JP2012106868A - Sheet conveyance apparatus, and image forming apparatus with the same such as electrophotographic copying apparatus, printing apparatus, fax apparatus and digital multifunction apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet conveyance apparatus that can optimally guide a sheet into an inverting carrying-in roller, thereby improving conveyance performance while preventing unnecessary contact with the inverting carrying-in roller by guiding the sheet or a recording material by a roller guide roller.SOLUTION: The sheet conveyance apparatus includes: the plurality of inverting carrying-in rollers 9 that are provided in a branching point of an entrance and exit of a switchback inverting part and carry the sheet P in the switchback inverting part from the entrance thereof; and the roller guide roller 17 that is located near either one side or both sides of the inverting carrying-in roller located in the outermost end side in an axial direction of the plurality of inverting carrying-in rollers 9. An outer circumferential surface of the roller guide roller 17 is formed to have a lower frictional force in comparison with the sheet P. Accordingly, the unnecessary contact of the sheet P with the inverting carrying-in roller 9 can be prevented when the switchback of the sheet P is performed.

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a digital multi-function machine that combines these functions, and a sheet conveying apparatus used for these.

  FIG. 1 is a cross-sectional view of a general image forming apparatus, and shows a conveyance path of paper and a recording material (hereinafter simply referred to as paper, but also includes a recording material made of a material other than paper).

  When forming an image on one side with the illustrated image forming apparatus 1, the paper P stacked on the paper feeding unit 3 is fed, the image is transferred on one side by the image forming unit 2, and the image is fixed by the fixing unit 4. It is discharged to the reversing unit 6, switched back and reversed by the reversing unit 6, and discharged through the paper discharge unit 8.

  In this type of image forming apparatus, when images are formed on both sides, the paper P stacked on the paper feeding unit 3 is fed, the image is transferred to one side by the image forming unit 2, and the image is fixed by the fixing unit 4. The image is discharged to the reversing unit 6, switched back and reversed by the reversing unit 6, fed again through the duplex feeding path 7, transferred to the back side by the image forming unit 2, and fixed by the fixing unit 4. The image is fixed and discharged through the paper discharge unit 8. When forming an image on only one side without forming an image on both sides, the paper P stacked on the paper feeding unit 3 is fed, and an image is transferred to the one side by the image forming unit 2, and the image is fixed by the fixing unit 4. Then, the paper is discharged through the paper discharge unit 8. In the figure, 5 is a paper transport unit, 41 is a paper transport roller pair, 16 is a paper discharge direction switching unit, 15 is a double-sided turn roller, and 17 is a paper transport direction switching unit.

  FIG. 2 is a main configuration diagram of the reversing unit and its periphery of the apparatus of FIG. The sheet P on which the image has been transferred and fixed is conveyed to the reversing unit 6. In the reversing unit 6, a pair of a carry-in roller 9 that carries the paper P from the entrance of the reversing unit 6 to the reversing unit 6 and a conveying claw 10 (hereinafter referred to as a reverse carrying-in roller 9 and a reversing conveying claw 10 respectively) 11 is released. The individual claws of the reverse conveying claw 10 having a comb tooth shape and the rollers of the reverse conveying roller 9 having a dumpling shape are alternately positioned. As shown in FIG. 3, the reverse conveying roller 9 and the reverse conveying claw 10 The paper is carried into the reversing table 11 by the pressure applied to the reversing carry-in roller 9 caused by the stiffening of the paper due to the generated wavy shape. As shown in FIG. 4, when the reverse conveyance claw 10 and the reverse carry-in roller 9 carry in the paper, the force for pressing the paper P is adjusted by the pressure spring 23. In the figure, reference numerals 22a and 22b denote guide members for guiding the sheet P to enter the reverse carry-in roller 9.

