JP2007001694A - Sheet reversing device and image forming device equipped with sheet reversing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet reversing device and an image forming device equipped therewith capable of enhancing the handling speed of sheets while increase in the manufacturing cost is precluded and also the size is made compact by adopting an abutting/separating mechanism in a simple configuration to enable switching-back upon overlapping the front and rear edges of sheets of paper. <P>SOLUTION: The sheet reversing device is structured so that an reversing roller 41a and a follower roller 41b are installed on a switch-back passage 37 in such an arrangement that the follower roller 41b can abut to and separate from the reversing roller 41a, in which a driving force is transmitted to the two rollers 41a and 41b so as to rotate the two rollers 41a and 41b in the same direction, regular and reverse, and between the follower roller 41b and a drive shaft 41c, a one-way clutch 48 is installed to transmit the driving force to the follower roller 41b in the direction of drawing out a recording sheet of paper from the switch-back passage 37. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sheet reversing apparatus capable of reversing and transporting the front and back surfaces of a sheet, and an image forming apparatus such as a copying machine, a facsimile apparatus, and a printer apparatus incorporating the sheet reversing apparatus.

  In general, after an image is formed on one side of a sheet to be conveyed one by one, an image is formed on both sides of the sheet by forming an image on the other side by switching back and reversing in a switchback path. An image forming apparatus such as a copying machine or a printer that can be used has been put into practical use (for example, see Patent Documents 1 to 4).

A conventional image forming apparatus having this type of sheet reversing device will be described with reference to FIG. In FIG. 10, the description will be made using the paper reversing device of Patent Document 1.
In FIG. 10, a fixing device 9 provided in the image forming apparatus 1 includes a heat roller 9a and a pressure roller 9b that are pressed against each other, and fixes a toner image transferred to a sheet. .

  A drawing path 13 a is provided in the middle of the conveyance path 12 that connects the fixing device 9 and the discharge port 11 of the image forming apparatus 1, and the drawing path 13 a is conveyed downstream in the sheet conveyance direction with respect to the fixing apparatus 9. A branch from the road 12 is provided.

  A gate 10 is provided in the transport path 12, and the gate 10 is switched to a switching position where the sheet fed from the fixing device 9 is pulled into the pull-in path 13 a by switching the direction of the transported sheet.

  Further, a reverse paper discharge path 13b is branched from the middle of the pull-in path 13a, and this reverse paper discharge path 13b is provided with its end joined to the transport path 12 upstream of the discharge port 11 of the image forming apparatus 1. .

  A conveyance roller pair 15 is provided in the front stage of the gate 10, and a discharge roller pair 16 is provided in the rear stage of the gate 10. A driving roller pair 17 is provided on the drawing path 13a and the reverse conveying path 13b, and a reverse roller pair 18 capable of switching between normal rotation and reverse rotation is provided on the drawing path 13a.

The reverse roller pair 18 includes a movable roller 18a and a fixed roller 18b. The reverse roller pair 18 includes a roller holding member 19 that holds the reverse roller pair 18, and a spring that applies a nip load to the reverse roller pair 18. 20. A solenoid 21 for separating the movable roller 18a from the fixed roller 18b is provided.
When the movable roller 18 a is separated from the fixed roller 18 b, the roller holding member 19 is pulled up so that the solenoid 21 separates the movable roller 18 a of the reversing roller pair 18 against the tension of the spring 20, and the reversing roller pair 18. The structure which isolate | separates is known.

  FIG. 11 shows another example of the contact / separation mechanism. This abutment / separation mechanism includes an eccentric cam 22 having a motor 23 as a drive source, and the rotation of the eccentric cam 22 separates the reversing roller pair 18 against the tension of the spring 20.

  In the sheet reversing device having such a configuration, the gate 10 is switched to a position where the drawing path 13a and the conveying path 12 are communicated, and the sheet on which an image is formed on one side is drawn from the conveying path 12 to the drawing path 13a. Thereafter, the paper is nipped and conveyed by the reverse roller pair 18, the gate 10 is switched to a position where the draw path 13a and the reverse discharge path 13b are communicated, and the reverse roller pair 18 is driven in reverse to reverse the sheet from the draw path 13a. To the transport path 12. Further, in order to reduce the paper conveyance load, the reverse roller pair 18 is separated when the paper is carried out.

  By the way, in such a sheet reversing device, in order to increase the sheet conveyance speed and shorten the image forming time, the next end of the preceding sheet is not completely removed from the drawing path 13a. Since the paper cannot be switched back, the processing speed is greatly reduced.

