JP6424857B2 - Sheet feeding apparatus and image forming apparatus provided with the same - Google Patents

Description

  The present invention relates to a sheet feeding apparatus and an image forming apparatus including the sheet feeding apparatus, and more particularly to a sheet including a sheet storage cassette having a lift mechanism for raising and lowering a sheet stacking plate, and a body gear transmitting a driving force to the lift mechanism. The present invention relates to a feeding device and an image forming apparatus provided with the same.

  A sheet feeding cassette (sheet storage cassette) is used to feed cut paper or the like in an image forming apparatus represented by a copying machine or a printer. In this paper feed cassette, a large number of sheets of paper before printing are stocked in advance, and from the uppermost layer of a bundle of sheets stacked in the paper feed cassette by a paper feed roller and a pickup roller provided near the paper feed cassette. Separately feed sheets one by one.

  Further, there is a sheet feeding cassette provided with a sheet stacking plate on which a sheet is placed on the upper surface. The sheet stacking plate has an upstream end supported on the inner side of the bottom surface of the sheet feeding cassette, and can be pivoted about the fulcrum with a downstream end on the sheet feeding direction as a pivoting end. Further, the sheet feeding cassette is provided with a lift mechanism that raises and lowers the rotating end of the sheet stacking plate. A driving force is transmitted to the lift mechanism via a main body gear provided in the image forming apparatus main body, an input gear provided in a cassette side surface portion of the paper feed cassette, and the like.

  An image forming apparatus that rotates a sheet stacking plate by transmitting driving force from a main gear provided in an image forming apparatus main body to a lift mechanism of a sheet feeding cassette and driving the lift mechanism is disclosed in, for example, Patent Document 1 It is disclosed.

JP, 2009-40517, A

  By the way, in order to smoothly carry out loading and unloading of the sheet feeding cassette with respect to the image forming apparatus main body, some play (gap) may be provided between the main body rail portion of the image forming apparatus main body and the sheet feeding cassette. In this case, when the driving force is transmitted from the main gear of the image forming apparatus main body to the input gear of the sheet feeding cassette, the force applied to the input gear from the main gear deforms the shaft of the input gear and the input gear becomes the main gear. It is easy to displace in the direction away from the For this reason, there is a problem that the engagement between the main gear and the input gear is likely to be disengaged (the teeth are likely to jump).

  Also, a boss may be integrally formed on the side surface portion of the sheet cassette, and an idle gear disposed downstream of the input gear or the input gear may be rotatably supported by the boss. In this case, when the driving force is transmitted from the main gear of the image forming apparatus main body to the input gear of the sheet feeding cassette, the boss is broken by the force applied to the input gear and the idle gear.

  The present invention has been made to solve the problems as described above, and the object of the present invention is to suppress the occurrence of the meshing failure of the gear and to prevent the boss for supporting the gear from being broken. SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet feeding apparatus capable of image forming and an image forming apparatus provided with the sheet feeding apparatus.

  In order to achieve the above object, a sheet feeding apparatus according to a first aspect of the present invention is detachable from a cassette mounting section of an apparatus main body, and includes a sheet storage section for storing a sheet, and a sheet storage section. A sheet stacking plate on which the upstream side of the sheet feeding direction is rotatably supported and a sheet is placed on the upper surface, a lift mechanism for moving the sheet stacking plate up and down, and extends in a mounting and removing direction to form a sheet storage portion A sheet storage cassette having an input gear disposed on the outer surface of the cassette side surface, and an idle gear disposed on the outer surface of the cassette side surface to transmit the driving force from the input gear to the lift mechanism; And a main body gear provided on the main body side surface facing the cassette side surface, engaged with the input gear, and transmitting the driving force to the lift mechanism through the input gear and the idle gear. The cassette side face portion is formed with a boss projecting toward the outside of the sheet storage portion, and at least one of the input gear and the idle gear is rotatably supported by the boss, and the body side face portion While the sheet storage cassette is mounted on the apparatus main body, a support portion is provided which supports the tip of the boss and positions the sheet storage cassette at a predetermined position with respect to the apparatus main body via the boss.

