JP7137789B2 - Shift device, sheet conveying device and image forming device - Google Patents

Description

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

Conventionally, a pair of first shift conveying members in which at least one of the pair of conveying members is movable in the width direction, which is a direction perpendicular to the sheet conveying direction, is arranged upstream of the pair of first shift conveying members in the sheet conveying direction. a pair of second shift conveying members in which at least one of the pair of conveying members is movable in the width direction; and a guide member disposed between the pair of second shift conveying members and the first pair of shift conveying members for guiding the sheet. is known.

Japanese Patent Laid-Open No. 2004-100002 discloses a shift device in which the leading edge of a sheet is brought into contact with a first pair of shift conveying members, and after bending the sheet by a predetermined amount between the first pair of shift conveying members and the second pair of shift conveying members. , start conveying the sheet by the first pair of shift conveying members. Then, the conveying members of the first pair of shift conveying members and the conveying members of the second pair of shift conveying members are moved in the width direction while the sheet is sandwiched between the pair of first shift conveying members and the pair of second shift conveying members. and shift the position of the sheet in the width direction to a target position.

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

In order to solve the above-described problems, the present invention provides a first shift conveying member pair in which at least one of a pair of conveying members is movable in a width direction perpendicular to the sheet conveying direction, and the first shift conveying member pair. a second shift conveying member pair arranged upstream of the pair of members in the sheet conveying direction, at least one of a pair of conveying members being movable in the width direction; and a guide member arranged between a pair of shift conveying members to guide a sheet, further comprising separating means for separating the guide member from a guide position for guiding the sheet, wherein the sheet is moved in the width direction. the guide member is separated from the guide position by the separating means, and the sheet conveying speed of the first pair of shift conveying members is set higher than the sheet conveying speed of the second pair of shift conveying members. It is characterized in that the sheet is conveyed at a higher speed.

According to the present invention, the position of the sheet in the width direction can be shifted to the target position with high accuracy.

1 is a schematic configuration diagram of a printer according to the embodiment; FIG. The schematic diagram which shows an example of the conventional shift apparatus. FIG. 10 is a diagram showing an example of a state of a sheet between a pair of relay conveying rollers and a pair of registration rollers 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 apparatus of this embodiment. FIG. 4 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. The schematic diagram which shows the modification of a guide drive device. 3 is a perspective view of a shift mechanism; FIG. FIG. 2 is an enlarged perspective view of a main portion of a shift driving portion; FIG. 2 is a block diagram showing an example of a main configuration of a control system in the shift device according to the present embodiment; FIG. 4 is a control flow diagram of a shift operation in the 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 equipped with a sheet conveying device according to the present invention. In this embodiment, a color laser printer will be described as an example of an image forming apparatus. image forming apparatus. Further, the image forming apparatus provided with the sheet conveying device according to the present invention is not limited to the electrophotographic method, and may be an image forming apparatus of other methods such as an inkjet method.

FIG. 1 is a schematic configuration diagram of a printer 100 according to this embodiment.
The printer 100 is provided with an intermediate transfer belt 16 substantially in the center of the printer main body 1 . Four image forming units 2 (Y, M, C, 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 image forming units will be explained here by omitting the reference numerals indicating colors.

The image forming unit 2 includes a photoreceptor 12, which is a latent image carrier facing a stretched surface above an intermediate transfer belt 16. Around the photoreceptor 12, a charging device 11, which is a charging means, is provided. A laser scanning unit 10 as means, a developing device 13 as developing means, and the like are provided. A primary transfer roller 14 facing the photosensitive member 12 with the intermediate transfer belt 16 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 facing roller 16a facing the secondary transfer roller 15 across the intermediate transfer belt 16 is provided to form a secondary transfer nip. .
At the bottom of the printer main body 1, there is provided a paper feeding device 20 which is a sheet conveying device in which three paper feeding trays 5 from the first to the third can be pulled out from the main body of the printer. , a transfer sheet, a resin film, or the like, are accommodated.

When the printer 100 starts printing, the photoreceptor 12 is rotated counterclockwise in FIG. 1, and the intermediate transfer belt 16 is rotated clockwise in FIG. At this time, the charging device 11 uniformly charges the surface of the photosensitive member 12 to a predetermined polarity. Next, the surface of the uniformly charged photoreceptor 12 is irradiated with laser light based on image information from the laser scanning unit 10 for each color, thereby forming an electrostatic latent image on the photoreceptor 12 . The electrostatic latent image formed on the surface of the photoreceptor 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. . A photoreceptor cleaning device removes transfer residual toner adhering to the surface of the photoreceptor 12 after the toner image is transferred.