In order to solve such a problem, the reverse roller pair 18 is separated when the trailing edge of the preceding paper and the leading edge of the succeeding paper are in the drawing path 13a and the front and rear edges of the paper overlap. Further, the conveyance load of the reverse roller pair 18 is prevented from being applied to the sheet, and the sheet is conveyed so as not to take a distance between the sheets, thereby improving the processing speed.
JP 2001-335215 A JP-A-5-35023 JP 2004-107073 A Japanese Patent No. 3285964

  However, in such a conventional paper reversing device, in order to allow overlap of the front and rear ends of the paper, in a direction against the tension of the spring 20 for nipping the movable roller 18a of the reversing roller pair 18. Since it is necessary to rotate the roller holding member 19, a driving force larger than the tension of the spring 20 is required, resulting in a problem that the solenoid 21 or the motor 23 is enlarged.

  In addition, since the separated movable roller 18a is stopped, there is a possibility of a paper transport load. Therefore, the movable roller 18a needs to be largely separated from the fixed roller 18b. Must be bigger. For this reason, a large solenoid or the like is required, which increases the manufacturing cost of the sheet reversing device and increases the size.

  The present invention has been made to solve the conventional problems, and employs a simple configuration contact / separation mechanism so that the front and rear ends of a plurality of sheets can be overlapped and switched back. An object of the present invention is to provide a sheet reversing apparatus and an image forming apparatus including the sheet reversing apparatus that can increase the processing speed of the sheet while preventing an increase in cost and downsizing.

  The sheet reversing device of the present invention includes a reversing path for reversing a sheet conveyed from a processing position, a switchback path for conveying a sheet reversed through the reversing path, and a sheet carried out from the switchback path. At least two pairs are provided in the switchback path and the re-feed path for re-feeding toward the processing position so that the sheet is transported in the direction of drawing in the switchback path and in the direction of pulling out from the switchback path. A first roller capable of rotating forward and backward, a second roller slidably contacting the first roller, and a contact / separation means for contacting / separating at least one of the second rollers to / from the first roller. In the sheet reversing device, a driving force is applied to the first roller and the second roller so as to rotate the first roller and the second roller forward and backward in the same direction. A one-way which is interposed between the driving means for transmitting and the second roller and the driving shaft of the second roller and transmits the driving force from the driving means to the second roller in a direction to pull out the paper from the switchback path. It is comprised from what provided the clutch.

With this configuration, the driving force is transmitted to the first roller and the second roller so that the first roller and the second roller rotate forward and backward in the same direction, and the sheet is interposed between the driving shafts of the second roller and the second roller. Since the one-way clutch that transmits the driving force to the second roller in the direction of pulling out the sheet from the switchback path is provided, the first roller and the second roller are in sliding contact with each other to rotate the sheet in the direction of pulling out the sheet from the switchback path. The roller and the second roller rotate in opposite directions.
At this time, since the second roller rotates with the first roller without being transmitted from the drive shaft by the one-way clutch, the sheet is sandwiched between the first roller and the second roller by the driving force of the first roller, and the switch It is transported from the back path to the re-transport path.

Further, when the sheet is drawn into the switchback path, the second roller is separated from the first roller, and the first roller and the second roller are rotated in the same direction.
At this time, since the second roller is locked by the one-way clutch and the driving force is transmitted from the drive shaft to rotate in the paper drawing direction, the paper drawn out from the switchback path to the re-conveyance path remains and the preceding paper When the trailing edge of the trailing edge and the trailing edge of the preceding paper overlap on the switchback path, the first roller and the second roller do not apply a transport load to the front and rear edges of the paper.

  For this reason, the separation distance between the first roller and the second roller need only be at least equivalent to the thickness of two sheets, and the driving force of the contact / separation means can be reduced. Accordingly, it is possible to prevent the manufacturing cost of the contact / separation means from increasing, and to increase the paper processing speed while reducing the size.

  Further, since the driving force of the abutting / separating means can be reduced, when the paper jam occurs on the switchback path, the second roller is moved from the first roller with a small force even when the power is turned off. It can be contacted and separated, and jam processing can be easily performed.

The sheet reversing device of the present invention is configured by providing the second roller on the re-conveyance path side.
With this configuration, when the sheet is drawn into the switchback path, the second roller is separated from the first roller, and the first roller and the second roller are rotated in the same direction.

At this time, since the second roller is locked to the one-way clutch and the driving force is transmitted from the drive shaft to rotate in the paper drawing direction, the paper drawn out from the switchback path to the re-conveyance path remains, and the preceding paper When the trailing edge of the preceding sheet and the trailing edge of the preceding sheet overlap on the switchback path, the second roller that separates rotates in the direction of pulling out the sheet, so that the preceding sheet pulled out from the switchback path is moved by the second roller. Conveyance is urged in the pull-out direction.
Further, since the first roller rotates in the direction in which the paper is drawn, the subsequent paper drawn into the switchback path is urged to be conveyed in the pull-in direction by the first roller.

In the sheet reversing device of the present invention, at least the surface of the second roller is constituted by a low friction member.
With this configuration, when the second roller is separated from the first roller, it is possible to further prevent the conveyance load from being applied to the front and rear ends of the overlapping sheets.