  According to the sheet feeding apparatus in accordance with the first aspect of the present invention, at least one of the input gear and the idle gear is rotatably supported by a boss formed on the side surface of the cassette, In the case where the sheet storage cassette is attached to the apparatus main body, a support portion for supporting the tip end portion of the boss is provided. Accordingly, when the driving force is transmitted from the main gear to the input gear, the support portion can suppress displacement of the boss due to the force applied to the input gear and the idle gear. Therefore, it is possible to suppress the engagement (jumping) of the engagement between the main body gear and the input gear and the engagement between the input gear and the idle gear.

  In addition, since the displacement of the boss due to the force applied to the input gear and the idle gear when the driving force is transmitted from the main gear to the input gear can be suppressed, the breakage of the boss can be suppressed. it can.

  In addition, since the support portion positions the sheet storage cassette at a predetermined position with respect to the apparatus main body via the boss, the positioning accuracy of the sheet storage cassette with respect to the apparatus main body can be improved.

  Further, since the support portion for supporting the boss is provided on the device body, the boss can be positioned with respect to the device body. As a result, the positioning accuracy of the input gear and the idle gear with respect to the device body can be improved, so that the engagement between the main gear and the input gear and the engagement between the input gear and the idle gear (disengagement) can be prevented. It can suppress more.

FIG. 1 is a cross-sectional view showing a structure of an image forming apparatus provided with a sheet feeding device according to an embodiment of the present invention. FIG. 6 is a perspective view showing the structure of a portion of the sheet feeding cassette of the embodiment of the present invention on the downstream side in the sheet feeding direction of the sheet feeding cassette. FIG. 3 is a perspective view showing the sheet feeding cassette of the sheet feeding device of the embodiment of the present invention from the downstream side in the sheet feeding direction. FIG. 6 is a perspective view showing a structure of a portion of the sheet feeding cassette of the sheet feeding device according to the embodiment of the present invention on the downstream side in the sheet feeding direction and around the positioning portion of the image forming apparatus main body. FIG. 5 is a side view showing the structure around the input gear of the sheet feeding cassette of the sheet feeding device of the embodiment of the present invention. FIG. 8 is a perspective view showing the structure of the sheet stacking plate and the lift mechanism of the sheet feeding cassette of the sheet feeding device according to the embodiment of the present invention, in which the free end of the sheet stacking plate is positioned at the lowermost position. is there. FIG. 8 is a perspective view showing the structure of the sheet stacking plate and the lift mechanism of the sheet feeding cassette of the sheet feeding device according to the embodiment of the present invention, in which the free end of the sheet stacking plate is lifted by the push-up plate. . FIG. 8 is a side view showing the structure around the input gear of the sheet feeding cassette of the sheet feeding device according to the embodiment of the present invention, and a view showing a state in which a cover member is attached to a wall. FIG. 6 is a cross-sectional view showing the structure of the input gear of the sheet feeding cassette of the sheet feeding device of the embodiment of the present invention. FIG. 6 is a cross-sectional view showing a structure of an idle gear of the sheet feeding cassette of the sheet feeding device of the embodiment of the present invention. FIG. 6 is a plan sectional view showing the structure around the idle gear of the sheet feeding cassette of the sheet feeding device of the embodiment of the present invention. FIG. 6 is a perspective view showing the structure around the input gear of the sheet feeding cassette of the sheet feeding device of the embodiment of the present invention. FIG. 2 is a perspective view showing a structure around a main gear of a sheet feeding device according to an embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  An image forming apparatus 100 including a sheet feeding device according to an embodiment of the present invention will be described with reference to FIGS. Here, a monochrome printer is shown as the image forming apparatus 100. As shown in FIG. 1, an image forming portion P for forming a monochrome image in the steps of charging, exposure, development and transfer is disposed in the main body of the image forming apparatus 100.

  In the image forming unit P, the charging unit 2, the exposure unit 3, the developing device 4, the transfer roller 7, the cleaning device 8, and the charge removing device are arranged along the rotational direction of the photosensitive drum 1 (counterclockwise direction in FIG. 1). (Not shown) is provided. In the image forming portion P, an image forming process on the photosensitive drum 1 is performed while rotating the photosensitive drum 1 in the counterclockwise direction in FIG.