When forming a color image, the image forming operation described above is performed in all the image forming units 2, whereby the yellow toner image, the cyan toner image, the magenta toner image, and the black toner image respectively formed on the individual photoreceptors 12 are intermediate images. The images are successively transferred onto the transfer belt 16 in an overlapping manner.

On the other hand, the paper P is fed from the paper feeding device 20 . By using the operation panel 3 or an input terminal such as a personal computer, the user selects the paper feed tray 5 to be used from the three paper feed trays 5, and the paper P stored in the selected paper feed tray 5 is displayed. Paper is fed.
A dashed line indicated by reference numeral "19" in FIG.

The fed paper P is sent out toward the registration roller pair 18, and the front end of the paper P abuts against the registration roller pair 18 which is stopped.
After the paper P is thus aligned, the registration roller pair 18 feeds the paper P toward the secondary transfer nip at a timing that matches the toner image on the intermediate transfer belt 16 . An intermediate transfer belt cleaning device removes transfer residual toner adhering to the surface of the intermediate transfer belt 16 after the toner image is transferred at the secondary transfer nip.

The paper P to which the unfixed toner image has been transferred by the secondary transfer nip is sent to the fixing device 17, and after the unfixed toner image is fixed on the paper P, it is discharged to the paper discharge tray 4 in the case of single-sided printing. be.
In the case of double-sided printing, the paper P with an image formed on the first side is conveyed to the double-sided path by switching the conveying path with the branch claw 40 . The sheet P sent out to the reversing roller pair 41 by the branching claw 40 is transported 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 paper P with respect to the transport direction are reversed from those during image formation on the first surface. After the paper P is conveyed to the relay roller pair 43 and the registration roller pair 18, the image is formed on the second surface in the same process as described above, and then the paper P is discharged to the paper discharge tray 4.

The user can optionally connect a paper supply bank capable of supplying a large amount of paper P to the printer main body 1 and a finisher capable of stapling and folding instead of the paper output tray 4 .

Further, in the present embodiment, the paper is shifted in the width direction to the upstream side in the paper transport direction from the secondary transfer nip, the positional deviation of the fed paper in the width direction is corrected, and the image position on the paper is aligned. A device 50 is provided. The shift device 50 of this embodiment includes a registration roller pair 18 as a first shift conveying member pair and a relay roller pair 43 as a second shift conveying member pair. In the form, 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 width direction edge of the paper is provided on the downstream side of the registration roller pair 18 in the paper transport direction.

The fed paper is conveyed to the registration roller pair 18 via the relay roller pair 43 . The leading edge of the paper collides with the stationary registration roller pair 18, and the paper P is bent between the relay roller pair 43 and the registration roller pair 18, and after the skew is corrected, the registration roller pair 18 is rotated to convey the paper. For the paper P transported by the pair of registration rollers 18 , the width direction edge position of the paper is detected by the paper detection sensor 46 . Based on the width direction edge position of the paper detected by the paper detection sensor 46 and the target position stored in advance in the storage means, the shift amount (correction amount) in the width direction of the paper is determined, and the shift is performed. Based on the amount, a shift operation is performed to shift the position of the sheet in the width direction to the target position. As a result, the paper can be transported to the secondary transfer nip with the width direction position of the paper positioned at the target position, and the image can be transferred to 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 immovable in the width direction. Then, one of the transport roller pairs (relay roller pair 43 and vertical transport roller pair 44) holding the paper is separated from the other transport 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 paper P between the relay roller pair 43 and the registration roller pair 18 during the shift operation of shifting the position of the paper in the width direction in the conventional shift device.
As described above, the leading edge of the sheet conveyed to the registration roller pair 18 collides with the stopped registration roller pair 18 and forms a predetermined deflection between the relay roller pair 43 and the registration roller pair 18 to cause skew. making corrections. At this time, the bending of the paper differs depending on the state of the paper (the rigidity and curling of the paper). Therefore, as indicated by the dotted line S in FIG. 3A, there are cases 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 is brought into contact. , and when contacting both the outer guide member 52 and the inner guide member 51 as indicated by dotted lines S1 and S2 in FIG. Different ways of contact.

When the paper is shifted in the width direction while it is in contact with the inner guide member 51 and the outer guide member 52, the paper rubs against the outer guide member 52 and the inner guide member 51, and the rubbing occurs. It acts as a resistance when shifting the paper P in the width direction. Since the state of contact between the paper and the guide members 51 and 52 differs depending on the state of the paper as described above, the resistance when shifting the paper P in the width direction also differs depending on the state of the paper. As a result, depending on the state of the paper, the paper P may not be shifted to the target position, and the image may not be transferred to the target position on the paper P.

