sheet can be prevented during the shift operation, and the widthwise position of the sheet can be accurately shifted to the target position.
Further, prior to the shift operation, the sheet is conveyed by setting the sheet conveying speed of the first shift conveying member pair to be higher than the sheet conveying speed of the second shift conveying member pair, and during the shift operation, the sheet is conveyed to the first shift conveying member pair. The bending of the sheet between the second shift conveyance member and the second shift conveyance member is almost eliminated. As a result, the sheet posture between the second shift conveyance member pair and the first shift conveyance member pair during the shift operation is determined to be substantially straight. Therefore, it is sufficient to separate only the guide member (in this embodiment, the inner guide member 51) that may come into contact with the sheet in a state where the sheet is substantially straight, and it is possible to reduce the number of guide members to be separated. This makes it possible to simplify the device configuration. Further, since the posture is fixed, the minimum amount of separation of the guide member from the guide position where the sheet does not contact the guide member can be easily grasped, and the amount of separation of the guide member can be suppressed. As a result, the space for separating the guide members can be reduced, and the space of the device can be saved.

(Aspect 2)
In Aspect 1, in the sheet conveyance path between the second shift conveyance member pair such as the relay roller pair 43 and the first shift conveyance member pair such as the registration roller pair 18, the sheet is curved to the first shift conveyance member pair. The first shift conveyance member pair hits the leading end of the conveyed sheet, and the sheet is bent by a predetermined amount between the second shift conveyance member pair and the first shift conveyance member pair. After that, the sheet is conveyed.
According to this, as described in the embodiment, the sheet conveyance path between the second shift conveyance member pair such as the relay roller pair 43 and the first shift conveyance member pair such as the registration roller pair 18 has a curved shape. As a result, it is possible to arrange the shift device 50 without increasing the size of the device in which the shift device 50 is mounted and reducing the specifications, as compared with the case of the linear shape.
Further, as described in the embodiment, the sheet conveyance path between the second shift conveyance member pair and the first shift conveyance member pair has a curved shape, and the second shift conveyance member pair and the first shift conveyance member pair are Since the sheet is bent by a predetermined amount between the two, it is easy for the sheet to contact the guide member, and it is difficult to accurately position the sheet at the target position.
However, by providing the configuration of the first aspect, it is possible to effectively position the sheet in the width direction at the target position.

(Aspect 3)
In the second aspect, the guide member separated by the separating unit such as the guide driving device 130 is a guide member such as the inner guide member 51 arranged inside the curved conveyance path.
According to this, as described in the embodiment, the sheet conveying speed of the first shift conveying member pair is made higher than the sheet conveying speed of the second shift conveying member pair, and the second shift conveying member pair and the second shift conveying member pair are conveyed. When the bending of the sheet between the pair of conveying members is eliminated, the sheet between them approaches the guide member such as the inner guide member 51. Therefore, by separating the guide member arranged inside the curved conveyance path from the guide position, it is possible to prevent the sheet from coming into contact with the guide member.

(Aspect 4)
In any one of Modes 1 to 3, the guide member such as the inner guide member 51 is divided into a plurality of pieces in the sheet conveying direction (in this embodiment, the upstream guide portion 51a and the downstream guide portion 51b are divided into two). ..
According to this, as described in the embodiment, the movement amount of the guide member on the other end side is reduced as compared with the case where one end of the undivided guide member is rotated to move from the guide position to the separated position. It is possible to move from the guide position to the retracted position in a space-saving manner.

(Aspect 5)
In any one of modes 1 to 4, a torque detection unit such as a torque detection sensor 201 that detects a torque of the first shift conveyance member pair such as the registration roller pair 18 or the second shift conveyance member pair such as the relay roller pair 43 is provided. The speed difference between the first shift conveyance member pair and the second shift conveyance member pair is changed based on the torque detection result of the torque detection means.
According to this, as described in the embodiment, it is possible to prevent the sheet between the second shift conveyance member pair such as the relay roller pair 43 and the first shift conveyance member such as the registration roller pair 18 from being excessively pulled. can do.

(Aspect 6)
In the fifth aspect, the first shift conveyance member pair such as the registration roller pair 18 and the second shift conveyance such as the relay roller pair 43 are set so that the detection value of the torque detection means such as the torque detection sensor 201 maintains a predetermined value. Change the speed difference between the member pair.
According to this, as described in the embodiment, the tension state of a sheet such as a sheet between the second shift conveyance member pair such as the relay roller pair 43 and the first shift conveyance member such as the registration roller pair is set to a predetermined value. It is possible to maintain the state, and it is possible to prevent the paper between the second shift conveying member pair and the first shift conveying member from being excessively pulled.

