JP2005331863A - Switchback apparatus for image forming apparatus carrying out both sides printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a switchback apparatus for an image forming apparatus easily carrying out a jam processing. <P>SOLUTION: The switchback apparatus 7 for the image forming apparatus carrying out both sides printing is provided with a driving roller 711 which can be driven to be rotated in a forward or reverse direction; a following roller 712 to be removably brought into press-contact to the driving roller 711; an arm 73 to be freely rotatably supported by a shaft and supporting the following roller 712; an energizing spring 76 energizing the arm 73 in the pressing direction; a separating/contacting solenoid 75 the arm 73 against the energizing by the energizing spring in jam processing; and a knob 80 for jam processing fixed to a revolving shaft 74 of the arm 73. Gears 781 and 782 to be engaged with each other are installed on the rotating shaft 74 of the arm 73 and on a rotating shaft 72 of the following roller 712 and a torque limiter 79 is provided to increase the rotating torque of the gears 781 and 782 by the rotation of the nob 80 in jam processing. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a copying machine, a laser printer, a facsimile, and the like, and more particularly to a switchback device of an image forming apparatus using an electrophotographic technique.

  An example of a conventional image forming apparatus capable of duplex printing will be described with reference to FIGS. In FIG. 4, the sheets fed one by one from the sheet feeding cassette 1 by the sheet feeding roller 11 pass through the conveyance path 21, and the leading end is adjusted by the registration unit 3 and waits, and the sheet is fed to the image forming unit 4 at a predetermined timing. The toner image transported and formed by the image forming unit 4 is transferred to the first surface of the paper by the transfer unit 45. The sheet on which the unfixed toner image is transferred to the first surface is conveyed to the nip portion between the heat roller 51 and the pressure roller 52 of the fixing device 5 through the conveyance path 24, and the two rollers are nipped and heated. The unfixed toner image on the first side is fixed. Next, the sheet having the image on the first surface is transferred to the switchback device 7 via the upstream conveying path 25 by the branching unit 6, and the conveying direction is changed in the switchback device 7 to change the downstream conveying path 26. It is handed over to. Subsequently, the sheet having an image on the first surface passes through the downstream side conveyance path 26, the lower conveyance path 27, and the vertical conveyance path 28, and is re-adjusted at the registration unit 3 and waits, and forms the image at a predetermined timing. The toner image formed by the image forming unit 4 is transferred to the second surface of the sheet by the transfer unit 45. The sheet on which the unfixed toner image is transferred to the second surface is conveyed to the nip portion between the heat roller 51 and the pressure roller 52 of the fixing device 5 by the conveyance path 24, and the two rollers sandwich the sheet. The unfixed toner image on the second surface is fixed by heating. Thus far, the paper on which images are printed on both sides is discharged by the branching unit 6 to the paper discharge tray 9 via the paper discharge unit 29.

  As shown in FIG. 5, the switchback device 7 includes a reversing tray 70, a driving roller 711 provided on a lower side of a sheet conveying surface of the reversing tray 70, and a sheet of the reversing tray 70 with respect to the driving roller 711. A switchback roller pair 71 comprising a driven roller 712 that is detachably contacted on the upper side of the conveying surface, and switchback roller driving means (not shown) that rotationally drives the drive roller 711 in either the forward or reverse direction. An arm 73 rotatably provided to support the driven roller 712, an urging spring 76 that urges the arm 73 in a pressure-contact direction, and against the urging by the urging spring 76 during jam processing. A separation solenoid 75 for rotating the arm 73 is provided.

With this configuration, the paper P transported from the upstream transport path 25 enters the switchback device 7 by driving the pair of entrance rollers 251 and 252 and is transported to the switchback roller pair 71. At this time, when the sheet P is shifted in the width direction from the predetermined range or oblique conveyance occurs, the leading end of the sheet P abuts against the switchback roller pair 71 and bends, and the pair of entry rollers 251 and 252 and the switchback roller In a state where the sheet P is engaged with the pair 71, a sheet jam (jam) occurs between the upstream conveyance path 25 and the switchback device 7 (see FIG. 5).
JP 10-39563 A

  When such a jam occurs, the separation / separation solenoid 75 is actuated to rotate the jam, and the arm 73 is rotated so that the driven roller 711 is separated from the drive roller 712 (a broken line position in FIG. 5). The nip pressure of the switchback roller pair 71 is released.