In addition, due to sliding resistance, the paper is twisted between the intermediate roller pair 43 and the registration roller pair 18, and the twisted paper is sandwiched between the registration roller pair, which may cause damage such as wrinkles on the paper. There is also

As shown in FIG. 3, when the shift operation is performed, the intermediate roller pair 43 is moved away from the intermediate roller pair 43 to eliminate the bending of the paper between the intermediate roller pair 43 and the registration roller pair 18. The behavior of the paper is not stable, and there is a risk that the paper will come into contact with the guide member, making it impossible to shift the paper P to the target position.

If the conveying path from the relay roller pair 43 to the registration roller pair 18 is curved, the paper is bent and reaches the registration roller pair 18 . Therefore, during the shift operation, the paper easily abuts against 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 conveying path from the intermediate roller pair 43 to the registration roller pair 18 linear. By making the conveying path straight from the relay roller pair 43 to the registration roller pair 18, the behavior of the paper is stabilized when the rollers of the relay roller pair are separated from each other as compared with the case where the conveying path has a curved shape. It is possible to suppress contact with the guide member. However, it is necessary to secure a space for linear transport in the apparatus, which may increase the size of the printer. It is also conceivable to eliminate the manual feed tray, reduce the number of paper feed trays, or reduce the number of paper feed trays to secure a space that enables straight transport without increasing the size of the printer. There is a problem that the specs of are dropped.

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 this may lead to an increase in cost due to an increase in the number of parts. In addition, when attaching the slidable sheet 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 the guide member, which may lead to an increase in the cost of the device. There is also Furthermore, with use over time, the portions of the sliding sheet that rub against the paper may disappear due to wear, making it impossible to ensure slidability over time. Moreover, even with such a configuration, since the sheet slides on the guide member during the shift operation, the sliding resistance cannot be reduced to zero, and a highly accurate shift operation cannot be completely realized.

Also, when shifting the paper in the width direction, it is conceivable to move both the outer guide member 52 and the inner guide member 51 away from the guide positions shown in FIG. 3 so that they do not come into 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. In addition, 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 sheet bends and the behavior of the sheet during transport differs depending on the state of the sheet, in order to prevent the sheet from coming into contact with the guide members, it is necessary to separate the guide members greatly for safety. There is also a risk that it will lead to an increase in the size of the

Therefore, in the present embodiment, the sheet conveying speed of the registration roller pair 18 is made faster than the sheet conveying speed of the relay roller pair 43 to eliminate 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 come into contact with the guide member, and then the shift operation is performed.

FIG. 4 is a schematic diagram showing the shift device 50 of this embodiment.
In this embodiment, both the registration roller pair 18 and the intermediate roller pair 43 are provided with rollers movable in the width direction. Also, the inner guide member 51 is divided into an upstream guide portion 51a and a downstream guide portion 51b. The upstream guide portion 51a is rotatably supported at its upstream end, 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 end portion of the downstream guide portion 51b is 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 be retracted from the paper guide position.

As shown in FIG. 4B, before the shift operation for correcting the position of the sheet P in the width direction, the sheet conveying speed V1 of the registration roller pair 18 is made faster than the sheet conveying speed V2 of the relay roller pair 43. (V1>V2). By conveying the paper with a speed difference in this way, the warped paper between the relay roller pair 43 and the registration roller pair 18 is straightened and pulled. Therefore, during the shift operation, the sheet between the relay roller pair 43 and the registration roller pair 18 is in a straight posture along the line connecting the nip of the relay roller pair and the registration roller pair. Determined. As a result, even if the posture of the paper when the skew is corrected by abutting the leading edge of the paper against the pair of registration rollers varies depending on the state of the paper, the posture shown in FIG. 4B can always be maintained during the shift operation. . As a result, the paper can be reliably separated from the outer guide member 52 during the shift operation.

Further, as the bending of the sheet between the relay roller pair 43 and the registration roller pair 18 is eliminated, the sheet moves toward the inner guide member 51 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 indicated by the dashed line in FIG. 4B to the separated position indicated by the solid line in the figure. Let This can also prevent the sheet from contacting the inner guide member 51 . As a result, it is possible to prevent the paper from rubbing against the outer guide member 52 and the inner guide member 51 during the shift operation.

As a result, during the shift operation, the paper is smoothly shifted in the width direction without receiving sliding resistance, and the position of the paper in the width direction can be accurately positioned at the target position. Moreover, the paper between the relay roller pair and the registration roller pair is not twisted due to the sliding resistance with the guide member, and wrinkles and the like can be suppressed from occurring in the paper.

Further, in this embodiment, the posture of the sheet between the relay roller pair 43 and the registration roller pair 18 during the shift operation is determined as shown in FIG. If only the inner guide member 51 is configured to be 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 a 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 sheet 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 sheet do not come into contact with each other. can be grasped. As a result, contact between the inner guide member 51 and the sheet can be prevented with a minimum required amount of movement, and the movement space of the inner guide member 51 can be reduced, thereby achieving space saving.