  A jogger fence pair 12 for adjusting the position and posture of the paper P is provided on the reversing table 11 and is movable in the direction perpendicular to the paper surface of FIG. A jog operation is performed to move the paper P discharged on the reversing table 11 to a position where the jogger fence pair 12 waiting in a position wider than the paper width to receive the paper P guides the paper. To guide. With the jogger fence 12 guiding the paper, the reverse driven roller 13 that has been moved upward is lowered, pressed against the reverse rotation driving roller 14 to switch back the paper P, and carried to the double-sided turn roller 15 side. To do. In the figure, 34 is a turn branch claw, 35 is a reverse intermediate roller, 36 is a driven inlet roller, and 37 is a driven outlet roller.

  Thereafter, the reverse driven roller 13 is lifted to release the pressure contact with the reverse drive roller 14. When an image is formed on only one side of the paper P, the paper P is sent to the paper discharge unit and discharged outside the image forming apparatus. At both sides, the double-sided turn roller 15 turns the paper and conveys it to the double-sided feeding path 7. The duplex feeding path 7 conveys the sheet to the relay rollers 26, 27, and 28 and is fed again to the image forming unit 2.

  FIG. 5 is a perspective view showing the reverse carry-in roller 9 and the reverse conveyance claw 10 as described above. In order to suppress time loss due to the paper P1 carried into the reversing table 11 and the papers P1 and P2 carried out from the reversing table 11 passing each other (see FIGS. 6 and 7), a motor common to others is used. The reverse carry-in roller 9 is rotated in one direction (arrow C direction in the figure). Moreover, in order to generate a corrugated shape as shown in FIG. 3, the reverse conveying claw 10 is lifted and biased upward in the drawing as shown in FIG. 4, and the tip portion of the reverse conveying claw 10 is the outer periphery of the reverse carrying roller 9. The reversing and loading roller 9 is configured such that a part 9 a of the reversing and loading roller 9 protrudes below the reversing and conveying claw 10. Therefore, when the paper is fed onto the reversing table 11 as shown in FIG. 6, the reversing conveyance claw 10 is pushed down by the paper P, so that the above-mentioned portion 9a does not occur or even if it occurs slightly, there is no problem in the conveyance of the paper P. When the paper P is switched back as described above, if the corner portion of the paper P is greatly curled as shown in the figure, the leading end portion P1 of the curled paper P is moved in the carry-out direction (arrow X in the figure). ) In contact with the reverse carry-in roller 9 rotating in the opposite direction (arrow C direction), and more specifically, the portion 9a protruding downward of the reverse carry claw 10, and further curled up, which is jammed or paper Can cause damage (breaks, broken ears, etc.). That is, the conveyance quality of the paper can be reduced.

  In an image forming apparatus having heat-based fixing, there is a high possibility that the paper curls after fixing, and the paper P may be curled by an image formed with toner.

  In the conventional apparatus configuration, the reverse carry-in roller is driven by using a dedicated drive source, or by using the drive source of the paper feeding unit different from the read conveyance to perform forward / reverse rotation in the document conveyance direction. Yes. For this reason, a drive source increases and cost becomes high.

  The present invention has been made in view of the above-described conventional problems, and is capable of preventing damage to jams and paper at a low cost with a simple mechanism, and an image forming apparatus including the same. An object of the present invention is to provide an electrophotographic copying machine, a printer, a facsimile machine, and a digital multifunction machine.

  The sheet conveying apparatus of the present invention is arranged such that the rotation center is located at a position deviated from the paper or recording material carry-in path to the switchback reversing unit, and the outer peripheral surface enters the carry-in path. A carry-in roller that rotates in the direction of carrying a sheet or recording material from the entrance of the reversing unit to the switchback reversing unit, a roller guide roller located near one side or both sides of the end surface of the carry-in roller, and a sheet or recording material The coefficient of friction of the roller guide roller is lower than the coefficient of friction of the carry-in roller with respect to the sheet or recording material.

  According to the present invention, the roller guide roller guides the paper and the recording material to prevent unnecessary contact with the reverse carry-in roller, and the paper guide to the reverse carry-in roller can be optimized. This has the effect of improving the conveyance performance.