  A sheet (sheet) 18 is conveyed from the sheet feeding cassette (sheet storage cassette) 30 at a predetermined timing via the sheet conveyance path 11 and the registration roller pair 13 toward the image forming portion P on which the toner image is formed. In the image forming portion P, the toner image on the surface of the photosensitive drum 1 is transferred onto the sheet 18 by the transfer roller 7. Then, the sheet 18 to which the toner image has been transferred is separated from the photosensitive drum 1, conveyed to the fixing unit 9, and heated and pressed to fix the toner image on the sheet 18.

  The transport direction of the sheet 18 having passed through the fixing unit 9 is sorted by the branch members 16 of the branch portions branched in a plurality of directions. When an image is formed on only one side of the sheet 18, the sheet is discharged to the discharge tray 15 by the discharge roller pair 14 as it is.

  On the other hand, when forming an image on both sides of the sheet 18, the sheet 18 having passed through the fixing unit 9 is once conveyed in the direction of the discharge roller pair 14, and after the rear end of the sheet 18 passes the branch member 16, the discharge roller pair The sheet 14 is distributed to the reverse conveyance path 17 from the rear end of the sheet 18 by reversing the conveyance direction of the branch member 16 while reversing the rotation direction of the branch member 16 and is re-conveyed to the registration roller pair 13 with the image surface inverted. Then, the next image formed on the photosensitive drum 1 is transferred by the transfer roller 7 to the surface of the sheet 18 on which the image is not formed, and conveyed to the fixing unit 9 to fix the toner image. It is discharged to 15.

  The sheet feeding cassette 30 is formed detachably to the main body of the image forming apparatus 100. In the image forming apparatus 100, the sheet conveyance path 11 when a sheet is fed from below the main body of the image forming apparatus 100 on the downstream side (direction of arrow A) of the sheet feeding direction (sheet feeding direction) of the sheet feeding cassette 30. The sheet feeding cassette 30 is pulled out in the left direction (arrow A 'direction) of FIG. That is, the left direction in FIG. 1 is the direction in which the sheet cassette 30 is pulled out, and the right direction is the direction in which the sheet cassette 30 is mounted.

  On the back side (right side in FIG. 1) in the mounting direction of the sheet feeding cassette 30, a feeding unit 20 for feeding the sheet 18 is provided. The feeding section 20 is brought into pressure contact with the uppermost surface of the sheet 18 stacked in the sheet feeding cassette 30 and rotates to rotate the pickup roller 21 for feeding the sheet 18 and a feed roller for conveying the sheet 18 fed from the pickup roller 21. And 22a. A retard roller 22b is in pressure contact with the feed roller 22a, and the two rollers constitute a conveyance roller pair 22. When a plurality of sheets of paper 18 are simultaneously fed by the pickup roller 21, the sheet 18 is fed by the conveyance roller pair 22, and only the uppermost sheet is fed toward the sheet conveyance path 11.

  FIG. 2 is a perspective view showing the structure of the downstream portion of the sheet feeding cassette 30 of the image forming apparatus 100 according to the embodiment of the present invention in the sheet feeding direction. 2 shows a state as viewed from the back side of the paper surface of FIG. 1, and the drawing direction and mounting direction of the sheet cassette 30 are opposite to those in FIG. In FIG. 2, the sheet feeding cassette 30 is formed in a flat box shape having wall portions 32 a to 32 d (see FIGS. 1 and 2) erected on the four peripheral edges of the bottom surface 31. Load and store the sheet 18 from the direction. A sheet storage portion (sheet storage portion) S for storing sheets is formed by the bottom surface 31 and the wall portions 32a to 32d.

  As shown in FIG. 3, on the outside of the wall 32a disposed on the downstream side in the mounting direction of the sheet feeding cassette 30, positioning bosses projecting on the downstream side in the mounting direction on both sides in the sheet width direction perpendicular to the sheet feeding direction. 32e is provided. Further, as shown in FIG. 4, the main body of the image forming apparatus 100 is provided with a positioning portion 101 having a positioning hole into which the positioning boss 32 e is inserted. Thus, when the sheet feeding cassette 30 is attached to the main body of the image forming apparatus 100, the positioning boss 32e is inserted into the positioning hole of the positioning portion 101, and the sheet feeding cassette 30 is in the sheet width direction (direction perpendicular to the arrow AA 'direction. ) Is positioned. At this time, as shown in FIG. 5, the cassette rail portion 33 described later is disposed with a gap (play) in the vertical direction with respect to the main body rail portion 100a.