Further, in the present embodiment, even if the conveying path between the relay roller pair 43 and the registration roller pair 18 has a curved shape, the sheet P can be shifted in the width direction with high accuracy. As a result, it is possible to accurately shift the paper P 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. As a result, compared to 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 moved from the guide position to the separated position. It is possible to greatly reduce the amount of movement of the other end to . As a result, the space required for moving the inner guide member 51 from the guide position to the separated position can be narrowed compared to the case where the inner guide member 51 is not divided, and the increase in size of the device can be suppressed.

FIG. 5 is a schematic diagram of a roller drive device 90 that drives the registration roller pair 18 and the relay roller pair 43. As shown in FIG.
The roller drive device 90 includes a registration drive section 80 that drives the registration roller pair 18 and a relay drive section 70 that drives the relay roller pair 43 . The registration drive unit 80 includes a registration motor 81, and a timing belt 82 that spans 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 section 70 has the same configuration as the registration drive section 80 . That is, it has a timing belt 72 that spans 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, and the control unit 200 controls the sheet conveying speed V1 of the registration roller pair 18 to be faster than the sheet conveying speed V2 of the relay roller pair 43. controlled. Before the start of the shift operation to shift the position of the paper in the width direction, the paper transport speed of the registration roller pair 18 and the relay roller pair 43 are adjusted so that the paper between the registration roller pair 18 and the relay roller pair 43 is pulled out. A speed difference (V1-V2) from the transport speed is set.

Further, the control unit 200 is provided with a torque detection sensor 201 for detecting the torque of the registration drive roller 18a. The control unit 200 feedback-controls the relay motor 71 so that the detection value of the torque detection sensor 201 is maintained at approximately 0 (the torque of the registration driving roller is approximately 0), and the sheet conveying speed V1 of the registration roller pair 18 is increased. , and the speed difference from the sheet conveying speed V2 of the relay roller pair 43 is adjusted.

In the present embodiment, as described above, the paper conveying speed V1 of the registration roller pair 18 is set higher than the paper conveying speed V2 of the relay roller pair 43 (V1>V2) to create a speed difference between the paper conveying speed V1 and the relay roller pair 43. The shift operation is started after the sheet is stretched out by removing the warping of the sheet between the pair of registration rollers 18.例文帳に追加However, even after the sheet between the relay roller pair 43 and the registration roller pair 18 has been overwhelmed by tension, if the speed difference is maintained, defects such as abnormal images and wrinkles will occur due to excessive tension. There is a risk of

Therefore, the control unit 200 uses the torque detection sensor 201 to detect an increase in the torque of the registration drive roller 18 a caused by the sheet being pulled 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 substantially zero. Specifically, when the torque increases, control is performed to increase the sheet conveying speed V2 of the relay roller pair 43 .

As a result, after the deflection of the paper between the relay roller pair 43 and the registration roller pair 18 is eliminated and the paper is pulled over, the difference in paper conveying speed between the relay roller pair 43 and the registration roller pair 18 is eliminated, and the paper is pulled too much. Therefore, it is possible to suppress the occurrence of image abnormalities and wrinkles on the paper.

Further, it is preferable to change only the sheet conveying speed V2 of the relay roller pair 43 based on the detection value of the torque detection sensor 201, and maintain the sheet conveying speed V1 of the registration roller pair 18 constant. By maintaining the sheet conveying speed V1 of the registration roller pair 18 constant, the conveying speed of the sheet 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 conveying speed V2 of the relay roller pair 43. You can change it. In this case, when the torque detection sensor 201 detects a decrease in torque, feedback control is performed to increase the sheet conveying speed V2 of the relay roller pair 43, so that the sheet between the relay roller pair 43 and the registration roller pair 18 is increased. can be prevented from being excessively pulled.

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

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

A 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 . A second timing belt 95 wound around a pulley provided on the shaft of the registration drive roller 18 a is wound around a transmission 94 . The transmission 94 is composed of a plurality of pulleys having different diameters and a changing means for changing the pulley around which the second timing belt 95 is wound. Alternatively, a continuously variable transmission mechanism may be used as the transmission.

Further, a clutch is provided in a driving force transmitting portion that transmits driving force to the registration driving roller 18a. By providing the clutch, when the leading edge of the paper is abutted against the pair of registration rollers 18 and the paper is deflected by a predetermined amount for skew correction, the clutch is disengaged to stop the driving of the registration driving roller 18a and the relay driving roller 18a. Only 43a is rotationally driven to convey the paper.