  The contact / separation means of the sheet reversing device of the present invention is provided between the second roller and another first roller adjacent to the first roller that is in sliding contact with the second roller. An arm member that contacts and separates the second roller from the first roller as one roller rotates, and a torque limiter interposed between the other first roller and the arm member. It is composed of what it has.

  With this configuration, by utilizing the rotation of the other first roller, the second roller can be contacted / separated, so that it is not necessary to use a solenoid or the like for the contact / separation means, The configuration of the abutting / separating means can be further simplified.

  In addition, since a torque limiter is interposed between the other first roller and the arm member, the load for contacting and separating the second roller with respect to the first roller can be reduced. The impact sound when the second roller is pressed can be reduced, and the noise can be reduced.

  Further, the contact / separation means of the sheet reversing device of the present invention is provided on the first roller and a pressure member that presses the second roller against the first roller, and the first roller rotates when the first roller rotates. A cam member that separates the second roller from the first roller against the pressure applied by the pressure member, and a torque limiter interposed between the first roller and the cam member. Has been.

  With this configuration, the second roller can be contacted / separated by utilizing the rotation of the first roller, so that it is not necessary to use a solenoid or the like for the contact / separation means. -The structure of the separation means can be further simplified.

  In addition, since a torque limiter is interposed between the first roller and the cam member to reduce the load for contacting and separating the second roller from the first roller, the first roller and the second roller It is possible to reduce the impact sound when the roller is pressed and to reduce the noise.

Further, the sheet reversing device of the present invention comprises a rotating fulcrum of the cam member installed at the rotation center of the first roller.
With this configuration, the cam member can be rotated with a small force, and an increase in the driving force of the first roller can be prevented.

The image forming apparatus according to the present invention includes an image forming unit that is provided at the processing position and forms an image on a sheet, and the sheet reversing apparatus described above.
With this configuration, it is possible to prevent an increase in the manufacturing cost of the sheet reversing device, to reduce the size, and to increase the processing speed of the image forming operation.

Further, the image forming apparatus of the present invention is constituted by the image forming apparatus comprising a copying machine.
With this configuration, it is possible to prevent an increase in the manufacturing cost of the sheet reversing device, to reduce the size, and to increase the processing speed of the image forming operation.

In the image forming apparatus of the present invention, the image forming apparatus comprises a facsimile machine.
With this configuration, it is possible to prevent an increase in the manufacturing cost of the sheet reversing device, to reduce the size, and to increase the processing speed of the image forming operation.

In the image forming apparatus of the present invention, the image forming apparatus comprises a printer device.
With this configuration, it is possible to prevent an increase in the manufacturing cost of the sheet reversing device, to reduce the size, and to increase the processing speed of the image forming operation.

  The present invention employs a contact / separation mechanism having a simple configuration so that the front and rear ends of a plurality of sheets can be overlapped and switched back, thereby preventing an increase in manufacturing cost and miniaturization. On the other hand, it is possible to provide a sheet reversing apparatus capable of increasing the sheet processing speed and an image forming apparatus including the sheet reversing apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIGS. 1 to 7 are views showing a first embodiment of a sheet inverting device and an image forming apparatus provided with the sheet inverting device according to the present invention, and show an example in which the image forming apparatus is applied to a printer apparatus. .

  First, the configuration will be described. FIG. 1 is a schematic diagram showing a conveyance path of the printer apparatus. In FIG. 1, paper cassettes 22a and 22b for storing two levels of recording paper (paper) are provided below the printer device 21, and the recording paper stored in the paper cassettes 22a and 22b is separated and fed. A sheet is fed one by one by the roller 23.

  The recording sheet fed by the separation feeding roller 23 is nipped and conveyed by the grip roller pair 24, and then passes through an intermediate roller pair 25 provided at a junction point with a re-conveying path described later, and a registration roller pair 26. It is conveyed to.

The separation feeding roller 23, the grip roller pair 24, the intermediate roller pair 25, and the registration roller pair 26 are independently driven by a clutch and a stepping motor, not shown.
A photosensitive drum 27 as an image carrier is provided above the registration roller pair 26, and a known electrophotographic process is performed on the photosensitive drum 27 by a charging device, a developing device, a transfer device, etc. (not shown). Thus, a toner image is formed. The position where the photosensitive drum 27 is provided is a processing position, and the photosensitive drum 27 and a charging device, a developing device, a transfer device, etc. (not shown) constitute an image forming unit.

  The fed recording paper is conveyed to the transfer position of the photosensitive drum 27 in synchronization with the toner image formed on the photosensitive drum 27 by the registration roller pair 26, so that the recording paper on the photosensitive drum 27 is transferred. The toner image is transferred. The recording sheet on which the transfer has been completed is conveyed to the fixing device 29 by the intermediate belt 28.

