SHEET FEEDING APPARATUS AND IMAGE FORMING APPARATUS

Abstract

A sheet feeding apparatus includes: a stacking portion on which a sheet is stacked; a sheet feeding portion configured to feed the sheet stacked on the stacking portion; a rotating member provided on a downstream side of the stacking portion in a feeding direction of the sheet and rotates in a direction opposite to the feeding direction; a slope portion of which at least a part is provided on the downstream side of the stacking portion in the feeding direction and on an upstream side of the rotating member, and which is inclining so that the downstream side in the feeding direction become an upper side; and a changing unit configured to change a protruding amount of the rotating member toward a sheet feeding path of the sheet.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a sheet feeding apparatus which separates stacked sheets one by one and feeds a sheet, and an image forming apparatus which includes the sheet feeding apparatus.

2. Description of the Related Art

In an image forming apparatus, there is provided a sheet feeding apparatus which separates sheets one by one and feeds a sheet to an image forming portion. In such a sheet feeding apparatus, a slope surface portion may be used as a method of separating the sheets one by one. In the apparatus, as illustrated in FIG. 9A, a sheet S stacked on a stacking portion 1 is conveyed by a feeding roller 2, the sheet is caused to butt against the slope surface portion of a separation member 3 on the downstream side of the feeding roller 2, and only one uppermost sheet is separated by a resistance force at that time and fed (U.S. Pat. No. 8,322,707).

Note that, in order to reliably separate overlapped sheets without being separated by the separation member 3 one by one, a sheet return roller 4 is provided on the downstream side in a sheet feeding direction of the separation member 3. The sheet return roller (hereinafter, referred to as a “return roller”) 4 rotates in a direction to return the fed sheet, a sheet S2 on the side of the return roller is returned by the return roller 4, and as illustrated in FIG. 9B, only an uppermost sheet S1 is separated and conveyed to the image forming portion.

However, as described above, in a method of separating the sheets using the separation slope surface portion and the return roller, when a protruding amount of the return roller 4 toward the sheet feeding path side is set to be small as illustrated in FIG. 9C, separation performance is degraded and there has been a case where the overlapping occurs.

In addition, as illustrated in FIG. 9D, when the protruding amount of the return roller 4 toward the sheet feeding path side is set to be large, the separation performance is improved, but there has been a case where damage such as folding occurs in a leading end of the sheet S1 abutting on the return roller 4. For this reason, there has been a need to strictly set and manage the position accuracy of the return roller.

In addition, since an optimal protruding amount at the return roller position toward the feeding path side is different depending on the rigidity or the thickness of the sheet, there has been a problem of having to more strictly manage the position accuracy of the return roller.

SUMMARY OF THE INVENTION

The present invention provides a sheet feeding apparatus which can reliably separate and feed sheets and an image forming apparatus which includes the sheet feeding apparatus.

For this purpose, a representative configuration of the present invention includes: a stacking portion on which a sheet is stacked; a sheet feeding portion configured to feed the sheet stacked on the stacking portion; a rotating member provided on a downstream of the stacking portion in a feeding direction of the sheet and configured to rotate in a direction opposite to the feeding direction; a slope portion of which at least a part is provided on the downstream of the stacking portion in the feeding direction and on an upstream of the rotating member, and which is inclining so that the downstream side in the feeding direction becomes higher; and a changing unit configured to change a protruding amount of the rotating member toward a sheet feeding path of the sheet.

Thereby, it is possible to feed the sheet while preventing the overlapping of the sheets without relying on the position accuracy of the rotating member and without damaging the sheet.

Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram describing an entire configuration of an image forming apparatus.

FIGS. 2A to 2D are diagrams describing a cross section of a sheet feeding apparatus.

FIG. 3 is a plan view describing the sheet feeding apparatus.

FIG. 4 is a control block diagram of an actuator.

FIGS. 5A and 5B are diagrams describing the sheet feeding apparatus which moves a separation member using a cam mechanism.

