Sheet feeding apparatus and image forming apparatus

Abstract

A sheet feeding apparatus includes a stacking portion, a rotary feeding member configured to feed the sheet in a sheet feeding direction, a first separation portion including a separation surface, the detachable unit including a second separation portion. A direction that intersects both the sheet feeding direction and a rotation-axis direction of the rotary feeding member, and that extends from the separation surface toward the rotary feeding member is defined as a projection direction. The second separation portion is positioned downstream of the separation surface in the projection direction in a state where the detachable unit is attached to the first separation portion. Another portion of the detachable unit other than the second separation portion is positioned upstream of the separation surface in the projection direction in a state where the detachable unit is attached to the first separation portion.

Description

BACKGROUNDField of the Technology

[0001] The present disclosure relates to a sheet feeding apparatus that feeds sheets, and an image forming apparatus that includes the sheet feeding apparatus.Description of the Related Art

[0002] Japanese Patent Application Publication No. 2022-001517 proposes a sheet feeding apparatus that includes a sloped member including a sloped surface, and a separation-piece unit detachably attached to the sloped member. The separation-piece unit includes a plurality of separation pieces, and a support portion that supports the plurality of separation pieces. The support portion includes a top surface formed so as to be flush with the sloped surface in a state where the separation-piece unit is attached to the sloped member. A sheet fed by a feeding roller slides on the sloped surface of the sloped member, and the top surface of the support portion and the plurality of separation pieces of the separation-piece unit, so that the sheet is separated from other sheets, one by one.

[0003] The plurality of separation pieces described in Japanese Patent Application Publication No. 2022-001517 is formed so as to project more than the sloped surface of the sloped member and the top surface of the support portion that supports the separation pieces do. Thus, the plurality of separation pieces may wear earlier than the sloped surface of the sloped member and the top surface of the support portion do (each of the sloped surface of the sloped member and the top surface of the support portion serves as a separation surface). The separation-piece unit is a unit in which the support portion and the plurality of separation pieces are formed integrally with each other. Thus, in a case where one separation-piece unit is replaced with another, the top surface of the support portion that has not yet worn is also replaced with another by the replacement of the one separation-piece unit.SUMMARY

[0004] According to a first aspect of the disclosure, a sheet feeding apparatus includes a stacking portion on which a sheet is stacked, a rotary feeding member configured to feed the sheet stacked on the stacking portion, toward an image forming portion in a sheet feeding direction, a first separation portion including a separation surface disposed so as to contact the sheet fed by the rotary feeding member, and a detachable unit detachably attached to the first separation portion, the detachable unit including a second separation portion that contacts a sheet fed by the rotary feeding member so as to separate the sheet, together with the separation surface, one by one. A direction that intersects both the sheet feeding direction and a rotation-axis direction of the rotary feeding member, and that extends from the separation surface toward the rotary feeding member is defined as a projection direction. The second separation portion is positioned downstream of the separation surface in the projection direction in a state where the detachable unit is attached to the first separation portion. Another portion of the detachable unit other than the second separation portion is positioned upstream of the separation surface in the projection direction in a state where the detachable unit is attached to the first separation portion.

[0005] According to a second aspect of the disclosure, a sheet feeding apparatus includes a stacking portion on which a sheet is stacked, a rotary feeding member configured to feed the sheet stacked on the stacking portion, toward an image forming portion in a sheet feeding direction, a first separation portion including a separation surface disposed so as to contact the sheet fed by the rotary feeding member, and a detachable unit detachably attached to the first separation portion, the detachable unit including a second separation portion that contacts a sheet fed by the rotary feeding member so as to separate the sheet, together with the separation surface, one by one. A direction that intersects both the sheet feeding direction and a rotation-axis direction of the rotary feeding member, and that extends from the separation surface toward the rotary feeding member is defined as a projection direction. The second separation portion is positioned downstream of the separation surface in the projection direction in a state where the detachable unit is attached to the first separation portion. Another portion of the detachable unit other than the second separation portion is configured not to contact the sheet fed by the rotary feeding member in a state where the detachable unit is attached to the first separation portion.

[0006] Features of the present disclosure will become apparent from the following description of embodiments with reference to the attached drawings. The following description of embodiments is described by way of example.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is an overall schematic diagram illustrating an image forming apparatus of a first embodiment.