Cross-sectional view of a general image forming apparatus 1 is a main configuration diagram of the reversing unit and its periphery of the apparatus of FIG. The figure which shows the conveyance form of the paper with the wave shape The figure which shows the paper carrying-in structure by the conveyance nail | claw and the reverse carrying-in roller in the apparatus of FIG. 4 is a perspective view of the structure of FIG. FIG. 4 is a diagram illustrating a paper carry-in state with the structure of FIG. FIG. 4 is a diagram of a paper switchback state according to the structure of FIG. 1 is a configuration diagram of a reverse carry-in roller and a roller guide roller in an embodiment of a sheet conveying apparatus according to the present invention. FIG. 8 is a diagram of a paper switchback start state according to the embodiment of FIG. FIG. 8 is a diagram of a state after the start of paper switchback according to the embodiment of FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the embodiments shown in the drawings.

  FIG. 8 is a configuration diagram of the reverse carry-in roller and the roller guide roller in the embodiment of the sheet conveying apparatus according to the present invention. FIG. 8 is a perspective view corresponding to FIG. 5 showing a conventional example, and the roller used in this example. It is an expanded sectional view (B) which shows a guide roller.

  The roller guide roller 17 is a low-friction member made of a material having good slidability. The roller guide roller 17 is provided on the shaft 19 of the reverse carry-in roller 9 coaxially and in the vicinity of the reverse carry-in roller 9 so as to freely rotate forward and backward. It can be rotated forward and backward. That is, the rotation of the reverse loading roller 9 is not interlocked. On the same axis as the reverse carry-in roller 9, between the reverse carry-in roller 9 and the side surface of the roller guide roller 17, the sliding property is thin and good (for example, about 0.1 mm to 0.2 mm, The thinner one is preferable.) A sliding sheet 20 is provided. The sliding sheet 20 is basically not related to the operation of the reverse loading roller 9 and the roller guide roller 17 and is free. However, there is a possibility that it will be accompanied by contact, but there is no particular problem even if such an operation is performed. Depending on the material of the reverse loading roller 9 and the roller guide roller 17, the sliding sheet 20 may not be provided. If the thickness is too thick, the conveyance mode of the paper P as shown in FIG. 3 may not be obtained.

  In the illustrated example, the roller guide roller 17 is combined with all the axially opposite sides except for the central reverse carry-in roller 9, but the reverse carry-in roller 9 is the end of the sheet of any size conveyed by the apparatus. Various arrangements such as providing the reversal loading roller 9 on the outer side in the axial direction (located in the vicinity of the end of the sheet) that conveys the vicinity of the portion may be employed. Therefore, the present invention is not limited to the illustrated configuration and arrangement.

  In particular, when the paper size is large, the curl of the paper tends to increase. Therefore, it is costly to provide the roller guide roller 17 in combination only with the reverse conveying roller 9 located near the end of the large size paper. May be advantageous.

  The outer diameter of the roller guide roller 17 is slightly smaller than the outer diameter of the reverse carry-in roller 9 (for example, about 0.1 mm; however, it may be determined depending on the properties of the paper to be used). Thus, the paper P comes into contact only with the outer diameter surface (outer peripheral surface) of the reverse carry-in roller 9 that is a surface on which the paper P needs to be carried in, and contact with other unnecessary portions is prevented.

  Of course, there is a hole in the portion where the roller guide roller 17 is rotatably mounted on the shaft 19 of the reverse carry-in roller 9, that is, the central portion through which the shaft 19 penetrates. In order to prevent this, the bearing portion 17a of the roller guide roller 17 is sufficiently long (for example, 15 to 20 mm in a general image forming apparatus, but the length may be determined according to the apparatus configuration). It is formed in the shape of a bearing. The shaft 19 is provided with a groove portion, and a stopper 21 is attached to the groove portion so that the bearing portion 17a of the roller guide roller 17 does not move in the axial direction of the shaft 19. That is, since the attachment part of the roller guide roller 17 to the shaft 19 is long, the position of the roller guide roller 17 can be stabilized and the conveyance performance can be stabilized.