FIGS. 6A and 6B are diagrams describing the sheet feeding apparatus which switches a rotation direction of a return roller according to a second embodiment.

FIGS. 7A and 7B are diagrams describing an embodiment in which a position of the return roller is made movable.

FIGS. 8A to 8C are diagrams describing an embodiment in which the return roller moves according to the rotation direction of the return roller.

FIGS. 9A to 9D are diagrams illustrating a configuration of a conveying apparatus in the related art.

DESCRIPTION OF THE EMBODIMENTS

Next, a sheet feeding apparatus according to embodiments of the present invention and an image forming apparatus including the sheet feeding apparatus will be described with reference to the drawings.

First Embodiment

Image Forming Apparatus

An entire configuration of an image forming apparatus which includes a sheet feeding apparatus according to a first embodiment of the present invention will be described with reference to FIG. 1.

FIG. 1 is a schematic cross-sectional view of the image forming apparatus. An image forming apparatus A includes, when it is roughly divided, a sheet feeding apparatus B which feeds a sheet S from a stacking portion, and an image forming portion which forms a toner image on the fed sheet S. Then, the image forming portion includes an image transfer portion C which transfers the toner image onto the sheet and a fixing device D which fixes the toner image to the sheet.

The image transfer portion C includes a cartridge 200 which is detachably attachable to an image forming apparatus body 100, a transfer roller 101, and a laser scanner unit 102. The cartridge 200 includes a photosensitive drum 201, a charging device 202, and a development device 203.

When a controller (not illustrated) issues a print signal, a supporting member which supports a feeding roller 2 located at a standby position rocks and the feeding roller 2 abuts on an uppermost sheet of stacked sheets. Then, the sheet S stacked on a sheet cassette 1 serving as the stacking portion is fed to the image transfer portion C by the rotation of the feeding roller 2.

On the other hand, a surface of the photosensitive drum 201 is charged by the charging device 202. Then, the laser scanner unit 102 emits a laser beam from a light source (not illustrated) provided therein and irradiates the photosensitive drum with the laser beam. Thereby, a latent image is formed on the surface of the photosensitive drum. The latent image is developed by the development device 203, and thus the toner image is formed on the photosensitive drum 201. The toner image formed on the photosensitive drum 201 is transferred by conveying rollers 103 and 104 onto the sheet S fed to a transfer nip portion which is formed between the photosensitive drum 201 and the transfer roller 101.

The sheet S onto which the toner image is transferred is sent to the fixing device D, and heated and pressed by a fixing nip portion formed by a heat roller 105 and a pressure roller 106 of the fixing device D, so that the toner image on the sheet S is fixed to the sheet. The sheet S passing through the fixing device D is conveyed by discharge rollers 107 and 108, and discharged onto a discharge tray 109.

<Sheet Feeding Apparatus>

Next, the sheet feeding apparatus B will be described. FIGS. 2A to 2D are diagrams describing the cross section of the sheet feeding apparatus according to the first embodiment, and FIG. 3 is a plan view. In the sheet feeding apparatus, a plurality of sheets S is stacked on the sheet cassette 1, and these sheets are separated one by one and fed to the image transfer portion C.

The feeding roller 2 is disposed on an upper portion of the sheet cassette 1. The feeding roller 2 serves as a sheet feeding portion which feeds the stacked sheets S, and rotates in an arrow direction of FIG. 2A according to a feeding operation to feed an uppermost sheet of the sheets stacked on the sheet cassette 1.

On the downstream side in a sheet feeding direction of the feeding roller 2, there is provided a return roller 4 as a rotating member which abuts on the fed sheet S and is rotatable in a direction to return the sheet (a direction opposite to the feeding direction). In addition, a separation member 3 is provided on a sheet feeding path for the sheet S fed by the feeding roller 2 to reach the return roller 4 (the downstream side of the feeding roller 2 and the upstream side of the return roller 4). In the separation member 3, a slope surface portion (slope portion) against which the sheet fed by the feeding roller 2 butts is formed. The slope surface portion is inclined such that the downstream side in the feeding direction becomes the upper side. When a plurality of sheets is fed by the feeding roller 2, the slope surface portion acts such that one uppermost sheet is separated and fed by resistance caused when these sheets push up the inclined slope surface portion.