[0008] FIG. 2A is a perspective view illustrating a sheet feeding apparatus in a state where a cassette is attached to an apparatus body.

[0009] FIG. 2B is a perspective view illustrating the cassette detached from the apparatus body and a configuration of surroundings of the cassette.

[0010] FIG. 3A is a perspective view illustrating a sheet separation unit attached to a separation wall.

[0011] FIG. 3B is a perspective view illustrating a state where the sheet separation unit is being detached from the separation wall.

[0012] FIG. 3C is a perspective view illustrating a state where the sheet separation unit has been detached from the separation wall.

[0013] FIG. 4 is a perspective view illustrating a state where a portion of the sheet separation unit attached to the separation wall is cut off.

[0014] FIG. 5A is a perspective view illustrating a sheet separation unit of a second embodiment.

[0015] FIG. 5B is a perspective view illustrating the sheet separation unit detached from a separation wall.

[0016] FIG. 6 is a perspective view illustrating a state where a portion of the sheet separation unit attached to the separation wall is cut off.

[0017] FIG. 7A is a perspective view illustrating a state where a locking member and a sheet separation unit of a third embodiment are assembled to a separation wall.

[0018] FIG. 7B is a perspective view illustrating a state where the locking member and the sheet separation unit are detached from the separation wall.

[0019] FIG. 8A is a perspective view illustrating a state where a cover of a fourth embodiment is positioned at a closed position.

[0020] FIG. 8B is a perspective view illustrating a state where the cover is positioned at an open position.

[0021] FIG. 8C is a perspective view illustrating a state where a sheet separation unit is detached from a separation wall.

[0022] FIG. 9A is a perspective view illustrating a state where a cover of a fifth embodiment is positioned at a closed position.

[0023] FIG. 9B is a perspective view illustrating a state where the cover is positioned at an open position.

[0024] FIG. 9C is a perspective view illustrating a state where a sheet separation unit is detached from a separation wall.

[0025] FIG. 10 is a perspective view illustrating a state where a portion of the sheet separation unit attached to the separation wall and of the cover are cut off.

[0026] FIG. 11A is a perspective view illustrating a modification of the fifth embodiment in a case where the separation wall and the sheet separation unit are disposed in the apparatus body.

[0027] FIG. 11B is a perspective view illustrating the modification of the fifth embodiment in a state where the cassette is drawn in a direction indicated by an arrow B.

[0028] FIG. 12A is a perspective view illustrating a state where a cover of a sixth embodiment is positioned at a closed position.

[0029] FIG. 12B is a perspective view illustrating a state where the cover is positioned at an open position.

[0030] FIG. 12C is a perspective view illustrating a state where a sheet separation unit is detached from a separation wall.

[0031] FIG. 13 is a diagram illustrating one example of an image forming apparatus that has the configuration of the sixth embodiment.

[0032] FIG. 14A is a diagram illustrating a positional relationship between a sheet separation portion, a separation slope, and a sloped surface of the first embodiment.

[0033] FIG. 14B is a diagram illustrating a state where a sheet is separated from other sheets, one by one, by the sheet separation portion and the separation slope.DESCRIPTION OF THE EMBODIMENTSFirst EmbodimentOverall Configuration

[0034] First, a first embodiment of the present disclosure will be described. An image forming apparatus 1 is an electrophotographic laser-beam printer. As illustrated in FIG. 1, the image forming apparatus 1 includes an image forming portion 80 that forms an image on a sheet S, a sheet feeding apparatus 90, and a fixing apparatus 31. Note that examples of the image forming apparatus include a printer, a copying machine, a facsimile, and a multifunction printer, and that the image forming apparatus forms an image on a sheet, used as a recording medium, in accordance with image information sent from an external PC or read from a document. In addition, there is a case where an accompanying apparatus, such as an option feeder, an image reading apparatus, or a sheet processing apparatus, is attached to the body of the image forming apparatus that has the image forming function. In this case, the whole system in which the accompanying apparatus is attached to the body of the image forming apparatus is also a type of the image forming apparatus.

[0035] The image forming portion 80 includes four process cartridges PY, PM, PC, and PK, and a scanner 21. The four process cartridges respectively form four-color toner images of yellow (Y), magenta (M), cyan (C), and black (K).