  As shown in FIG. 2, a pair of cassette rail portions 33 is attached to the outside of the wall portions 32b and 32c parallel to the mounting direction or the pulling-out direction (arrow AA 'direction) of the sheet feeding cassette 30. A pair of main body rail portions 100a (see FIG. 5) for slidably guiding the cassette rail portion 33 is provided on the main body side of the image forming apparatus 100, and the cassette rail portion 33 slides along the main body rail portion 100a. The sheet cassette 30 can be inserted into and withdrawn from the main body of the image forming apparatus 100 by causing the sheet cassette 30 to be inserted.

  A sheet stacking plate (sheet stacking plate) 34 is rotatably provided on the bottom surface 31 of the sheet storage portion S. The sheet bundle is stacked on the sheet stacking plate 34. The sheet stacking plate 34 and the lift mechanism 40 for moving the sheet stacking plate 34 up and down will be described later.

  Inside the sheet feeding cassette 30, a pair of width regulating cursors 35 provided upright along the sheet feeding direction (arrow A direction) is provided. The pair of width regulating cursors 35 can be moved close to and away from each other in the sheet width direction orthogonal to the sheet feeding direction, and contact the side surface of the sheet bundle from both sides in the sheet width direction to position the sheet bundle in the width direction.

  A trailing end regulation cursor (not shown) is provided movably in the sheet feeding direction on the upstream side in the sheet feeding direction inside the sheet feeding cassette 30. A trailing end regulating cursor (not shown) contacts the rear end face of the sheet bundle from the upstream side in the sheet feeding direction, and positions the sheet bundle in the sheet feeding direction.

  As shown in FIG. 6, the sheet stacking plate 34 is supported by a supporting portion (not shown) provided on the upstream side of the side surfaces 32b and 32c in the sheet feeding direction with the end on the upstream side in the sheet feeding direction as a pivot fulcrum 34a. The end on the downstream side in the sheet feeding direction can be turned up and down as the free end 34b. The sheet stacking plate 34 is a plate-like member, and a notch is provided in the movement area of the width regulating cursor 35 and the rear end regulating cursor (not shown).

  In the vicinity of the free end 34 b of the sheet stacking plate 34, a pivot shaft portion 41 is disposed. The pivot shaft 41 is rotatably held by a bearing (not shown) formed on the bottom surface 31 of the sheet feeding cassette 30. The fixing hole 42 a of the push-up plate 42 penetrates through one end of the pivot shaft portion 41, and the pivot shaft portion 41 and the push-up plate 42 are fixed. The push-up plate 42 is disposed at a position opposite to the substantially central portion in the sheet width direction of the back surface of the sheet stacking plate 34, and lifts the sheet stacking plate 34 from below and rotates it. Further, a fan-shaped gear (a push-up gear) 43 is connected to the other end of the rotating shaft portion 41, and the fan-shaped gear 43 rotates together with the push-up plate 42. A lift mechanism 40 is constituted by the pivot shaft portion 41, the push-up plate 42 and the sector gear 43.

  The sector gear 43 is connected to the input gear 51 via an idle gear 50. As shown in FIGS. 2 and 5, the input gear 51 is exposed from the sheet feeding cassette 30, and when the sheet feeding cassette 30 is inserted into the cassette mounting portion of the image forming apparatus 100 main body, the input gear 51 is the image forming apparatus. 100 is engaged with a body gear 25 (see FIG. 5) connected to a lift motor (drive portion) provided on the body side. A sheet feeding device (sheet feeding device) is constituted by the main body gear 25 and the sheet feeding cassette 30.

  When the main gear 25 rotates while the sheet feeding cassette 30 is inserted into the main body of the image forming apparatus 100, the driving force is transmitted to the rotating shaft 41 through the input gear 51, the idle gear 50, and the sector gear 43. By turning the push-up plate 42 as shown in FIG. 7, the rotation side edge 42 b of the push-up plate 42 slides along the back surface of the sheet stacking plate 34, and the free end 34 b of the sheet stacking plate 34 is lifted. To rise.