In rear cases, the sheets are not separated one by one by the slope surface portion of the separation member 3. In that case, the sheets are conveyed onto the return roller 4 in a state where the sheets are overlapped as sheets S1 and S2 of FIG. 2B. The return roller 4 is disposed at a position where the fed sheet abuts thereon in a tangential direction, and in a state where the sheet is not nipped. Since the return roller 4 rotates in the direction to return the fed sheet, the lowermost sheet S2 of the overlapped sheets is returned, and only the one uppermost sheet S1 is separated and fed to the image transfer portion C.

(Movement Configuration of Separation Member)

The separation member 3 is provided to be rotatable about a shaft 3a, and is movable between a separation position at which the fed sheet is separated by the rotation and a retraction position moved in a direction to be separated farther from the fed sheet than the separation position.

A movement mechanism (a changing unit) which moves the separation member 3 is configured by an actuator in the present embodiment. For example, the movement mechanism is configured such that a solenoid (a driving source) is connected to the separation member 3, and that the separation member 3 rotates between the separation position and the retraction position by turning on/off a driving force of the solenoid. In other words, the movement mechanism changes a protruding state of the return roller toward the sheet feeding path by moving the separation member 3.

As illustrated in FIG. 4, the actuator is operated by a controller 21 which turns on/off a solenoid 22 based on a detection result of, for example, a photo sensor 20 configuring a sheet detector which detects the fed sheet. The sheet detector according to the present embodiment includes a sensor lever 5 which rotates by the fed sheet and a sensor such as a photo sensor which detects the rotation of the lever 5. The sensor lever 5 is disposed on the downstream side of a contact position between the fed sheet and the return roller 4 in the sheet feeding direction. As illustrated in FIG. 2C, a leading end of the sheet fed by the feeding roller 2 pushes the sensor lever 5, and thus the sensor lever rotates. The sensor detects the rotation and thus the sheet is detected. Note that the configuration of the sheet detector is not limited to the above-described configuration, and may be, for example, a configuration of mechanically detecting the rotation of the sensor lever 5, or a configuration of detecting the presence or absence of the sheet using a photo sensor.

The separation member 3 is at the separation position until the sheet detector detects the sheet. When the sheet detector detects the sheet, the actuator is operated accordingly and the separation member moves to the retraction position. Therefore, the separation member 3 moves from the separation position to the retraction position after the leading end of the sheet fed by the feeding roller 2 reaches the return roller 4.

When the separation member 3 is at the separation position, as illustrated in FIG. 2B, the separation member is at a position with an angle suitable for separating the sheet fed by the slope surface portion. On the other hand, when the separation member 3 is at the retraction position, as illustrated in FIG. 2C, the separation member rotates in an arrow 7a direction to be at a position moved in a direction to be separated farther from the fed sheet than the separation position. Then, when the separation member 3 moves to the retraction position, the sheet S2 which is fed while being supported by the separation member 3 is not supported any more. Therefore, the separation member is pressed to the return roller 4 by the rigidity (stiffness) of the sheet. In other words, when the separation member 3 is located at the retraction position, a contact pressure of the sheet on the return roller 4 becomes high compared to a case where the separation member is located at the separation position and a return force by the return roller 4 also acts significantly. In other words, a protruding amount (a second protruding amount) of the return roller 4 toward the sheet feeding path at the time when the separation member 3 is located at the separation position is smaller than a protruding amount (a first protruding amount) of the return roller 4 toward the sheet feeding path at the time when the separation member is located at the retraction position. Note that, when the separation member is located at the retraction position, the return roller 4 may not necessarily protrude toward the sheet feeding path. On the other hand, when the separation member 3 is located at the separation position, the return roller 4 protrudes toward the sheet feeding path from the slope surface portion in order to separate the sheet.