  The fixing device 29 includes a pressure roller 29a and a heating roller 29b, and fixes the toner image transferred onto the recording paper to the recording paper. Then, the recording sheet after fixing is nipped between the conveyance belt 30 and the conveyance roller 31 and conveyed.

  A branching claw 32 is provided on the downstream side of the conveying belt 30. When the recording paper is not reversed, the branching claw 32 is switched to a position where the discharge roller pair 33 and the conveying belt 30 are communicated. The paper is discharged out of the printer device 21 by the paper discharge roller pair 33.

  The branch claw 32 is switched to a position where the conveyance belt 30 and the reversing device 34 as a paper reversing device communicate with each other when the reverse ejection or double-sided copying of the recording paper is selected. To 34.

  As shown in FIG. 2, the reversing device 10 includes a reversing path 35, a reversing forward path 36a, a reversing forward path 36b, a switchback path 37, a re-conveying path 38, and various rollers and branch claws, which will be described later. ing.

  The reversing path 35 is provided with conveying roller pairs 39a, 39b, 39c, and the recording paper conveyed to the reversing path 35 is sandwiched between the conveying roller pairs 39a, 39b and forms a reversing path together with the reversing path 35. It is conveyed to 36a.

An inlet roller pair 40 is provided in the reverse forward path 36 a, and the recording paper conveyed to the reverse forward path 36 a is nipped by the inlet roller pair 40 and conveyed to the switchback path 37. The switchback passage 37 is provided with a pair of reversing rollers 41 and 42. As will be described later, the driven roller 41b of the pair of reversing rollers 41 abuts / separates from the reversing roller 41a by abutment / separation means. Yes. In the present embodiment, driven rollers 41b and 42b are provided on the re-conveyance passage 38 side.
An entrance sensor 43 is provided in the reverse path 36a upstream of the entrance roller pair 40. When the entrance sensor 43 detects the leading edge of the recording paper, the reverse roller pair 41, 42 is switched back using the detection as a trigger. The recording paper is rotated so as to be drawn into the passage 37, and the driving is stopped when the trailing edge of the recording paper reaches a predetermined stop position.

  Thereafter, the pair of reversing rollers 41 and 42 are driven in the reverse direction in the direction in which the recording paper is pulled out from the switchback passage 37, and the recording paper is pulled out from the switchback passage 37 with the rear end of the recording paper being the front end.

  An exit roller pair 44 is provided at the entrance of the re-conveying passage 38 and a switching claw 45 is provided in the reverse forward passage 36b. The recording paper drawn from the switchback passage 37 is sandwiched between the exit roller pair 44. Are transported. At this time, the driven roller 41 b is separated from the reverse roller 41 a, so that the subsequent recording paper can be conveyed to the switchback path 37.

  The switching claw 45 is adapted to switch the conveyance direction depending on whether the recording sheet is reversed and discharged or when duplex recording is performed. When the recording sheet is re-conveyed to the photosensitive drum 27, the switchback passage 37 is provided. The re-conveying passage 38 is switched to a position where it is communicated, and the recording sheet to be switched back is reversed and conveyed to the re-conveying passage 38 by the reversing roller pairs 41 and 42 and the exit roller pair 44.

  A plurality of conveying roller pairs 46 are provided in the reconveying path 38, and the recording paper conveyed to the reconveying path 38 is nipped by the conveying roller pair 46 and conveyed toward the intermediate roller 25. The switching claw 45 can be switched to a position where the switchback path 37 and the reverse return path 36b are communicated when the recording paper is discharged, and conveys the switched back recording paper to the reverse return path 36b.

  The recording paper conveyed to the reverse return path 36b is nipped and conveyed by the exit roller pair 44, and is nipped and conveyed by the conveyance roller pair 47 and the conveyance roller pairs 39a and 39c provided in the reverse path 35, and then discharged. The paper is sandwiched between the roller pair 33 and discharged outside the printer device 21.

3 to 5 are configuration diagrams of the reversing roller pair 41 and 42.
FIG. 3 is a view showing the reverse roller pair 41. In FIG. 3, the surface of the driven roller 41b is formed of a low friction member such as plastic, and a one-way clutch 48 is interposed between the drive shaft 41c of the driven roller 41b and the driven roller 41b. In this embodiment, the reversing roller pair 41 and 42 are rotated forward and backward in the same direction by driving means described later, and the one-way clutch 48 is recorded from the switchback passage 37 as shown in FIG. A driving force is transmitted from the driving means to the driven roller 41b in the direction of pulling out the paper. That is, the driven roller 41b is rotated by itself when the driving force is transmitted in the counterclockwise direction.
In this embodiment, the reversing rollers 41a and 42a constitute a first roller, and the driven rollers 41b and 42b constitute a second roller.