[0036] Note that the four process cartridges PY, PM, PC, and PK have the same configuration except that they produce different colors of image. For this reason, the configuration and the image forming process of only the process cartridge PY will be described, and the description for the process cartridges PM, PC, and PK will be omitted.

[0037] The process cartridge PY includes a photosensitive drum 22, a charging roller (not illustrated), and a developing roller 23. The photosensitive drum 22 has an organic photoconductive layer coated on the outer surface of an aluminum cylinder, and is rotated by a driving motor (not illustrated). In addition, the image forming portion 80 includes an intermediate transfer belt 25 wound around a driving roller 25a and a tension roller 25b, and primary transfer rollers 24Y, 24M, 24C, and 24K disposed inside the intermediate transfer belt 25.

[0038] The fixing apparatus 31 includes a fixing roller 31a that is heated by a heater (not illustrated), and a pressing roller 31b that is in pressure contact with the fixing roller 31a. The sheet feeding apparatus 90 is disposed in a lower portion of the image forming apparatus 1; and includes a cassette 11 that supports the sheet S, and a pickup roller 12 that serves as a rotary feeding member that feeds the sheet S. Examples of the sheet S may include a paper sheet, such as a sheet for any purpose or an envelope, a plastic film such as an overhead projector (OHP) sheet, and a cloth sheet. In addition, instead of the pickup roller 12, a feeding belt may be used. For example, the feeding belt may convey the sheet while sucking the sheet by using air.

[0039] Next, an image forming operation of the image forming apparatus 1 configured in this manner will be described. If the scanner 21 receives an image signal from an apparatus, such as a personal computer (not illustrated), the scanner 21 emits a laser beam, produced in accordance with the image signal, to the photosensitive drum 22 of the process cartridge PY.

[0040] Since the surface of the photosensitive drum 22 is uniformly charged in advance by the charging roller so as to have a predetermined polarity and potential, an electrostatic latent image is formed on the surface of the photosensitive drum 22 if the surface is irradiated with the laser beam from the scanner 21. The electrostatic latent image formed on the photosensitive drum 22 is developed by the developing roller 23, so that a toner image of yellow (Y) is formed on the photosensitive drum 22.

[0041] Similarly, the photosensitive drums of the process cartridges PM, PC, and PK are also irradiated with laser beams from the scanner 21, so that toner images of magenta (M), cyan (C), and black (K) are formed on the respective photosensitive drums. The toner images formed on the respective photosensitive drums and having respective colors are transferred onto the intermediate transfer belt 25 by the primary transfer rollers 24Y, 24M, 24C, and 24K; and conveyed to a secondary transfer roller 26 by the intermediate transfer belt 25, which is rotated by the driving roller 25a. Note that an image forming process for one color is performed at a timing at which a corresponding toner image is superposed on an upstream toner image which has been primary-transferred onto the intermediate transfer belt 25.

[0042] In parallel with the image forming process, the sheet S stored in the cassette 11 of the sheet feeding apparatus 90 is fed by the pickup roller 12, and conveyed to a registration roller pair 15 via a conveyance guide 10 and a conveyance roller pair 14. The skew of the sheet S is corrected by the registration roller pair 15, and the sheet S is then conveyed at a predetermined conveyance timing. Then, a full-color toner image on the intermediate transfer belt 25 is transferred onto the sheet S by a secondary transfer bias applied to the secondary transfer roller 26.

[0043] The sheet S to which the toner image has been transferred is then applied with predetermined heat and pressure by the fixing roller 31a and the pressing roller 31b of the fixing apparatus 31, so that the toner is melted and solidified (fixed). The sheet S that has passed through the fixing apparatus 31 is discharged to a discharging tray 34 by a discharge roller pair 32.Sheet Feeding Apparatus

[0044] Next, the sheet feeding apparatus 90 will be described with reference to FIGS. 2A to 4. FIG. 2A is a perspective view illustrating the sheet feeding apparatus 90 in a state where the cassette 11 is attached to an apparatus body 1A. FIG. 2B is a perspective view illustrating the cassette 11 detached from the apparatus body 1A and a configuration of surroundings of the cassette 11. FIG. 3A is a perspective view illustrating a sheet separation unit 62 attached to a separation wall 60. FIG. 3B is a perspective view illustrating a state where the sheet separation unit 62 is being detached from the separation wall 60. FIG. 3C is a perspective view illustrating a state where the sheet separation unit 62 has been detached from the separation wall 60. FIG. 4 is a perspective view illustrating a state where a portion of the sheet separation unit 62 attached to the separation wall 60 is cut off.