Surfaces of the feeding roller 2 and the return roller 4 are made of a rubber material having a relatively high frictional resistance. Therefore, a frictional force between the sheet S1 and the feeding roller 2 and a frictional force between the sheet S2 and the return roller 4 become larger than a frictional force between the uppermost sheet S1 and the lower sheet S2 overlapped therewith. For this reason, the sheet S1 overcomes the frictional force between the sheets and is conveyed to the conveying roller 103 without formation of the nip, and the sheet S2 is returned to the upstream side in a conveyance direction.

When the sheet S1 is conveyed to the conveying roller 103, the driving of the feeding roller 2 is cut off. Then, the feeding roller 2 is rotatably driven only during the feed roller is in contact with the sheet S1. When the sheet S1 is conveyed and the feeding roller comes in contact with the sheet S2, the rotation of the feeding roller 2 is stopped. When the sheet S1 is further conveyed, a rear end of the sheet S1 passes through the sensor lever 5, and the sensor lever 5 reach a state illustrated in FIG. 2D, the actuator is operated according to a signal of a sensor detecting the above event, and rotates the separation member 3 in an arrow 7b direction of FIG. 2D. Thereby, the separation member 3 returns to the separation position. Therefore, the separation member 3 moves from the retraction position to the separation position after the rear end of the sheet fed by the feeding roller 2 passes through the return roller 4.

As described above, since the separation member 3 is made movable between the separation position at which the fed sheet is separated and the retraction position at which the sheet reliably abuts on the return roller 4, the sheets can reliably be separated by the separation member 3 and the return roller 4 one by one. In addition, it is possible to prevent the folding of the leading end of the fed sheet without strict position accuracy of the return roller 4 as in the related art.

<Another Example>

The above description has been made about the example in which the timing of moving the separation member 3 between the separation position and the retraction position is determined based on the detection of the sheet by the sheet detector. However, the actuator may be operated after a predetermined time elapses from the sheet feeding start by the feeding roller 2. Specifically, the actuator is operated after a time taken for the leading end of the sheet to pass through the contact position with the return roller 4 elapses from the sheet feeding start, and the separation member 3 is moved to the retraction position. In addition, the actuator is operated after a time taken for the rear end of the sheet to pass through the return roller 4 elapses from the sheet feeding start, and the separation member 3 is returned to the separation position. In this manner, it is possible to omit components such as a sheet detecting sensor.

In addition, in the above-described embodiment, the actuator is used as the movement mechanism which moves the separation member 3, but the separation member 3 may be moved between the separation position and the retraction position using a cam mechanism which operates in conjunction with the driving timing of the feeding roller 2. For example, as illustrated in FIG. 5A, a cam 8 having two cam surfaces different in a turning radius is provided to rotate in conjunction with the rotation of the feeding roller 2. A cam contact portion 3b provided in the separation member 3 is caused to abut on the cam surfaces, and applies a force to the cam surfaces by a spring 9.

In the case of the cam mechanism described above, the cam 8 rotates in conjunction with the feeding roller 2. As illustrated in FIG. 5A, when the cam contact portion 3b abuts on a cam surface having a small radius, the separation member 3 moves to the separation position. On the other hand, as illustrated in FIG. 5B, when the cam contact portion 3b abuts on a cam surface having a large radius, the separation member 3 moves to the retraction position. Thereby, when the feeding roller 2 feeds the sheet to the slope surface portion of the separation member 3, it is possible to move the separation member to the separation position, and immediately after the leading end of the sheet passes through the contact portion with respect to the return roller 4, it is possible to move the separation member to the retraction position. In this manner, as described above, the sheet detecting sensor is not necessary, and there is no need to manage the sheet feeding time.