  As shown in FIGS. 4 and 5, one end of a rotating arm (arm member) 50 is attached to the drive shaft 42 d of the reverse roller 42 a adjacent to the reverse roller 41 via a torque limiter 49. The rotation fulcrum of the rotation arm 50 is installed at the rotation center of the reversing roller 42a, that is, the center axis of the drive shaft 42d.

  A notch 50a is formed at the other end of the rotating arm 50, and a drive shaft 41c is inserted into the notch. Further, a spring (pressure member) 51 is provided in the notch 50a. The spring 51 urges (presses) the driven roller 41b against the reverse roller 41a so that the driven roller 41b and the reverse roller 41a are pressed. It is in sliding contact.

  A stopper member 52 fixed to the main body side of the printer device 21 is provided below the driven roller 41b. The stopper member 52 regulates the rotation position of the rotation arm 50 to separate the driven roller 41b. The distance is specified.

  Further, a belt member 53 is interposed between the drive shaft 41c of the driven roller 41b and the drive shaft 42d of the reverse roller 42a. The belt member 53 is driven by a motor (not shown), and the driven roller 41b and the reverse roller 42a are the same. It is designed to rotate in the direction.

  Further, a belt member (not shown) is also interposed in the drive shaft 42c of the driven roller 42b and the drive shaft 41d of the reverse roller 41a. This belt member is also driven by a motor (not shown), and the driven roller 42b and the reverse roller 41a are the same. It is designed to rotate in the direction.

  Further, the rotation direction of the reverse roller 41a and the driven roller 41b is set to be the same by the belt member 53 and the like. In the present embodiment, the belt member 53 and the like constitute the driving means, and the rotating arm 50, the spring 51, and the stopper member 52 constitute the contact / separation means. In addition, although the rotation center of the rotation arm 50 and the rotation center of the reversing roller 42a are coaxial, it may be configured as another center using a gear, a belt, or the like.

  In the contact / separation means having such a configuration, when the reversing roller 42a is rotated in the clockwise direction, the rotating arm 50 is rotated in the clockwise direction to add the driven roller 41b to the reversing roller 41a. Pressure (see FIG. 4).

  When the reversing roller 42a is rotated in the clockwise direction to exceed the torque limit of the torque limiter 49, the reversing roller 42a is idled with respect to the rotating arm 50, and the rotation of the reversing roller 42a is hindered. The reversing roller 42a rotates smoothly.

When the reversing roller 42a is rotated in the counterclockwise direction, the rotating arm 50 is rotated in the counterclockwise direction so that the rotating arm 50 is rotated to a position where the rotating arm 50 contacts the stopper member 52, and the driven roller 41b is rotated. Separated from the reversing roller 41a (see FIG. 5).
Further, when the rotating arm 50 comes into contact with the stopper member 52, it is possible to prevent the spring 51 from being bent and absorb the impact, thereby generating noise and preventing the driven roller 41b from being damaged. Further, when the reverse roller 42a is rotated counterclockwise and the torque limiter 49 exceeds the torque limit, the reverse roller 42a idles with respect to the rotating arm 50, and the rotation of the reverse roller 42a is obstructed. The reversing roller 42a rotates smoothly.

Next, the reverse conveyance operation of the recording paper will be described with reference to FIGS.
When the first recording sheet is conveyed toward the switchback path 37 via the reverse forward path 36a, when the inlet sensor 43 detects the leading edge of the recording sheet, the detection is used as a trigger from the motor via the belt member 53 and the like. Since the driving force is transmitted to the pair of reverse rollers 41 and 42, as shown in FIG. 2, the reverse rollers 41a and 42a rotate counterclockwise and the driven rollers 41b and 42b rotate clockwise.

  At this time, since the reversing roller 42a rotates in the counterclockwise direction, the rotating arm 50 rotates in the counterclockwise direction and rotates to a position where the rotating arm 50 contacts the stopper member 52 as shown in FIG. The driven roller 41b moves away from the reverse roller 41a as shown by the broken line in FIG. 2, but the recording paper (the recording paper to be selected is indicated by P1) is placed on either the inlet roller pair 40 or the reverse roller pair 42. Since the paper is pinched, the recording paper is surely drawn into the switchback passage 37.

  Next, when the recording paper is drawn to a predetermined position in the switchback passage 37, the motor is driven in reverse, so that the reverse rollers 41a and 42a are rotated in the clockwise direction via the belt member 53 and the like as shown in FIG. As the roller rotates, the driven rollers 41b and 42b rotate counterclockwise.

  At this time, the rotating arm 50 rotates clockwise and presses the driven roller 41b against the reverse roller 41a. Here, in this embodiment, since the reverse roller 41a and the driven roller 41b rotate in the same direction, when the recording paper is pulled out from the switchback path 37, the driven roller 41b moves the recording paper to the switchback path. It rotates in the clockwise direction to be pulled into 37.