[0045] As illustrated in FIGS. 1 and 2A, the cassette 11 of the sheet feeding apparatus 90 is attached to the apparatus body 1A of the image forming apparatus 1 such that the cassette 11 can be drawn from the apparatus body 1A. The cassette 11 of the present embodiment can be drawn toward the front of the sheet in FIG. 1. The cassette 11 that serves as a drawing unit includes a cassette frame 9, a tray 50, the separation wall 60, and the sheet separation unit 62. The tray 50 serves as a stacking portion on which the sheet S is stacked.

[0046] As illustrated in FIG. 2A, the apparatus body 1A includes a roller rotation shaft 12s that is rotatably supported. In addition, a pickup arm 12a is pivotally supported by the roller rotation shaft 12s. The pickup arm 12a rotatably supports the pickup roller 12. In addition, the apparatus body 1A includes a roller driving shaft 44 that is driven and rotated by a motor M1. A gear 45 is fixed to the roller driving shaft 44, and in a state where the cassette 11 is attached to the apparatus body 1A, the rotation of the gear 45 is transmitted to the pickup roller 12 via an idler gear train 43, the roller rotation shaft 12s, and a pickup gear train 42.

[0047] In addition, a lift input shaft 54 is rotatably supported by one end portion of the cassette frame 9. In a state where the cassette 11 is attached to the apparatus body 1A, the lift input shaft 54 is driven and rotated by a lift motor M2 disposed in the apparatus body 1A. In addition, a lift input gear 53 is fixed to the lift input shaft 54, and meshes with a fan-shaped lift gear 51. The lift gear 51 rotates together with a lift plate 51a disposed below the tray 50. The tray 50 is pushed upward by the lift plate 51a by the rotation of the lift plate 51a driven by the lift motor M2, and pivots upward around a pivot shaft 50a. With this operation, the sheet S stacked on the tray 50 is lifted to a position at which the sheet S can be fed by the pickup roller 12.

[0048] Next, with reference to FIGS. 2B to 4, a configuration of components of the sheet feeding apparatus 90 in the vicinity of the separation wall 60 will be described. Note that FIG. 4 is a perspective view for describing the configuration of components in the vicinity of the separation wall 60. In FIG. 4, a portion of an upper portion of the separation wall 60 illustrated in FIG. 3A is cut off, and the remaining portion of the separation wall 60 is viewed from a side opposite to the side from which the separation wall 60 illustrated in FIG. 3A is viewed.

[0049] As illustrated in FIGS. 2B and 3A, the cassette frame 9 of the cassette 11 holds the separation wall 60. The separation wall 60 that serves as a first separation portion includes a separation slope 60a that serves as a separation surface disposed so as to be able to contact the sheet S fed by the pickup roller 12. The separation slope 60a includes a first slope 30L and a second slope 30R that are disposed side by side with each other in a below-described width direction W, as illustrated in FIG. 3C. In the separation wall 60, an opening portion 66 is formed between the first slope 30L and the second slope 30R. The opening portion 66 is opened toward a direction perpendicular to the separation slope 60a, that is, toward the downstream side in a below-described projection direction PD. The sheet separation unit 62 described below is inserted into the opening portion 66. Note that the separation wall 60 may not be a single member. For example, the separation wall 60 may be constituted by a first member that includes the first slope 30L and a second member that includes the second slope 30R. In another case, the separation wall may include another member other than the first member and the second member.

[0050] A pair of holding members 65L and 65R is attached to the opening portion 66. In the following description, as illustrated in FIGS. 2A and 2B, a width direction of the sheet S orthogonal to a sheet feeding direction FD, which is a direction in which the pickup roller 12 feeds the sheet S, is referred to as the width direction W. In other words, the width direction W intersects the sheet feeding direction FD. In addition, the width direction W is a direction parallel to the rotation axis of the pickup roller 12, that is, is a rotation-axis direction of the pickup roller 12. Of a pair of members disposed side by side in the width direction W, a member on the left side in the view of the separation slope 60a is given a symbol “L”, and a member on the right side is given a symbol “R”. Since the members of the pair have the same configuration, only one of the members will be described, and the description of the other will be omitted as appropriate.