The control unit 200 is connected to the common motor 91 and the transmission 94, and when the torque detection sensor 201 detects an increase in torque, the driving speed of the common motor 91 is increased to increase the sheet conveying speed of the relay roller pair 43 to V2. speed up. In addition, it controls the transmission 94 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 paper between the relay roller pair 43 and the registration roller pair 18 is in a state of tension, the difference between the paper conveying speed of the relay roller pair 43 and the paper conveying speed of the registration roller pair 18 becomes almost zero. Excessive pulling can be suppressed.

Also, 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 so that the paper transport speed of the registration roller pair 18 is V1, and based on the detection result of the torque detection sensor 201, the transmission 94 is controlled to adjust the speed reduction ratio. is changed, the sheet conveying speed V2 of the relay roller pair is changed.

Next, the guide driving 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 diagram showing the guide driving device 130. As shown in FIG.
A guide driving device 130 as a separating means includes a first guide driving portion 110 that moves the upstream guide portion 51a of the inner guide member 51 and a second guide driving portion 120 that moves the downstream guide portion 51b.
The first guide driving portion 110 is stretched over a first guide motor 111, a driving pulley provided on the first guide motor, and a driven pulley provided on the rotation axis X2 of the upstream guide portion 51a. It is configured with a guide timing belt 112 .

The second guide drive section 120 has the same configuration as the first guide drive section 110, and is connected to the second guide motor 121, the drive pulley provided in the second guide motor, and the rotary shaft X1 of the downstream guide section 51b. A second guide timing belt 122 stretched around a driven pulley provided.

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

In the above description, the timing belt is used to transmit the driving force to the guide portions (the upstream guide portion 51a and the downstream guide portion 51b), but gears may be used to transmit the driving force to the guide portions. Alternatively, 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 modification of the guide driving device 130. As shown in FIG.
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 the guide position and the separated position.
In this modified example, the configuration for transmitting the driving force to the downstream guide portion 51b has the same configuration as in FIG. That is, the second guide timing belt 122 is stretched over a drive pulley provided on the common guide motor 131 and a driven pulley provided on the rotation shaft X1 of the downstream guide portion 51b.

On the other hand, the configuration for transmitting the driving force to the upstream guide portion 51a is such that 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 Thus, one motor can move the upstream guide portion 51a and the downstream guide portion 51b between the guide position and the separated position.

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 the shift driving section 61. As shown in FIG.
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 within a predetermined range in the width direction with respect to the main body of the printer, and a roller support portion 66. , and a shift drive unit 61 for moving in a predetermined range in the width direction.

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

The shift driving section 61 has a shift motor 65, and a motor shaft 65a of the shift motor 65 is provided so as to be orthogonal to the width direction (which is also the axial direction of the roller). A motor shaft 65a of the shift motor 65 is provided with a shift drive pulley 65b. A shift timing belt 63 is stretched between the shift drive pulley 65b and a shift driven pulley 62 which is spaced apart from the motor shaft 65a by a predetermined distance in the width direction and whose center of rotation is parallel to the motor shaft 65a. . A connecting member 64 fastened to a fixing plate 67 of a roller support 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 drive roller 18a and the relay drive roller 43a supported by the roller support portion 66 are moved 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. can be done.

When the registration driving roller 18a and the relay driving roller 43a are located at the home position, the connecting member 64, as shown in FIG. It is located in the center of the hanging area. As a result, the roller support portion 66 can be moved to both the one width direction side (device front side) and the other width direction side (device back side).

In this embodiment, the shift mechanism 60 moves the relay drive roller 43a and the registration drive roller 18a in the width direction. A shift mechanism for moving in the direction may be provided, respectively.

Further, the relay driven roller 43b and the registration driven roller 18b are also configured to be movable in the width direction (axial direction) within a predetermined range. The relay driven roller 43b and the registration driven roller 18b may also move in the width direction following the movement. As a result, when the paper is shifted in the width direction, the relay driven roller 43b and the registration driven roller 18b can also be moved in the width direction together with the paper, and the movement resistance in the width direction of the paper can be reduced. Therefore, the position in the width direction of the paper can be precisely adjusted to the target position.

FIG. 11 is a block diagram showing an example of the main configuration of the control system in the shift device 50 according to this embodiment.
As shown in FIG. 11, the control unit 200 is connected with 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, and the like.

The control unit 200 calculates the difference between the position in the width direction of the paper detected by the paper detection sensor 46 and the target position stored in the storage means provided in the control unit 200, and calculates the shift amount based on the difference value. (correction amount) is calculated. If the shift motor 65 of the shift drive unit 61 is a stepping motor, the number of pulses is calculated as the shift amount based on the difference value. Also, 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 portion 51a and the downstream guide portion 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 to make the sheet conveying speed V1 of the registration roller pair 18 faster than the sheet conveying speed V2 of the relay roller pair 43 to convey the sheet. Then, feedback control is performed on the sheet conveying speed V2 of the relay roller pair 43 based on the detection value of the torque detection sensor so that the detection value of the torque detection sensor 201 becomes approximately zero.