  However, since the driving force is transmitted to the driven roller 41b in the direction of pulling out the recording paper from the switchback passage 37, the driven roller 41b rotates with the reverse roller 41a and rotates counterclockwise to remove the recording paper. Pull out from the switchback passage 37.

  When the trailing edge of the preceding recording sheet comes out of the reverse roller pair 42 and the leading edge of the succeeding recording sheet (the succeeding recording sheet is indicated by P2) is detected by the entrance sensor 43, the detection is shown in FIG. As described above, since the driving force is transmitted from the motor to the pair of reverse rollers 41 and 42 via the belt member 53 and the like, the reverse rollers 41a and 42a rotate counterclockwise and the driven rollers 41b and 42b rotate clockwise. Rotate in the direction.

  At this time, since the reverse roller 42a rotates again in the counterclockwise direction, the rotating arm 50 rotates in the counterclockwise direction as shown in FIG. 5 until the rotating arm 50 contacts the stopper member 52. By rotating, the driven roller 41b is separated from the reversing roller 41a. At this time, since the trailing edge of the preceding recording sheet and the leading edge of the succeeding recording sheet pass each other, they temporarily overlap.

  At this time, the reversing roller 41a rotates in the clockwise direction for drawing the recording paper into the switchback passage 37, and the driven roller 41b rotates in the counterclockwise rotation direction for drawing out the recording paper from the switchback passage 37. FIG. As shown, the driven roller 41b continues to rotate in the counterclockwise direction while being separated from the reverse roller 41a because the one-way clutch 48 is locked.

  As a result, the succeeding recording sheet can be drawn into the switchback passage 37 without leaving an interval between the preceding recording sheet and the succeeding recording sheet, and the processing speed of the recording sheet can be improved.

  As described above, in the present embodiment, the reverse roller 41a and the driven roller 41b are provided in the switchback passage 37, and the driven roller 41b is configured to be freely contacted and separated from the reverse roller 41a, and the reverse roller provided in the driven roller 41b. Driving force is transmitted to the reversing roller 41a and the driven roller 41b so that the roller 41a and the driven roller 41b rotate forward and backward in the same direction, and the recording paper is pulled out from the switchback passage 37 between the driven roller 41b and the driving shaft 41c. Since the one-way clutch 48 for transmitting the driving force to the driven roller 41b in the direction is provided, the driven roller 41b is moved to the one-way when the recording paper is conveyed on the switchback passage 37 in a state where the driven roller 41b is separated from the reverse roller 41a. The drive force is transmitted from the drive shaft 41c by locking with the clutch 48, Since the recording paper drawn out from the switchback passage 37 to the re-conveyance passage 38 remains, the trailing edge of the preceding paper and the trailing edge of the preceding paper are on the switchback passage 37. Can be prevented from being applied to the front and rear ends of the recording paper by the reverse roller 41a and the driven roller 41b.

  Therefore, the separation distance between the reversing roller 41a and the driven roller 41b need only be at least equivalent to the thickness of two recording sheets, and the driving force of the contact / separation means can be reduced. Therefore, it is possible to increase the processing speed of the recording paper while preventing the manufacturing cost of the contact / separation means from increasing and reducing the size.

  Further, since the driving force of the abutting / separating means can be reduced, when the recording paper jam occurs on the switchback path 37, the driven roller 41b is made smaller than the reversing roller 41a even when the power is turned off. It can be contacted / separated by force, and jamming can be easily performed.

  In this embodiment, since the driven roller 41b is provided on the re-conveying path 38 side, when the recording paper is drawn into the switchback path 37, the driven roller 41b is separated from the reversing roller 41a, and the reversing roller 41a and the driven roller are separated. When the rollers 41b are rotated in the same direction, the driven roller 41b is locked by the one-way clutch 48 and rotates in the recording paper drawing direction, so that the recording paper drawn out from the switchback passage 37 to the re-conveyance passage 38 remains. Thus, when the trailing edge of the preceding recording sheet and the trailing edge of the preceding recording sheet overlap on the switchback path 37, the driven roller 41b that separates rotates in the direction of pulling out the recording sheet. The preceding recording paper drawn out from the paper is conveyed by the driven roller 41b in the pulling direction. It can prompt.

  Further, since the reversing roller 41a rotates in the direction in which the recording paper is drawn, the conveying direction of the succeeding recording paper drawn into the switchback passage 37 can be urged by the reversing roller 41a in the drawing direction.

  In this embodiment, since the surface of the driven roller is composed of a low friction member, when the driven roller 41b is separated from the reversing roller 41a, the conveyance load is further prevented from being applied to the front and rear ends of the overlapping recording sheets. can do. The driven roller 41b may be entirely composed of a low friction member such as plastic.