In addition, the above description has been made about the configuration in which the movement mechanism moves the separation member 3 with respect to the return roller 4 to change the protruding amount of the return roller 4 toward the sheet feeding path. However, the present invention may have a configuration of moving the return roller 4 with respect to the separation member 3.

Second Embodiment

Next, an apparatus according to a second embodiment will be described with reference to FIGS. 6A and 6B. Note that, since the basic configurations of the apparatus in the present embodiment are same as those of the above-described embodiment, the redundant descriptions will be omitted, and the members having the same functions as those of the above-described embodiment will be denoted by the same reference numerals.

A surface of a return roller 4 is made of a rubber material having a relatively high frictional resistance. For this reason, when a leading end of a sheet fed by a feeding roller 2 butts against the return roller 4 rotating in a direction to return the sheet, there is a possibility that the folding of the leading end of the sheet, and the like occur (see FIG. 9D).

Thus, in the present embodiment, there is provided a rotation switching mechanism which switches a rotation direction of the return roller 4. Then, the return roller 4 is rotated in a direction to feed the sheet at the time of the sheet feeding start by the feeding roller 2, and is rotated in the direction to return the sheet after the leading end of the fed sheet passes through the return roller 4.

Specifically, as illustrated in FIG. 6A, the return roller 4 is rotated simultaneously with the driving start of the feeding roller 2. The rotation direction of the return roller 4 at this time is the direction to feed the sheet. Even though the leading end of the fed sheet abuts on the return roller 4, since the return roller 4 rotates in the direction to feed the sheet as described above, the leading end of the sheet passes through the return roller 4 without being folded. Then, when the fed sheet pushes up a sensor lever 5, the controller switches the rotation direction of the return roller 4 to the reverse direction based on a signal from a sensor detecting the above event. Thereby, as illustrated in FIG. 6B, even when sheets are overlapped without being separated by a slope surface portion of a separation member 3, an uppermost sheet S1 is fed as is, but a lower sheet S2 is returned by the return roller 4 and separated from the sheet S1.

When the separated sheet S1 is conveyed to a conveying roller 103, a driving force of the feeding roller 2 is cut off. During the feeding roller 2 abuts on the sheet S1, the feeding roller is driven by the sheet S1, and the sheet S1 is further conveyed. When the sheet S1 goes through the feeding roller 2, the feeding roller 2 is stopped.

When the sheet S1 is further conveyed, a rear end of the sheet S1 passes through the sensor lever 5, and the sensor lever 5 returns to a position of FIG. 6A, a controller stops a motor which drives the return roller 4, based on a signal from a sensor detecting the above event.

As described above, when the leading end of the fed sheet abuts on the return roller 4, the return roller 4 is rotated in the sheet feeding direction, so that it is possible to reliably prevent the folding of the leading end of the sheet. Then, immediately after the leading end of the sheet passes through the return roller 4, the return roller 4 is rotated in the reverse direction (rotated in the direction to return the sheet), so that it is possible to reliably separate the overlapped sheets.

In the present embodiment, it is possible to separate the sheets while preventing the folding of the leading end of the sheet without providing a movement mechanism which moves the separation member 3 between a separation position and a retraction position according to a sheet feeding state as described in the first embodiment. However, in a case where the movement mechanism is provided to switch the rotation direction of the return roller 4 according to the sheet feeding state, and to move the separation member 3 between the separation position and the retraction position, it is possible to separate the sheets while further reliably preventing the folding of the leading end of the sheet.

<Another Example>

The above description has been made about the example in which the timing of switching the rotation direction of the return roller 4 is determined based on the sheet detection by the sheet detector, but the timing of reversing or stopping the return roller may be determined based on the driving time of the feeding roller 2 in a similar manner to the first embodiment described above. In other words, the rotation direction of the return roller 4 may be switched from the direction to feed the sheet to the direction to return the sheet after a predetermined time elapses from the sheet feeding start by the feeding roller 2. In this manner, it is possible to omit components such as a sheet detecting sensor.