Further, the controller 200 moves the inner guide member 51 (the upstream guide portion 51a and the downstream guide portion 51b) to the separated position, and the bending of the sheet between the relay roller pair 43 and the registration roller pair 18 is stopped. At the timing when it is canceled, the shift driving section 61 is controlled to start the shift operation. The above timing can be determined in advance by experiments or the like. In order to complete the shift operation before the leading edge of the paper reaches the secondary transfer nip, the inner guide member reaches the separation position at a stage considerably before the leading edge of the paper reaches the secondary transfer, and the bending of the paper is prevented. The movement 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 so as to eliminate the above.

Alternatively, the shift operation may be started when the torque detection sensor 201 detects an increase in torque. Even with such a configuration, it is possible to perform the shift operation 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 diagram of the shift operation in the shift device 50. As shown in FIG.
As shown in FIG. 12, as an 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). Also, the registration drive roller 18a and the relay drive roller 43a are positioned at the home position in the center of the movement range in the width direction.

First, the registration roller pair 18 is stopped, and only the intermediate roller pair 43 is driven to rotate, conveying the fed paper to the registration roller pair 18, and hitting the leading edge of the paper against the stopped registration roller pair 18. (S1). Then, by overfeeding the relay roller pair 43, the paper is bent between the relay roller pair 43 and the registration roller pair 18, and after skew correction of the paper (S2), the rotation of the relay roller pair 43 is stopped. (S3).

Next, the control unit 200 controls predetermined timing (the timing when the toner image on the intermediate transfer belt 16 reaches the secondary transfer nip and the timing when the sheet conveyed by the pair of registration rollers enters the secondary transfer nip). ), the pair of registration rollers 18 and the pair of relay rollers 43 are rotationally driven (S4). 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 transported to the secondary transfer nip while the sagging of the sheet 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 conveying speed of the relay roller pair 43 so that the torque of the registration driving roller is maintained at approximately zero. As a result, it is possible to prevent the sheet from being excessively stretched 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 portion 51a and the downstream guide portion 51b from the guide position to the separated position, thereby separating the inner guide member 51 from the guide position. It is retracted to a 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. - 特許庁

Next, the leading edge of the transported paper passes through the paper detection sensor 46, and the position of the paper in the width direction is detected. When the paper detection sensor 46 detects the position in the paper width direction, the controller 200 calculates the difference between the width direction position of the paper detected by the paper detection sensor 46 and the target position, and determines the shift amount based on the difference value. (correction amount) and the shift direction are calculated (S7).

Next, based on the calculated shift amount and shift direction, the control unit 200 controls the shift drive unit 61 to move the registration drive roller 18a and the relay drive roller 43a in a 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. 4(b). In addition, the inner guide members (the upstream guide portion 51a and the downstream guide portion 51b) are positioned 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 retracted to the separated position, so it is not in contact with the inner guide member 51 either. 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 shift the paper to the target position with high accuracy. The speed of shifting in the width direction of the paper is set so that the shift to the target position is completed before the leading edge of the paper reaches the secondary transfer nip.

After the shift operation is completed (S9), the control unit 200 controls the guide driving device 130 to rotate the upstream guide portion 51a and the downstream guide portion 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 paper has not passed through the relay roller pair 43, the paper may come into contact with the inner guide member 51 and the transport resistance may increase. However, in the present embodiment, as described above, the detection value of the torque detection sensor 201 is monitored, and the sheet conveying speed V2 of the relay roller pair 43 is feedback-controlled so that the torque of the registration driving roller 18a is maintained at approximately 0. is doing. Therefore, when the paper comes into contact with the inner guide member 51 and the conveyance resistance increases, and the torque of the registration drive roller 18a increases, the paper conveyance speed V2 of the relay roller pair 43 increases accordingly. As a result, the sheet conveying speed V2 of the relay roller pair 43 becomes faster than the sheet conveying speed V1 of the registration roller pair 18 (V2>V1), and following the curved shape of the inner guide member 51, the relay roller pair 43 and the registration roller pair The paper between 18 can be flexed. As a result, even if the inner guide member 51 is returned to the guide position in a state where the trailing edge of the paper has not passed through the relay roller pair 43, the paper can be smoothly conveyed without an excessive increase in the conveyance resistance. .