  In this embodiment, the contact / separation means is provided between the driven roller 41b and the reverse roller 42a adjacent to the reverse roller 41a, and the driven roller 41b is reversed as the reverse roller 42a rotates. Since the rotation arm 50 is brought into contact with and separated from the roller 41a, and the torque limiter 49 is interposed between the reversing roller 42a and the rotation arm 50, the rotation of the reversing roller 42a is used. The driven roller 41b can be brought into contact with or separated from the reversing roller 41a. For this reason, it is unnecessary to use a solenoid or the like for the contact / separation means, and the configuration of the contact / separation means can be further simplified.

  In addition, since a torque limiter 49 is interposed between the reversing roller 41a and the rotating arm 50, the load for contacting and separating the driven roller 41b with respect to the reversing roller 41a can be reduced. Can be reduced in impact noise when pressed against the reversing roller 41a, and noise can be reduced.

  In the present embodiment, the reversing device 34 is provided in the printer device 21 and the processing speed of the recording paper can be increased. Therefore, the processing speed of the image forming operation can be increased. In this embodiment, the image forming apparatus is applied to a printer. However, the present invention is not limited to this, and the present invention may be applied to a facsimile machine, a copying machine, and a multifunction machine in which a copying function and a facsimile function are combined. In addition to the image forming apparatus, the image forming apparatus may be provided in an image reading apparatus such as a scanner.

  FIG. 8 and FIG. 9 are views showing a second embodiment of the sheet reversing device and the image forming apparatus provided with the sheet reversing device according to the present invention. Since the first embodiment is different from the first embodiment and the other configurations are the same as those of the first embodiment, detailed description thereof is omitted.

  8 and 9, a cam member 62 is attached to the drive shaft 41d of the reversing roller 41a via a torque limiter 61. The rotation fulcrum of the cam member 62 is the rotation center of the reversing roller 41a, that is, It is installed on the central axis of the drive shaft 41d. The cam member 62 is formed with a notch 62 a, and the notch 62 a is provided with a stopper material 63 fixed to the main body side of the printer device 21.

  The driven roller 41 b is inserted into the notch 64 a of the pressure bracket 64, and the pressure bracket 64 is fixed to the main body side of the printer device 21. The notch 64a is provided with a spring 65 as a pressure member, and this spring 65 biases (presses) the driven roller 41b against the reverse roller 41a.

  The drive force of the motor 67 is transmitted to the drive shaft 41c of the driven roller 41b via the belt member 66. Although not shown, the drive shaft 41d of the reverse roller 41a is also connected to the drive shaft 41c via the belt member. Thus, the driving force of the motor 67 is transmitted. In this case, a belt member 66 or the like for driving the reverse roller 41a and the driven roller 41b may be provided adjacent to the output shaft of the motor 67. Therefore, in this embodiment, the reverse roller 41a and the driven roller 41b rotate in the same direction. The belt member 66 and the motor 67 constitute drive means.

  In the contact / separation means having such a configuration, when the reversing roller 42a is rotated in the clockwise direction, the cam member 62 is rotated in the clockwise direction to be separated from the drive shaft 41c of the driven roller 41b. Therefore, the driven roller 41b contacts the reversing roller 41a by the urging force of the spring 65 (see FIG. 8).

  At this time, the notch 62 a abuts against the stopper member 63 and restricts the rotation of the cam member 62, and at the same time exceeds the torque limit of the torque limiter 61, so that the reversing roller 42 a rotates idly with respect to the cam member 62. Thus, the rotation of the reverse roller 42a is prevented from being hindered, and the reverse roller 42a rotates smoothly.

When the reverse roller 42a is rotated in the counterclockwise direction, the cam member 62 rotates in the counterclockwise direction and the cam member 62 presses the drive shaft 41c of the driven roller 41b. At this time, since the drive shaft 41c descends along the notch 64a against the urging force of the spring 65, the driven roller 41b is separated from the reverse roller 41a (see FIG. 9).
When the notch 62a of the cam member 62 comes into contact with the stopper member 63, the rotation of the cam member 62 stops and the driven roller 41b is separated from the reversing roller 41a by a certain distance to maintain the state.
Further, when the cam member 62 comes into contact with the drive shaft 41c, it is possible to prevent the spring 65 from being bent and absorb the impact, thereby generating noise and preventing the driven roller 41b from being damaged. Further, when the notch 62a abuts against the stopper material 63, the torque limit of the torque limiter 61 is exceeded, so that the reversing roller 42a idles with respect to the cam member 62, thereby hindering the rotation of the reversing roller 42a. The reversing roller 42a rotates smoothly.

  Even if the abutting / separating means is configured in this way, the same effect as that of the first embodiment can be obtained. Further, in this embodiment, since the rotation fulcrum of the cam member 62 is set at the rotation center of the reverse roller 41a, the cam member 62 can be rotated with a small force, and the driving force of the reverse roller 41a is increased. Can be prevented. In addition, although the rotation center of the cam member 62 and the rotation center of the reversing roller 42a are coaxial, you may comprise in another center using a gear, a belt, etc.