  The input gear 51 is provided on the outer surface of the wall portion 32 b (cassette side surface portion) so as to be displaceable in a direction in which the input gear 51 contacts and separates from the body gear 25. Specifically, as shown in FIG. 8, the input gear 51 is supported by the wall 32 b and the cover member 36 fixed to the outer surface of the wall 32 b. As shown in FIG. 9, the input gear 51 has a first gear portion 51a having a tooth portion at an outer peripheral portion, and a cylindrical shaft portion 51b integrally formed with the first gear portion 51a. Each of the wall 32 b and the cover member 36 is formed with an elongated hole 37 in which the shaft 51 b of the input gear 51 is supported. The input gear 51 contacts and separates from the main gear 25 and the idle gear 50. It is displaceable in the direction of The long hole 37 extends in the direction in which the input gear 51 is separated from the main gear 25 when the input gear 51 and the main gear 25 contact with each other. Thus, when the tip of the input gear 51 abuts against the tip of the main gear 25 when the sheet feeding cassette 30 is attached to the main body of the image forming apparatus 100, the input gear 51 is along the long hole 37 as shown in FIG. The teeth of the input gear 51 and the main gear 25 can be prevented from being damaged. Further, when the input gear 51 is rotated by obtaining power from the main gear 25, the input gear 51 is displaced in the direction approaching the main gear 25 by the rotating force.

  As shown in FIGS. 5 and 10, the idle gear 50 is provided on the outer surface of the wall 32b and has a second gear 50a having a tooth on the outer periphery and an insertion hole 50b formed in the center. . As shown in FIGS. 5 and 11, on the outer surface of the resin wall portion 32b, a boss 32f that protrudes toward the outside of the sheet storage portion S and is inserted into the insertion hole 50b is integrally formed. The idle gear 50 is rotatably supported by the boss 32f. As shown in FIGS. 8 and 12, the cover member 36 is formed with a perfect circular through hole 38 at a position corresponding to the boss 32f, and the boss 32f is formed on the outside through the through hole 38 of the cover member 36. (It protrudes in the opposite side to wall part 32b).

  As shown in FIG. 13, on the main body side surface portion 100b facing the wall portion 32b of the cassette mounting portion of the image forming apparatus 100 main body, a support portion 102 for supporting the tip end portion of the boss 32f is provided. The support portion 102 is formed in a U-shape in which the direction in which the sheet feeding cassette 30 is pulled out (arrow A 'direction) opens, and the tip of the boss 32 f is mounted in the image forming apparatus 100 main body. Hold the part from above and below.

  In the present embodiment, as described above, the idle gear 50 is rotatably supported by the boss 32f formed in the wall 32b, and the sheet cassette 30 is mounted on the image forming apparatus 100 in the main body side surface 100b. In the state of being mounted on the main body, a support portion 102 for supporting the tip end portion of the boss 32 f is provided. Accordingly, when the driving force is transmitted from the main gear 25 to the input gear 51, the support portion 102 can suppress displacement of the boss 32f due to the force applied to the idle gear 50. Therefore, the engagement between the main gear 25 and the input gear 51 and the engagement between the input gear 51 and the idle gear 50 can be suppressed (jumps).

  Further, since the displacement of the boss 32f due to the force applied to the idle gear 50 when the driving force is transmitted from the main gear 25 to the input gear 51 can be suppressed, the breakage of the boss 32f is suppressed. be able to.

  Further, since the support portion 102 positions the sheet feeding cassette 30 at a predetermined position relative to the main body of the image forming apparatus 100 via the boss 32 f, the positioning accuracy of the sheet feeding cassette 30 relative to the main body of the image forming apparatus 100 is improved. Can.

  Further, since the support portion 102 for supporting the boss 32 f is provided in the main body of the image forming apparatus 100, the boss 32 f can be positioned with respect to the main body of the image forming apparatus 100. Thus, the positioning accuracy of the input gear 51 and the idle gear 50 with respect to the main body of the image forming apparatus 100 can be improved. Therefore, the engagement between the main gear 25 and the input gear 51 and the engagement between the input gear 51 and the idle gear 50 Can be further suppressed.

  Further, as described above, the bosses 32 f penetrate the through holes 38 of the cover member 36 and project outward (toward the support portion 102). As a result, the through hole 38 supports the boss 32f, so that displacement of the boss 32f can be further suppressed. In the configuration in which the boss 32f has a small amount of protrusion and the tip of the boss 32f is supported by the through hole 38, the tip of the boss 32f drops out of the through hole 38 when an external force is applied, causing deformation or breakage of the boss 32f. Occurs.