  For this reason, by applying the technique described in Patent Document 1, a hand knob is attached to the rotating shaft 72 of the driven roller 712, and the driven roller 712 runs idle even when the knob is turned, and the nip pressure of the switchback roller pair 71 Cannot be obtained, and the paper P biting the entry roller pair 251 and 252 cannot be drawn into the switchback device 7. In addition, if the paper P bitten by the pair of entry rollers 251 and 252 is pulled by hand, the paper P is torn off, and a piece of paper remains in the upstream conveyance path P, thus requiring a troublesome removal work. .

  SUMMARY An advantage of some aspects of the invention is that it provides a switchback device for an image forming apparatus that can easily perform jam processing.

  In order to achieve the above object, a switchback device of an image forming apparatus capable of duplex printing according to the present invention includes a drive roller that is rotationally driven so as to be able to rotate forward and backward, a driven roller that is press-contacted so as to be detachable from the drive roller, An arm that is pivotally supported to support the driven roller, an urging unit that urges the arm in a pressure-contact direction, and the arm that rotates against the urging by the urging unit during jam processing. A jamming knob fixed to the rotation shaft of the arm, and a gear that meshes with the rotation shaft of the arm and the rotation shaft of the driven roller. Torque increasing means for increasing the rotational torque of the gear by the rotation of the knob is provided.

  Further, the torque increasing means comprises a torque limiter attached to a rotating shaft of the driven roller. The torque limiter is fitted between a rotation shaft of the driven roller and an inner periphery of a gear disposed on the driven roller.

  According to the present invention, since the rotational torque of the gear is increased by the torque increasing means, when the knob is rotated during the jam processing, a force is applied in the press-contact direction with respect to the gear disposed on the driven roller at the meshing portion between the gears. In addition, the driven roller can be brought into pressure contact with the driving roller by rotating the arm. Accordingly, the sheet can be fed out by the nip pressure between the driving roller and the driven roller, and the sheet can be drawn onto the reverse tray. After that, if the knob stops, the arm rotates again in the separating direction by the separating means, and the nip pressure of the sheet is released, so that the sheet can be easily removed from the reverse tray and jammed. It can be done easily.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of an image forming apparatus capable of duplex printing according to the present invention. In this figure, the same parts as those in the conventional image forming apparatus shown in FIG. 4 are denoted by the same reference numerals, and detailed description thereof is omitted.

  Next, the configuration of the switchback device 7 in the image forming apparatus capable of duplex printing according to the present invention will be described in detail with reference to FIGS.

  The switchback device 7 includes a reversing tray 70, a driving roller 711 provided on the lower side of the paper conveying surface of the reversing tray 70, and a contact with the driving roller 711 on the upper side of the paper conveying surface of the reversing tray 70. A switchback roller pair 71 comprising a driven roller 712 that is freely press-contacted, and a switchback roller driving means (not shown) for rotating the drive roller 711 in either the forward rotation or the reverse rotation, are provided rotatably. The arm 73 that supports the driven roller 712, a biasing spring (biasing means) 76 that biases the arm 73 in the pressure-contact direction, and the arm 73 against the biasing by the biasing spring 76 during jam processing. Is provided with a separation / contact solenoid (separation means) 75 for rotating the jam, and a jam processing knob 80 fixed to the rotation shaft 74 of the arm 73.

  More specifically, reference numeral 77 denotes an arm support member that forms a conveyance path in which the inclined surface of the bottom portion extends from the upstream conveyance path 25 to the reverse tray 70. A pair of support pieces 77 a that have round holes that pass through and face each other in a direction orthogonal to the paper transport direction are provided on both side ends of the arm support member 77. The arm 73 has a rotating shaft 74 passing through the upstream end in the sheet conveying direction in a direction perpendicular to the sheet conveying direction, and the rotating shaft 74 is inserted into the round hole of the support piece 77a. Thus, the arm support member 77 is rotatably supported. The arm 73 supports a driven roller 712 at the downstream end in the paper transport direction. The driven roller 712 has a face on the reversing tray 70 through an opening provided on the horizontal plane at the bottom of the arm support member 77 and is in pressure contact with the driving roller 711. The urging spring 76 is installed between the ceiling surface of the arm support member 77 and the upper surface of the upstream end portion of the arm 73 in the sheet conveyance direction, and urges the arm 73 in the press-contact direction.

  Further, gears 781 and 782 that mesh with each other are arranged on the rotation shaft 74 of the arm 73 and the rotation shaft 72 of the driven roller 712, respectively. Further, a torque limiter (torque increasing means) 79 is provided on the rotating shaft 72 of the driven roller 712. The torque limiter 79 is fitted between the rotation shaft 72 of the driven roller 712 and the inner periphery of the gear 782 disposed on the driven roller 712. By providing such a torque limiter 79, it is possible to increase the rotational torque of the gears 781 and 782 as compared with the case where the torque limiter 79 is not provided.