[0051] Each of the holding members 65L and 65R has a sheet contact surface 65a. The sheet contact surface 65a is positioned upstream of the separation slope 60a in the projection direction PD. The projection direction PD intersects both the sheet feeding direction FD and the width direction W, and extends from the separation slope 60a toward the pickup roller 12. In other words, the sheet contact surface 65a is positioned at a position that is separated more from a feeding path 17 (see FIG. 1) in the projection direction PD than the separation slope 60a is. The feeding path 17 serves as a conveyance path through which the sheet S fed by the pickup roller 12 passes. That is, the sheet contact surface 65a is positioned at a position retracted upstream of the separation slope 60a in the projection direction PD. Thus, the sheet contact surface 65a hardly prevents the sheet S from contacting the separation slope 60a.

[0052] The holding members 65L and 65R that serve as a restricting member are supported by the separation wall 60 such that the holding members 65L and 65R can move in the width direction W. Specifically, the holding members 65L and 65R can slide between a holding position illustrated in FIG. 3A and a separation position illustrated in FIGS. 3B and 3C. At the holding position, the holding members 65L and 65R hold the sheet separation unit 62 for restricting the sheet separation unit 62 inserted in the opening portion 66, from being detached from the separation wall 60. The holding members 65L and 65R move to the separation position illustrated in FIGS. 3B and 3C, by the holding member 65L sliding in a direction indicated by an arrow A1 and the holding member 65R sliding in a direction indicated by an arrow A2. The direction indicated by the arrow A1 is a direction which is parallel to the width direction W, and in which the holding member 65L is separated from the holding member 65R. The direction indicated by the arrow A2 is a direction which is parallel to the width direction W, and in which the holding member 65R is separated from the holding member 65L. The holding position that serves as a restricting position is a position closer to a center portion of the separation wall 60 in the width direction W. The separation position that serves as an allowable position is a position separated more from the center portion of the separation wall 60 in the width direction W, than the holding position is. That is, the holding members 65L and 65R move from the holding position toward the separation position in a direction in which the holding members 65L and 65R are separated from each other.

[0053] The holding members 65L and 65R cover a part of the opening portion 66 at the holding position, and increases the opening area of the opening portion 66 by moving from the holding position to the separation position. Thus, at the separation position, the holding members 65L and 65R release the sheet separation unit 62, and allow the sheet separation unit 62 to be detached from the separation wall 60.

[0054] The sheet separation unit 62 includes a pair of sheet separation portions 63L and 63R that are detachably attached to the separation wall 60, and that, together with the separation slope 60a, separate the sheet S, one by one, fed by the pickup roller 12, by contacting the sheet S. The sheet separation portions 63L and 63R are positioned downstream of the separation slope 60a in the projection direction PD. In other words, in a state where the sheet separation unit 62 is attached to the separation wall 60, the sheet separation portions 63L and 63R project more toward the feeding path 17 than the separation slope 60a does. Thus, the sheet separation portions 63L and 63R more easily abut against the sheet S that passes through the feeding path 17, than the separation slope 60a does.

[0055] Note that in the present embodiment, the pair of sheet separation portions 63L and 63R constitutes a sheet separation portion 63 that serves as a second separation portion. The sheet separation portion 63 may not be the pair of sheet separation portions 63L and 63R. For example, the sheet separation portion 63 may be constituted by a single sheet separation portion, or by three or more sheet separation portions. Preferably, one or more sheet separation portions are disposed symmetrically right and left, with respect to a center portion of the feeding path 17 in the width direction W.

[0056] In the present embodiment, as illustrated in FIG. 3C, the sheet separation unit 62 that serves as a detachable unit includes a first end FE and a second end SE formed in the width direction W. The sheet separation portion 63L that serves as a first sheet-separation portion is disposed at a position closer to the first end FE than to the second end SE. The sheet separation portion 63R that serves as a second sheet-separation portion is disposed at a position closer to the second end SE than to the first end FE. The sheet separation portions 63L and 63R are disposed symmetrically right and left, with respect to a center portion of the feeding path 17 in the width direction W.