  Moreover, the part rotatably attached to the axis | shaft of the reverse carrying-in roller 9 may have a bearing so that rotation may become smoother. In image forming devices, curling is likely to occur due to heat fixation and toner images. However, these single or combined configurations prevent paper damage such as jamming and ear folding due to paper curl and improve transport performance stably. is doing.

  When the paper P is carried in, it is assumed that the one end portion P1 is warped. If the sheet is conveyed as it is, the warpage becomes severe as in the conventional example, and the reverse carry-in roller 9 comes into contact with the sheet P appropriately and the sheet P cannot be carried out. However, in this embodiment, the roller guide roller 17 functions so that the warped end portion P <b> 1 of the paper P does not unnecessarily contact the reverse carry-in roller 9.

  Specifically, as shown in FIG. 9, if the end portion P1 of the paper P is warped during switchback, the edge of the end portion P1 may come into sliding contact with the roller guide roller 17. Since the roller guide roller 17 is made of a low friction member, when the end portion P1 of the paper P comes into contact with the edge of the roller guide roller 17, the behavior of the paper P that warps upward is suppressed, and the downward force against the force of warping upward is reduced. Receives reaction force x1. Thereby, the curling of the paper P is suppressed regardless of the rotation or non-rotation of the roller guide roller 17, and even if the upper surface of the paper P is in contact with the roller guide roller 17, it is counteracted along the edge of the roller guide roller 17. As shown in FIG. 10, it moves in the conveyance direction so that it slips, enters the lower side of the tip of the reverse conveyance claw 10, and conveys it to the double-sided feed path without causing curling or curling. As a result, the conveyance performance is improved.

  At this time, if the upper surface of the paper P is in contact with not only the edge of the roller guide roller 17 but also the lower edge of the reverse conveying claw 10, the reaction force x1 as described above due to the edge of the roller guide roller 17 is applied to the upper surface of the paper P. In addition to this, as a reaction force against the force by the end portion P1 of the paper P trying to push up the lower edge of the reverse conveyance claw 10, a downward reaction force x2 is applied and the paper is smoothly conveyed to the duplex feeding path. become. However, the reaction force x2 is not so large because the reverse conveying claw 10 is biased upward as described above.

  It should be noted that deformation such as rounding of the sheet P in the conveyance direction can occur not only at the edge of the sheet P but also at other parts such as the center of the sheet P. In this embodiment, since the roller guide roller 17 is combined not only with the reverse carry-in roller 9 at the end as shown, but also with the reverse carry-in roller 9 inside, as in the behavior at the end described above, The paper P is smoothly transported to the duplex feeding path. Further, even for a paper with a large curl, it is possible to reliably prevent the ear folding due to the paper curl at a low cost.

  That is, the roller guide roller 17 can freely rotate forward and backward, and is not interlocked with the rotation of the reverse carry-in roller 9, so that the roller guide roller 17 freely rotates even if the paper P contacts the roller guide roller 17. However, since the load resistance to the paper P is low and the paper P can be guided, even when the paper P has a lot of curl, it is possible to suppress the occurrence of conveyance problems such as jamming and folding due to rounding, and the conveyance performance is further improved at a low cost. it can.

  In addition, the thin sliding sheet 20 prevents the roller guide roller 17 and the reverse loading roller 9 from contacting each other, so that the roller guide roller 17 can be rotated smoothly, the load resistance on the paper P is reduced, and the paper P is rounded. It is possible to accurately suppress the occurrence of jamming, folding, and other conveyance problems, and to easily reduce the space between the roller guide roller 17 and the reverse loading roller 9 to be narrow and space-saving, thereby further improving the conveyance performance. be able to.

  In addition, by forming the outer diameter of the roller guide roller 17 to be the same as or slightly smaller than the outer diameter of the reverse carrying-in roller 9, the width of the roller guide roller 17 is reduced and space is saved, so that unnecessary portions of the reverse carrying-in roller 9 are eliminated. The conveyance performance can be improved by preventing the paper P from coming into contact with the paper.

  If the sheet conveying device as described above is used in the image forming apparatus, the roller guide roller has a space-saving conveyance quality even under conditions where image transfer and fixing are likely to cause paper curling. Can be improved.