In addition, the return roller 4 may be provided to be movable between the separation position to abut on the fed sheet and the retraction position to be separated from the fed sheet. Thereby, when the return roller 4 rotates in the direction to feed the sheet, the return roller moves to the retraction position in order not to abut on the sheet, and when the return roller rotates in the direction to return the sheet, the return roller moves to the separation position in order to reliably abut on the sheet.

For example, as illustrated in FIGS. 7A and 7B, a rotation shaft 4a of the return roller 4 is attached to be movable along a long hole 10. Then, as illustrated in FIGS. 8A to 8C, a roller gear 11 fixed to an end in the longitudinal direction of the return roller 4 is caused to engage with a driving transmission gear 12.

In the above-described configuration, as illustrated in FIG. 8A, when the driving transmission gear 12 is rotated in the counterclockwise direction in order to rotate the return roller 4 in the sheet feeding direction, a force is applied to the roller gear 11 in an arrow 13a direction by a driving resistance. For this reason, the rotation shaft 4a of the return roller 4 moves to a position (the retraction position) to abut on a right end of the long hole 10. Thereby, the leading end of the fed sheet does not abut on the return roller 4.

On the other hand, as illustrated in FIG. 8B, when the driving transmission gear 12 is rotated in the clockwise direction in order to rotate the return roller 4 in the direction to return the sheet, a force is applied to the roller gear 11 in an arrow 13b direction by the driving resistance. For this reason, the rotation shaft 4a of the return roller 4 moves to a position (the separation position) to abut on a left end of the long hole 10. Thereby, the sheet reliably abuts on the return roller 4, and the overlapped sheet S2 is reliably returned by the rotation of the return roller 4.

Note that, in a case where the overlapped sheet is separated by the return roller 4, a suitable return force by the return roller 4 is different according to a type of the sheet (difference in basis weight, stiffness, material, etc.). Thus, the protruding amount toward the sheet feeding path when the return roller 4 is at the separation position may be made adjustable. For example, as illustrated in FIG. 8C, a rocking stopper 14 which is rockable about a shaft 14a and fixable at a rocking position is attached to be caught in the long hole 10. Thereby, by fixing the rocking stopper 14 while changing its angle, the rotation shaft 4a of the return roller 4 can change a moving range of the long hole 10, and the separation position can be set in any of a plurality of places. Therefore, the separation position can be changed according to the type of the sheet, and a protruding amount toward the sheet feeding path when the return roller 4 is at the separation position can be adjusted to be an optimal value.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No. 2014-015447, filed Jan. 30, 2014, which is hereby incorporated by reference herein in its entirety.

Claims

1. A sheet feeding apparatus comprising: a stacking portion on which a sheet is stacked;a sheet feeding portion configured to feed the sheet stacked on the stacking portion;a rotating member provided on a downstream of the stacking portion in a feeding direction of the sheet and configured to rotate in a direction opposite to the feeding direction;a slope portion of which at least a part is provided on the downstream of the stacking portion in the feeding direction and on an upstream of the rotating member, and which is inclining so that the downstream side in the feeding direction becomes higher; anda changing unit configured to change a protruding amount of the rotating member toward a sheet feeding path of the sheet.

2. The sheet feeding apparatus according to claim 1, wherein the rotating member protrudes from the slope portion toward the sheet feeding path.

3. The sheet feeding apparatus according to claim 1, wherein the changing unit changes the protruding amount of the rotating member toward the sheet feeding path between a first protruding amount and a second protruding amount, andwherein the second protruding amount is larger than the first protruding amount.

4. The sheet feeding apparatus according to claim 1, wherein the changing unit changes a protruding state of the rotating member toward the sheet feeding path between a state where the rotating member does not protrude toward the sheet feeding path and a state where the rotating member protrudes toward the sheet feeding path.

5. The sheet feeding apparatus according to claim 1, wherein sheets fed by the sheet feeding portion are separated by the slope portion one by one.