[0057] Furthermore, the sheet separation unit 62 includes a sloped surface 62e disposed between the pair of sheet separation portions 63L and 63R in the width direction W. The sloped surface 62e is positioned at a position retracted upstream of the separation slope 60a in the projection direction PD. In other words, the amount of projection of the sloped surface 62e toward the feeding path 17 is smaller than the amount of projection of the separation slope 60a toward the feeding path 17. Thus, although the sloped surface 62e faces the feeding path 17, the sloped surface 62e does not abut against the sheet S that passes through the feeding path 17. In addition, in a state where the sheet separation unit 62 is attached to the separation wall 60, the portion of the sheet separation unit 62 other than the sheet separation portions 63L and 63R and including the sloped surface 62e does not contact the sheet S fed by the pickup roller 12. This is because in a state where the sheet separation unit 62 is attached to the separation wall 60, the portion of the sheet separation unit 62 other than the sheet separation portions 63L and 63R is positioned upstream of the separation slope 60a in the projection direction PD.

[0058] By the way, there is a case where a sheet, such as a thin paper sheet, that has a smaller stiffness (grammage) cannot be separated from other sheets, one by one, by only the separation slope 60a of the separation wall 60. Thus, for increasing the separation performance for the sheet S, each of the sheet separation portions 63L and 63R has a surface with projections and depressions, or is made of a material having a coefficient of friction larger than that of the separation slope 60a and the sheet contact surface 65a. As a result, the sheet S, such as a thin paper sheet, fed by the pickup roller 12, conveyed through the feeding path 17, and having a smaller stiffness is also separated from other sheets, one by one, if the sheet S contacts the sheet separation portions 63L and 63R in addition to the separation slope 60a.

[0059] Note that in the present embodiment, the sheet separation portions 63L and 63R are defined as a portion of the sheet separation unit 62 that projects more toward the feeding path 17 in the projection direction PD than the separation slope 60a does, in a state where the sheet separation unit 62 is attached to the separation wall 60. Preferably, at least a portion of the sheet separation portions 63L and 63R has a coefficient of friction larger than that of the separation slope 60a. For example, the separation slope 60a may be made of a resin material, and at least a portion of the sheet separation portions 63L and 63R may be made of a material, such as a rubber material, that has a coefficient of friction larger than that of the resin material. In this case, if only the portion of the sheet separation portions 63L and 63R made of the rubber material wears, only the portion of the sheet separation portions 63L and 63R may be replaced with another.

[0060] In the present embodiment, as illustrated in FIG. 3C, a width D1 of the opening portion 66 is longer, in the width direction W, than a distance D2 between the sheet separation portion 63L that serves as a first separation piece and the sheet separation portion 63R that serves as a second separation piece. Thus, since the opening portion 66 has a large opening area, the sheet separation unit 62 can be easily attached to the opening portion 66, so that the workability of replacement of the sheet separation unit 62 can be improved.

[0061] As illustrated in FIGS. 3B and 4, abutment portions 61L and 61R, and an urging member 64 are disposed in the vicinity of the opening portion 66 and on the back side of the separation slope 60a of the separation wall 60. The sheet separation unit 62 includes a pair of unit abutment surfaces 62aL and 62aR that serves as an abutted portion that can abut against the abutment portions 61L and 61R of the separation wall 60. The urging member 64 includes a compression coil spring 64a supported, for example, by the separation wall 60, and a plate member 64b that is fixed to the compression coil spring 64a and that can abut against the sheet separation unit 62.

[0062] The unit abutment surfaces 62aL and 62aR of the sheet separation unit 62 abut against the abutment portions 61L and 61R of the separation wall 60 in a state where the sheet separation unit 62 is inserted in the opening portion 66 and urged by the urging member 64. In this manner, the sheet separation unit 62 is positioned with respect to the separation wall 60. In other words, the urging member 64 urges the sheet separation unit 62 toward the feeding path 17 in the projection direction PD, in a state where the sheet separation unit 62 is attached to the separation wall 60. In this state, the unit abutment surfaces 62aL and 62aR are positioned upstream of the abutment portions 61L and 61R in the projection direction PD.