  Although not shown, a roller guide roller 17 may be provided on both sides of one reverse loading roller 9.

1: Double-sided image forming apparatus 2: Image forming unit 3: Paper feeding unit 4: Fixing unit 5: Paper feeding / conveying unit 6: Reversing unit 7: Double-sided feeding path 8: Paper discharging unit 9: Reverse carry-in roller 9a: Reverse carry-in Part of roller 10: Reverse conveyance claw 11: Reverse table 12: Jogger fence pair 13: Reverse driven roller 14: Reverse drive roller 15: Turn roller 16: Reverse discharge path 17: Roller guide roller 17a: Bearing portion 18: Sliding Sheet 19: Shaft 20: Sliding sheet 21: Retaining ring 22: Entrance guide plate 23: Pressure springs 26, 27, 28: Relay roller 34: Turn branch claw
35: reverse intermediate roller 36: driven inlet roller 37: driven outlet roller 41: registration roller pair P, P1, P2: paper X: transport direction x1, x2 at the time of paper switchback: reaction force

JP-A-11-143138

Claims (10)

The rotation center is located at a position away from the paper or recording material carry-in path to the switchback reversing unit, and the outer peripheral surface is disposed so as to enter the carry-in path. A carry-in roller that rotates in a direction to carry paper or recording material into the reversing unit;
A roller guide roller located near one side or both sides of the end surface of the carry-in roller;
The friction coefficient of the roller guide roller with respect to the paper and recording material is lower than the friction coefficient of the carry-in roller with respect to the paper and recording material.
A sheet conveying apparatus characterized by that. The rotation center is located at a position away from the paper or recording material carry-in path to the switchback reversing unit, and the outer peripheral surface is disposed so as to enter the carry-in path. A plurality of carry-in rollers for carrying paper and recording material to the reversing unit;
A roller guide roller located near one side or both sides of an end face of at least one reverse loading roller among the reverse loading rollers positioned on the outermost end side in the axial direction of the plurality of reverse loading rollers;
When the friction coefficient of the roller guide roller with respect to the paper or the recording material is made lower than the friction coefficient of the reverse carrying-in roller with respect to the paper or the recording material, and the paper or recording material is switched back, Having a structure that prevents unnecessary contact of the recording material,
A sheet conveying apparatus characterized by that. In the sheet conveying apparatus according to claim 2,
A conveyance claw is provided between the plurality of carry-in rollers,
A sheet conveying apparatus, wherein a leading end of the conveying claw is disposed between the plurality of carrying-in rollers so as to enter the carrying-in path.   4. The sheet conveying apparatus according to claim 2, wherein the roller guide roller is provided so as to correspond to a carry-in roller located in the vicinity of a width end of a sheet to be conveyed or a recording material among the carry-in rollers. .   5. The sheet conveying device according to claim 2, wherein the roller guide roller is provided so as to correspond to a carry-in roller located in the vicinity of a portion of the carry-in roller where a sheet to be conveyed or a recording material may be wavy. A sheet conveying apparatus that is characterized.   6. The sheet conveying apparatus according to claim 2, wherein an outer diameter of the roller guide roller is formed to be equal to or slightly smaller than an outer diameter of a carry-in roller located in the vicinity of the roller guide roller among the carry-in rollers. A sheet conveying apparatus comprising: In the sheet conveying apparatus according to any one of claims 1 to 6,
The roller guide roller is arranged coaxially with the carry-in roller, and is provided so as to be freely rotatable with respect to the shaft of the carry-in roller, so that it can be rotated forward or reverse regardless of the rotation direction of the carry-in roller. A sheet conveying apparatus. In the sheet conveying apparatus according to any one of claims 1 to 7,
A sheet conveying apparatus, wherein a sliding material for preventing contact between the roller guide and the carry-in roller is disposed between the roller guide roller and the carry-in roller.   9. The sheet conveying apparatus according to claim 8, wherein the sliding member is made of a sheet material that is thinner than the reverse loading roller. An image forming apparatus comprising the sheet conveying device according to claim 1.