6. The sheet feeding apparatus according to claim 3, wherein the changing unit changes, after a leading end of the sheet fed by the sheet feeding portion reaches the rotating member, the protruding amount of the rotating member toward the sheet feeding path from the first protruding amount to the second protruding amount which is larger than the first protruding amount.

7. The sheet feeding apparatus according to claim 6, wherein the changing unit changes, after a rear end of the sheet fed by the sheet feeding portion passes through the rotating member, the protruding amount of the rotating member toward the sheet feeding path from the second protruding amount to the first protruding amount.

8. The sheet feeding apparatus according to claim 1, wherein the changing unit changes a contact pressure of the rotating member on the sheet fed by the sheet feeding portion.

9. The sheet feeding apparatus according to claim 1, further comprising: a sheet detector configured to detect the sheet fed by the sheet feeding portion,wherein the changing unit changes the protruding amount of the rotating member toward the sheet feeding path based on a detection result of the sheet detector.

10. The sheet feeding apparatus according to claim 1, wherein the changing unit changes the protruding amount of the rotating member toward the sheet feeding path after a predetermined time elapses from a time when the sheet feeding portion starts a feeding operation of the sheet.

11. The sheet feeding apparatus according to claim 1, wherein the changing unit is a movement mechanism which moves the slope portion.

12. The sheet feeding apparatus according to claim 11, wherein the movement mechanism includes a cam mechanism which rotates in conjunction with driving of the sheet feeding portion.

13. The sheet feeding apparatus according to claim 11, wherein the movement mechanism includes a driving source configured to generate a driving force and an actuator which is operated by the driving force.

14. A sheet feeding apparatus comprising: a stacking portion on which a sheet is stacked;a sheet feeding portion configured to feed the sheet stacked on the stacking portion;a rotating member provided on a downstream of the stacking portion in a feeding direction of the sheet and is rotatable in the feeding direction and in a direction opposite to the feeding direction;a slope portion of which at least a part is provided on the downstream of the stacking portion in the feeding direction and on an upstream of the rotating member, and which is inclining so that the downstream side in the feeding direction becomes higher; anda rotation switching mechanism configured to switch a rotation direction of the rotating member, and rotates the rotating member in the opposite direction after a leading end of the sheet fed by the sheet feeding portion passes through the rotating member.

15. The sheet feeding apparatus according to claim 14, further comprising: a sheet detector configured to detect the sheet fed by the sheet feeding portion,wherein the rotation switching mechanism switches the rotation direction of the rotating member based on a detection result of the sheet detector.

16. The sheet feeding apparatus according to claim 14, wherein the rotation switching mechanism switches the rotation direction of the rotating member from a direction to feed the sheet to a direction to return the sheet after a predetermined time elapses from a time when the sheet feeding portion starts to feed the sheet.

17. The sheet feeding apparatus according to claim 14, wherein the rotating member is provided to be movable between a separation position to abut on the fed sheet and a retraction position to be separated from the sheet, moves to the retraction position when the rotating member rotates in the direction to feed the sheet, and moves to the separation position when the rotating member rotates in the direction to return the sheet.

18. The sheet feeding apparatus according to claim 17, wherein the separation position is settable in any one of a plurality of places.

19. The sheet feeding apparatus according to claim 14, further comprising: a movement mechanism configured to move the rotating member between a separation position at which the fed sheet is separated and a retraction position moved in a direction to be separated farther from the fed sheet than the separation position.

20. The sheet feeding apparatus according to claim 19, wherein the movement mechanism moves the rotating member to the retraction position when the rotating member rotates in the direction to feed the sheet, and moves the rotating member to the separation position when the rotating member rotates in the direction to return the sheet.

21. An image forming apparatus comprising: the sheet feeding apparatus according to claim 1; andan image forming portion which forms an image on a fed sheet.

22. An image forming apparatus comprising: the sheet feeding apparatus according to claim 14; andan image forming portion which forms an image on a fed sheet.