[0063] The surface of the sheet separation portions 63L and 63R wear due to sliding friction between the sheet separation portions 63L and 63R and the sheet S. If the wear of the sheet separation portions 63L and 63R increases, the uneven shape of the surface of the sheet separation portions 63L and 63R becomes flat, so that the resistance force for separation decreases, and the height of the sheet separation portions 63L and 63R decreases. As a result, the proper amount of projection of the sheet separation portions 63L and 63R with respect to the separation slope 60a cannot be kept, which causes the deterioration of the separation performance. For this reason, if many sheets S have been fed and the separation performance has deteriorated due to the wear of the sheet separation portions 63L and 63R, it is necessary to replace the sheet separation unit 62 that includes the sheet separation portions 63L and 63R, with another.Replacement of Sheet Separation Unit

[0064] Next, a method of replacing the sheet separation unit 62 will be described with reference to FIGS. 3A to 3C. As illustrated in FIG. 3A, for detaching the sheet separation unit 62 from the separation wall 60 of the cassette 11, a user accesses the sheet separation unit 62 from a side on which the user faces the separation slope 60a. In a state where the sheet separation unit 62 is attached to the separation wall 60, the sheet separation unit 62 is restricted from being detached from the separation wall 60, by the holding members 65L and 65R positioned at the holding position.

[0065] In the following description, a side closer to the center of the feeding path 17 in the width direction W is referred to as an inside, and a side far from the center of the feeding path 17 in the width direction W is referred to as an outside. As illustrated in FIG. 4, in a state where the sheet separation unit 62 is attached to the separation wall 60, an end portion 621L of the unit abutment surface 62aL is positioned outside an edge portion 611L of the abutment portion 61L in the width direction W. Similarly, an end portion 621R of the unit abutment surface 62aR is positioned outside an edge portion 611R of the abutment portion 61R in the width direction W. That is, in the width direction W, a distance D5 between the end portion 621L and the end portion 621R is longer than a clearance between the edge portion 611L and the edge portion 611R, that is, than the width D1 of the opening portion 66. Thus, the sheet separation unit 62 is urged by the urging member 64 in the projection direction PD, so that the unit abutment surfaces 62aL and 62aR are pressed against the abutment portions 61L and 61R and held by the separation wall 60.

[0066] In addition, in a case where the holding members 65L and 65R are positioned at the holding position, a distance D6 between the holding members 65L and 65R in the width direction W is shorter than the width D1 and the distance D5. In this case, the width of the opening portion 66 is not the above-described width D1, but the distance D6. If the holding members 65L and 65R are positioned at the holding position and the width of the opening portion 66 is the distance D6, the unit abutment surfaces 62aL and 62aR do not pass through the opening portion 66 even if the posture of the sheet separation unit 62 is changed in a space SP where the urging member 64 is disposed. Thus, the sheet separation unit 62 is restricted from being detached from the separation wall 60. If the holding members 65L and 65R are positioned at the separation position and the width of the opening portion 66 is the width D1, the unit abutment surfaces 62aL and 62aR can pass through the opening portion 66 if the posture of the sheet separation unit 62 is changed in the space SP where the urging member 64 is disposed.

[0067] First, a user positions the holding members 65L and 65R at the separation position by moving the holding member 65L positioned at the holding position, toward the direction indicated by the arrow A1 illustrated in FIG. 3B, and by moving the holding member 65R positioned at the holding position, toward the direction indicated by the arrow A2 illustrated in FIG. 3B. With this operation, the opening area of the opening portion 66 is increased. In other words, the width of the opening portion 66 in the width direction W is increased from the distance D6 to the width D1. In this manner, the lock of the sheet separation unit 62 by the holding members 65L and 65R is released.

[0068] Then, the user changes the posture of the sheet separation unit 62 by pushing the sheet separation unit 62 against the urging force of the urging member 64, into the above-described space SP. Specifically, the user pushes the sheet separation unit 62 so that the unit abutment surfaces 62aL and 62aR are separated from the abutment portions 61L and 61R of the separation wall 60. Furthermore, the user tilts the sheet separation unit 62 with respect to the projection direction PD and the width direction W, and thereby pulls one of the unit abutment surfaces 62aL and 62aR, off from the opening portion 66. After that, the user pulls the whole of the sheet separation unit 62 off from the opening portion 66 by pulling the other of the unit abutment surfaces 62aL and 62aR, off from the opening portion 66. In this manner, the sheet separation unit 62 is detached from the separation wall 60, as illustrated in FIG. 3C.