  As described above, the sheet reversing device and the sheet forming apparatus including the sheet reversing device according to the present invention adopt a simple configuration contact / separation mechanism to overlap the front and rear ends of a plurality of sheets and switch back. In this way, the manufacturing cost can be prevented from increasing, the size can be reduced, and the paper processing speed can be increased. Therefore, it is useful as an image forming apparatus such as a copying machine, a facsimile machine, and a printer apparatus in which the paper inverting apparatus is incorporated.

1 is a schematic configuration diagram of a sheet reversing device and an image forming apparatus including a sheet reversing device according to a first embodiment of the present invention. 1 is a schematic configuration diagram of a sheet reversing device according to a first embodiment and a diagram illustrating a conveyance state of a recording sheet (A) is a figure which shows transmission of the driving force when the reverse roller and driven roller which contact | connect a 1st Embodiment, (b) is transmission of the driving force when a driven roller separates from a reverse roller. The figure which shows, (c) is a figure which shows the locking direction of a driven roller It is a figure which shows the contact and separation means of the paper reversing device concerning a 1st embodiment, and is a figure showing the state where a reversing roller and a follower roller contacted It is a figure which shows the contact / separation means of the paper reversing apparatus which concerns on 1st Embodiment, and is a figure which shows the state which the driven roller separated from the reversing roller 1 is a schematic configuration diagram of a sheet inverting device of a sheet inverting device according to a first embodiment and a diagram illustrating a recording paper conveyance state; 1 is a schematic configuration diagram of a sheet inverting device of a sheet inverting device according to a first embodiment and a diagram illustrating a recording paper conveyance state; FIG. 6 is a diagram illustrating a contact / separation unit provided in a sheet reversing device and an image forming apparatus including a sheet reversing device according to a second embodiment of the present invention, in a state in which a reversing roller and a driven roller are in contact with each other. Illustration It is a figure which shows the contact / separation means which concerns on 2nd Embodiment, and is a figure which shows the state which the driven roller separated from the reverse roller Figure showing a conventional paper reversing device Figure showing a conventional paper reversing device

Explanation of symbols

21 Printer device (image forming device)
27 Photosensitive drum (image forming means, processing position)
35 Reverse path 36a Reverse path (Reverse path)
37 Switchback passage 38 Re-transport passage 41a, 42a Reverse roller (first roller)
41b, 42b driven roller (second roller)
48 One-way clutch 49, 61 Torque limiter 50 Rotating arm (arm member)
51, 65 Spring (Pressurizing member)
53, 66 Belt member (drive means)
62 Cam member 67 Motor (drive means)

Claims (10)

A reversing path for reversing the sheet conveyed from the processing position, a switchback path for conveying the sheet reversed through the reversing path, and a sheet unloaded from the switchback path for reversing to the processing position A re-conveying passage for re-conveying toward the first and at least two pairs of the switch-back passages, and a first reversible rotation so as to convey the paper in a direction in which the paper is drawn into the switch-back passage and a direction in which the paper is drawn out from the switch-back passage. A sheet reversing apparatus comprising: a roller and a second roller that is in sliding contact with the first roller; and a contact / separation unit that contacts / separates at least one of the second rollers with the first roller;
Driving means for transmitting a driving force to the first roller and the second roller so as to rotate the first roller and the second roller forward and backward in the same direction; and driving shafts of the second roller and the second roller And a one-way clutch for transmitting a driving force from the driving means to the second roller in a direction to pull out the paper from the switchback path. The sheet reversing device according to claim 1, wherein the second roller is provided on the re-conveyance path side. The sheet reversing device according to claim 1, wherein at least a surface of the second roller is formed of a low friction member. The contact / separation means is provided between the second roller and another first roller adjacent to the first roller that is in sliding contact with the second roller, and as the other first roller rotates, The arm member which makes a 2nd roller contact | abut / separate with respect to the said 1st roller, and the torque limiter interposed between the said other 1st roller and the said arm member, It is characterized by the above-mentioned. The sheet reversing device according to any one of claims 1 to 3. The contact / separation means is provided on the first roller for pressing the second roller against the first roller, and resists the pressure applied by the pressure member when the first roller rotates. 4. A cam member for separating the second roller from the first roller, and a torque limiter interposed between the first roller and the cam member. The sheet reversing device according to any one of the above. The sheet reversing device according to claim 5, wherein a rotation fulcrum of the cam member is installed at a rotation center of the first roller. An image forming apparatus comprising: an image forming unit that is provided at the processing position and forms an image on a sheet; and the sheet reversing device according to claim 1. 8. The image forming apparatus according to claim 7, wherein the image forming apparatus comprises a copying machine. 8. The image forming apparatus according to claim 7, wherein the image forming apparatus is a facsimile machine. The image forming apparatus according to claim 7, comprising a printer device.

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