(Claim 7)
A sheet conveying apparatus including a shift device such as a shift device 50 that shifts a conveyed sheet in a width direction that is a direction orthogonal to the sheet conveying direction. The sheet conveying device includes the shift device according to any one of aspects 1 to 6 as the shift device. ..
According to this, as described in the embodiment, the position in the sheet width direction can be accurately shifted to the target position.

(Claim 8)
An image forming apparatus including a sheet conveying unit configured to convey a sheet and an image forming unit configured to form an image on the sheet conveyed by the sheet conveying unit includes the sheet conveying apparatus according to the seventh aspect as the sheet conveying unit.
According to this, it is possible to suppress the positional deviation of the image formed on the sheet in the width direction.

18: registration roller pair 18a: registration driving roller 18b: registration driven roller 43: relay roller pair 43a: relay driving roller 43b: relay driven roller 46: sheet detection sensor 50: shift device 51: inner guide member 51a: upstream guide portion 51b: Downstream guide part 52: Outer guide member 60: Shift mechanism 61: Shift drive part 62: Shift driven pulley 63: Shift timing belt 64: Connecting member 65: Shift motor 65a: Motor shaft 65b: Shift drive pulley 66: Roller Support part 66a: Front side plate 66b: Back side plate 67: Fixed plate 70: Relay drive part 71: Relay motor 72: Timing belt 72a: Driving pulley 72b: Driven pulley 80: Registration drive part 81: Registration motor 82: Timing belt 82a: drive pulley 82b: driven pulley 90: roller drive device 91: common motor 92: timing belt 93: first timing belt 94: transmission 95: second timing belt 100: printer 110: first guide drive unit 111: first 1 guide motor 112: 1st guide timing belt 120: 2nd guide drive part 121: 2nd guide motor 122: 2nd guide timing belt 130: Guide drive device 131: Common guide motor 200: Control part 201: Torque detection sensor V1 : Paper transport speed of registration roller pair V2: Paper transport speed of relay roller pair

Japanese Patent No. 6010861

Claims (8)

At least one of the pair of conveying members is a first shift conveying member pair movable in the width direction which is a direction orthogonal to the sheet conveying direction,
A second shift conveyance member pair that is arranged on the upstream side in the sheet conveyance direction with respect to the first shift conveyance member pair, and at least one of a pair of conveyance members is movable in the width direction,
In a shift device provided between the second shift conveyance member pair and the first shift conveyance member pair, and a guide member for guiding a sheet,
The guide member is provided with a separating means for separating from the guide position for guiding the sheet,
Prior to the shift operation for shifting the sheet in the width direction, the separating member separates the guide member from the guide position, and the sheet conveying speed of the first shift conveying member pair is set to the second shift conveying member pair. A shift device, which transports a sheet at a speed higher than the sheet transport speed of. The shift device according to claim 1,
The sheet transport path between the second shift transport member pair and the first shift transport member pair is a curved transport path in which a sheet is curved and goes toward the first shift transport member pair.
The first shift conveying member pair conveys the sheet after the leading edge of the conveyed sheet hits and the sheet is bent by a predetermined amount between the second shift conveying member pair and the first shift conveying member pair. A shift device characterized by: The shift device according to claim 2,
The shift device characterized in that the guide member separated by the separating means is a guide member arranged inside a curved conveyance path. The shift device according to any one of claims 1 to 3,
The shift device is characterized in that the guide member is divided into a plurality in the sheet conveying direction. The shift device according to any one of claims 1 to 4,
A torque detecting means for detecting a torque of the first shift conveying member pair or the second shift conveying member pair;
A shift device characterized by changing a speed difference between the first shift conveying member pair and the second shift conveying member pair based on a torque detection result of the torque detecting means. The shift device according to claim 5,
The shift device, wherein the speed difference between the first shift conveying member pair and the second shift conveying member pair is changed so that the detection value of the torque detecting means maintains a predetermined value. In a sheet conveying device provided with a shift means for shifting the conveyed sheet in a width direction which is a direction orthogonal to the sheet conveying direction,
A sheet conveying apparatus comprising the shift device according to claim 1 as the shift unit. Sheet conveying means for conveying a sheet,
In an image forming apparatus including an image forming unit that forms an image on a sheet conveyed by the sheet conveying unit,
An image forming apparatus comprising the sheet conveying device according to claim 7 as the sheet conveying means.

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