Then, after a predetermined time has passed since the sheet reached the secondary transfer roller (secondary transfer nip), which is a conveying roller downstream of the registration roller pair 18 in the conveying direction, the trailing edge of the sheet passes through the registration roller pair 18 . At this timing, the registration roller pair 18 and relay roller pair 43 stop rotating (S10). Then, the shift drive unit 61 is controlled to move the registration drive roller 18a and the relay drive roller 43a in the direction opposite to that during the shift operation to return them to their home positions to prepare for the next paper feed (S11). .

What has been described above is only an example, and each of the following aspects has a unique effect.
(Aspect 1)
A pair of first shift conveying members such as a pair of registration rollers 18 in which at least one of the pair of conveying members is movable in the width direction perpendicular to the sheet conveying direction; A second shift conveying member pair, such as a relay roller pair 43, which is arranged upstream and at least one of the pair of conveying members is movable in the width direction, and the second shift conveying member pair and the first shift conveying member pair. In the shifting device 50 provided with a guide member such as an inner guide member 51 disposed between and guiding a sheet such as a sheet of paper P, a separation such as a guide driving device 130 that separates the guide member from the guide position that guides the sheet. means for separating the guide member from the guide position by the separating means prior to the shift operation for shifting the position of the sheet in the width direction, and increasing the sheet conveying speed of the first shift conveying member pair to that of the second shift conveying member pair. The sheet is conveyed faster 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 in a state where the sheet is bent by a predetermined amount between the first pair of shift conveying members and the second pair of shift conveying members. Therefore, the bent portion of the sheet may come into contact with the guide member between the first pair of shift conveying members and the second pair of shift conveying members. 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, thereby resisting the shift in the sheet width direction. As a result, there is a possibility that the sheet cannot be shifted to the target position in the width direction, and the sheet cannot be shifted to the target position in the width direction with high accuracy.
On the other hand, in mode 1, the guide member is separated from the guide position and 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 shifting operation, and the widthwise position of the sheet can be shifted to the target position with high accuracy.
Prior to the shift operation, the sheet is conveyed by setting the sheet conveying speed of the first shift conveying member pair higher than the sheet conveying speed of the second shift conveying member pair. The bending of the sheet between the second shift conveying member is almost eliminated. As a result, the sheet posture between the second pair of shift conveying members and the first pair of shift conveying members is determined to be substantially straight during the shift operation. Therefore, only the guide members (the inner guide member 51 in this embodiment) that may come into contact with the sheet need to be separated while the sheet is in a substantially straight state, and the number of separated guide members can be reduced. This makes it possible to simplify the device configuration. In addition, since the posture is fixed, the minimum separation amount of the guide member from the guide position at which the sheet does not come into contact with the guide member can be easily grasped, and the separation amount of the guide member can be suppressed. Thereby, the space for separating the guide members can be reduced, and the space saving of the apparatus can be achieved.

(Aspect 2)
In mode 1, the sheet conveying path between the second pair of shift conveying members such as the relay roller pair 43 and the first pair of shift conveying members such as the registration roller pair 18 is such that the sheet curves to the first pair of shift conveying members. The leading edge of the conveyed sheet abuts against the first shift conveying member pair, and the sheet is bent by a predetermined amount between the second shift conveying member pair and the first shift conveying member pair. After that, the sheet is conveyed.
According to this, as described in the embodiment, the sheet conveying path between the second shift conveying member pair such as the relay roller pair 43 and the first shift conveying member pair such as the registration roller pair 18 has a curved shape. As a result, compared to the case of a linear shape, it is possible to increase the size of the device on which the present shift device 50 is mounted and to arrange it without lowering the specifications.
Further, as described in the embodiment, the sheet conveying path between the second shift conveying member pair and the first shift conveying member pair is curved, and the second shift conveying member pair and the first shift conveying member pair Since the sheet is bent by a predetermined amount between the two, the sheet is likely to come into contact with the guide member, and it is difficult to accurately position the sheet at the target position.
However, by providing the configuration of aspect 1, the position of the sheet in the width direction can be effectively positioned at the target position.

(Aspect 3)
In mode 2, the guide member separated by the separating means such as the guide driving device 130 is a guide member such as the inner guide member 51 arranged inside the curved conveying path.
According to this, as described in the embodiment, the sheet conveying speed of the first shift conveying member pair is made faster 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 When the bending of the sheet between the pair of conveying members is eliminated, the sheet therebetween moves toward the guide member such as the inner guide member 51 . Therefore, by separating the guide member arranged inside the curved conveying path from the guide position, it is possible to prevent the sheet from coming into contact with the guide member.

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

(Aspect 5)
In any one of modes 1 to 4, torque detection means such as a torque detection sensor 201 for detecting the torque of the first shift conveying member pair such as the registration roller pair 18 or the second shift conveying member pair such as the relay roller pair 43 is provided, A speed difference between the first shift conveying member pair and the second shift conveying member pair is changed based on the torque detection result of the torque detecting means.
According to this, as described in the embodiment, excessive pulling of the paper between the second shift conveying member pair such as the relay roller pair 43 and the first shift conveying member such as the registration roller pair 18 is suppressed. can do.