  Further, as described above, the support portion 102 is formed so as to sandwich the tip end portion of the boss 32 f from above and below while the sheet feeding cassette 30 is mounted on the main body of the image forming apparatus 100. Accordingly, since the bosses 32f can be positioned in the vertical direction with respect to the main body of the image forming apparatus 100, the positioning accuracy of the sheet feeding cassette 30 relative to the main body of the image forming apparatus 100 can be further improved.

  Further, as described above, the lift mechanism 40 includes the push-up plate 42, the sector gear 43 that rotates with the push-up plate 42, and the pivot shaft 41 to which the push-up plate 42 and the sector gear 43 are attached. Thus, by transmitting the driving force from the input gear 51 to the sector gear 43 and rotating the sector gear 43, the sheet stacking plate 34 can be easily moved up and down.

  It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is indicated not by the description of the embodiments described above but by the claims, and further includes all modifications within the meaning and scope equivalent to the claims.

  For example, although the example which applied this invention to the monochrome printer was shown, this invention is not limited to this. Needless to say, various image formations including a sheet storage cassette such as a color printer, a monochrome copier, a color copier, a digital multi-functional peripheral, a facsimile, etc. and a body gear for transmitting a driving force to a lift mechanism of the sheet storage cassette. The present invention can be applied to an apparatus.

  In the above embodiment, the idle gear 50 is supported by the boss 32f. However, the input gear 51 may be supported by the boss 32f, and both the input gear 51 and the idle gear 50 may be two. May be pivotally supported by two bosses 32f.

18 sheets (sheets)
25 body gear 30 paper feed cassette (sheet storage cassette)
32b Wall (cassette side)
32f boss 34 sheet stacking board (sheet stacking board)
36 cover member 38 through hole 40 lift mechanism 41 pivot shaft portion 42 push-up plate 43 sector gear (gear for push-up)
DESCRIPTION OF SYMBOLS 50 idle gear 50a 2nd gear part 50b insertion hole 51 input gear 51a 1st gear part 51b axial part 100 image forming apparatus 102 support part 102b main body side part S sheet storage part (sheet storage part)

Claims (5)

A sheet storage portion which can be attached to and detached from the cassette mounting portion of the apparatus main body, and a portion on the upstream side in the sheet feeding direction is rotatably supported by the sheet storage portion. Sheet stacking plate, a lift mechanism for raising and lowering the sheet stacking plate, an input gear disposed on an outer surface of a cassette side surface portion extending in a mounting and demounting direction forming the sheet storage portion, and an outer surface of the cassette side surface portion A sheet storage cassette having an idle gear, disposed in the drive gear, for transmitting a driving force from the input gear to the lift mechanism;
A main body gear provided on a main body side surface facing the cassette side surface of the cassette mounting portion, engaged with the input gear, and transmitting a driving force to the lift mechanism through the input gear and the idle gear;
Equipped with
The cassette side surface portion is formed with a boss projecting toward the outside of the sheet storage portion,
At least one of the input gear and the idle gear is rotatably supported by the boss;
The main body side surface portion supports the leading end portion of the boss in a state where the sheet storage cassette is mounted to the apparatus main body, and the sheet storage cassette is at a predetermined position with respect to the device main body via the boss. What is claimed is: 1. A sheet feeding apparatus comprising: A cover member attached to an outer surface of the cassette side surface portion so as to sandwich the input gear and the idle gear with the cassette side surface portion;
The sheet feeding apparatus according to claim 1, wherein the boss protrudes through the through hole of the cover member toward the support portion.   The said support part is formed in the state which mounted | worn the said sheet storage cassette to the said apparatus main body, and it is formed so that the front-end | tip part of the said boss may be clamped from upper direction and lower direction. Sheet feeding device.   The lift mechanism includes a push-up plate that lifts and turns the sheet stacking plate from the lower side, a push-up gear that transmits driving force from the input gear and rotates with the push-up plate, the push-up plate and the push-up. The sheet feeding device according to any one of claims 1 to 3, further comprising: a rotation shaft portion to which a gear is attached.   An image forming apparatus comprising the sheet feeding device according to any one of claims 1 to 4.

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