  Next, as described above, in a state where the paper is engaged with the pair of entrance rollers 251 and 252 and the switchback roller pair 71, a paper jam (jam) occurs between the upstream conveyance path 25 and the switchback device 7. The jam processing procedure in the case of occurrence will be described.

  First, the knob 80 is rotated clockwise (in the direction of arrow A in FIG. 2) to transmit the rotation of the knob 80 to the gear 782 via the gear 781. At this time, as described above, the rotational torque of the gears 781 and 782 is increased by the torque limiter 79, so that a force is applied in the press-contact direction (the direction of arrow B) to the gear 782 at the meshing portion between the gears 781 and 782. In addition, as shown by an arrow X in FIG. 3, the arm 73 rotates around the rotation shaft 74, whereby the driven roller 712 can be brought into pressure contact with the drive roller 711. Note that the amount of increase in rotational torque of the gears 781 and 782 can be freely adjusted according to the characteristics of the torque limiter 79 to be used. As the amount of increase in rotational torque is increased, a greater pressure contact force can be obtained.

  Then, the gear 782 rotates counterclockwise (in the direction of arrow C) to forcibly rotate the driven roller 712 in the same direction via the rotating shaft 72, and the paper P is sandwiched by the nip pressure of the switchback roller pair 71. The sheet sandwiched between the feeding and entry roller pairs 251 and 252 can be drawn onto the reverse tray 70. Since the separation solenoid 75 is still operating during this time, if the rotation of the knob 80 is stopped, the arm 73 is rotated again in the separation direction by the separation solenoid 75 and the nip of the paper P is released. In addition, the paper P can be extracted from the reversing tray 70, and jamming can be easily performed.

  The present invention is not limited to the above embodiment, and various modifications are possible. For example, the example in which the torque limiter is used as the torque increase means of the driven roller has been described. However, the present invention is not limited to this, and any apparatus that functions as torque increase means such as an elastic bush may be used. Moreover, although the example which uses the contact / separation solenoid as the arm contact / separation means has been described, other means (for example, an electromagnet) may be used as long as the mechanism rotates the arm in the contact / separation direction at the time of jam processing. it can. Further, an example in which an urging spring is used as the urging means of the arm will be described, and the drawing shows an example in which the urging spring is a coil spring. However, the present invention is not limited to this, and other types of springs (for example, leaf springs) Alternatively, an urging means (for example, a magnet) that does not rely on a spring may be used.

  The present invention can be used in an image forming apparatus having a double-sided printing function such as a copying machine.

FIG. 2 is a schematic view of a switchback device of an image forming apparatus capable of double-sided printing according to the present invention. These are perspective views of the switchback device of the present invention. These are sectional views of the switchback device of the present invention. FIG. 2 is a schematic view of a switchback device of a conventional image forming apparatus capable of duplex printing. FIG. 3 is a perspective view of the conventional switchback device.

Explanation of symbols

7 Switchback Device 25 Upstream Conveying Path 70 Reverse Tray 71 Switchback Roller Pair 711 Drive Roller 712 Driven Roller 72 Rotating Shaft 73 Arm 74 Rotating Shaft 75 Separation / Contact Solenoid 76 Energizing Spring 77 Arm Support Member 781, 782 Gear 77a Support Piece 79 Torque limiter 80 Knob 251 252 Pair of entrance rollers

Claims (3)

  A driving roller that is driven to rotate forward and backward, a driven roller that is press-contacted to the driving roller so as to be detachable, an arm that is pivotally supported to support the driven roller, and the arm is attached to the pressing direction. An urging means for urging, a detaching means for rotating the arm against urging by the urging means at the time of jam processing, and a jam processing knob fixed to a rotation shaft of the arm. And a gear increasing means for increasing the rotational torque of the gear by the rotation of the knob during jam processing, wherein gears meshing with the rotation shaft of the arm and the rotation shaft of the driven roller are arranged, respectively. A switchback device for an image forming apparatus capable of duplex printing.   2. The switchback device of an image forming apparatus capable of duplex printing according to claim 1, wherein the torque increasing means comprises a torque limiter attached to a rotating shaft of the driven roller.   3. The image forming apparatus capable of duplex printing according to claim 2, wherein the torque limiter is fitted between a rotation shaft of the driven roller and an inner periphery of a gear disposed on the driven roller. Switchback device.

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