(Aspect 6)
In aspect 5, the first shift conveying member pair such as the registration roller pair 18 and the second shift conveying member such as the intermediate roller pair 43 are arranged such that the detected value of the torque detection means such as the torque detection sensor 201 maintains a predetermined value. Change the speed difference between member pairs.
According to this, as described in the embodiment, the pulling state of the sheet such as paper between the second shift conveying member pair such as the relay roller pair 43 and the first shift conveying member such as the registration roller pair can be set to a predetermined state. state can be maintained, and excessive pulling of the sheet between the second shift conveying member pair and the first shift conveying member can be suppressed.

(Claim 7)
A sheet conveying apparatus having shift means such as a shift device 50 for shifting a conveyed sheet in a width direction that is perpendicular to the sheet conveying direction, wherein the shift means includes the shift device according to any one of modes 1 to 6. .
According to this, as described in the embodiment, the position in the sheet width direction can be shifted to the desired position with high accuracy.

(Claim 8)
In an image forming apparatus comprising sheet conveying means for conveying a sheet and image forming means for forming an image on the sheet conveyed by the sheet conveying means, the sheet conveying device according to aspect 7 is provided as the sheet conveying means.
According to this, it is possible to suppress misalignment in the width direction of the image formed on the sheet.

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: paper detection sensor 50: shift device 51: inner guide member 51a: upstream guide section 51b: Downstream side guide portion 52: Outer guide member 60: Shift mechanism 61: Shift driving portion 62: Shift driven pulley 63: Shift timing belt 64: Connecting member 65: Shift motor 65a: Motor shaft 65b: Shift driving pulley 66: Roller Supporting portion 66a : Front side plate 66b : Back side plate 67 : Fixed plate 70 : Relay drive unit 71 : Relay motor 72 : Timing belt 72a : Drive pulley 72b : Driven pulley 80 : Registration drive unit 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 driving unit 111: Second First guide motor 112 : First guide timing belt 120 : Second guide drive section 121 : Second guide motor 122 : Second guide timing belt 130 : Guide drive device 131 : Common guide motor 200 : Control section 201 : Torque detection sensor V1 : Paper transport speed V2 of registration roller pair : Paper transport speed of relay roller pair

Japanese Patent No. 6010861

Claims (8)

a pair of first shift conveying members in which at least one of the pair of conveying members is movable in a width direction perpendicular to the sheet conveying direction;
a second shift conveying member pair arranged upstream in the sheet conveying direction of the first shift conveying member pair, at least one of the pair of conveying members being movable in the width direction;
A shift device comprising a guide member disposed between the second pair of shift conveying members and the first pair of shift conveying members for guiding a sheet,
Separating means for separating the guide member from a guide position for guiding the sheet,
Prior to the shift operation for shifting the sheet in the width direction, the separating means separates the guide member from the guide position, and the sheet conveying speed of the first pair of shift conveying members is changed to that of the second pair of shift conveying members. A shift device characterized in that the sheet is conveyed at a speed higher than the sheet conveying speed of the shift device. In the shift device according to claim 1,
the sheet conveying path between the second pair of shift conveying members and the first pair of shift conveying members is a curved conveying path in which the sheet curves and heads toward the first pair of shift conveying members;
The first shift conveying member pair conveys the sheet after the leading edge of the conveyed sheet abuts 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: In the shift device according to claim 2,
The shift device, wherein the guide member separated by the separating means is a guide member arranged inside the curved conveying path. The shift device according to any one of claims 1 to 3,
The shift device, wherein the guide member is divided into a plurality of parts in the sheet conveying direction. The shift device according to any one of claims 1 to 4,
Torque detection means for detecting torque of the first shift conveying member pair or the second shift conveying member pair,
A shift device, wherein a speed difference between the first pair of shift conveying members and the second pair of shift conveying members is changed based on the torque detection result of the torque detecting means. In the shift device according to claim 5,
A shift device, wherein the speed difference between the first pair of shift conveying members and the second pair of shift conveying members is changed so that the detected value of the torque detecting means maintains a predetermined value. A sheet conveying device comprising a shift means for shifting a conveyed sheet in a width direction perpendicular to the sheet conveying direction,
A sheet conveying apparatus comprising the shifting device according to any one of claims 1 to 6 as the shifting means. a sheet conveying means for conveying a sheet;
and an image forming device for forming an image on the sheet conveyed by the sheet conveying device,
An image forming apparatus comprising the sheet conveying device according to claim 7 as the sheet conveying means.

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