[0069] For assembling the sheet separation unit 62 to the separation wall 60, the above-described procedures are performed in the order reverse to the order for detaching the sheet separation unit 62 from the separation wall 60. First, a user inserts the sheet separation unit 62 into the opening portion 66 in a state where the holding members 65L and 65R are positioned at the separation position. In this operation, first, the user inserts one of the unit abutment surfaces 62aL and 62aR, into the opening portion 66 by tilting the sheet separation unit 62 with respect to the projection direction PD and the width direction W. Then, the user also inserts the other of the unit abutment surfaces 62aL and 62aR into the opening portion 66 while returning the posture of the sheet separation unit 62 to the posture in which the sheet separation unit 62 is positioned parallel with the width direction W. With this operation, the sheet separation unit 62 is inserted into the opening portion 66 until the sheet separation unit 62 reaches a position at which the unit abutment surfaces 62aL and 62aR face the abutment portions 61L and 61R of the separation wall 60.

[0070] Then the user moves the holding members 65L and 65R to the holding position, so that the sheet separation unit 62 is restricted from falling off from the separation wall 60. In this case, if the user moves the hand off from the sheet separation unit 62, the sheet separation unit 62 is urged by the urging member 64 so that the unit abutment surfaces 62aL and 62aR abut against the abutment portions 61L and 61R. In this manner, the sheet separation portions 63L and 63R of the sheet separation unit 62 are positioned with respect to the separation wall 60 with high accuracy.

[0071] As described above, in the present embodiment, in a state where the sheet separation unit 62 is attached to the separation wall 60, the portion of the sheet separation unit 62 other than the sheet separation portions 63L and 63R does not contact the sheet S fed by the pickup roller 12.

[0072] Next, the positional relationship between the sheet separation portions 63L and 63R, the separation slope 60a, and the sloped surface 62e in a state where the sheet separation unit 62 is attached to the separation wall 60 will be described with reference to FIGS. 14A and 14B. FIG. 14A is a diagram illustrating the positional relationship between the sheet separation portions 63L and 63R, the separation slope 60a, and the sloped surface 62e of the first embodiment. FIG. 14B is a diagram illustrating a state where a sheet is separated from other sheets, one by one, by the sheet separation portions 63L and 63R and the separation slope 60a. FIGS. 14A and 14B are diagrams in which the sheet separation portions 63L and 63R, the separation slope 60a, and the sloped surface 62e are viewed in the width direction W.

[0073] As illustrated in FIG. 14A, the sheet separation portions 63L and 63R of the sheet separation unit 62 project more in the projection direction PD than the separation slope 60a does. In addition, the sloped surface 62e of the sheet separation unit 62 is positioned at a position retracted upstream of the separation slope 60a in the projection direction PD. In addition, as illustrated in FIG. 3A, the sloped surface 62e of the sheet separation unit 62 is disposed between the sheet separation portions 63L and 63R in the width direction W. The first slope 30L and the second slope 30R of the separation slope 60a are respectively disposed outside the sheet separation portions 63L and 63R.

[0074] Thus, as illustrated in FIG. 14B, if a sheet S1, such as a thin paper sheet or a regular paper sheet, is fed by the pickup roller 12, the sheet S1 is conveyed in the sheet feeding direction FD while contacting the sheet separation portions 63L and 63R. In this case, a sheet S2 below the sheet S1 may be fed together with the uppermost sheet S1. The sheet S2 fed together with the sheet S1 contacts the sheet separation portions 63L and 63R. The frictional force between the sheet separation portions 63L and 63R and the sheet S2 is larger than the frictional force between the sheet S1 and the sheet S2. Thus, the sheet S2 is stopped by the sheet separation portions 63L and 63R, and only the sheet S1 is fed by the pickup roller 12. In this manner, the sheet S1 is separated from the sheet S2.

[0075] In addition, in a case where a sheet, such as a thick paper sheet, that has a high stiffness is conveyed, the sheet separation portions 63L and 63R are pushed by the fed sheet. As a result, the sheet separation unit 62 may be moved upstream in the projection direction PD, against the urging force of the urging member 64. Even in this case, since the separation slope 60a receives the load of the sheet, the sheet separation portions 63L and 63R do not move upstream of the separation slope 60a in the projection direction PD. That is, the sheet can be separated from other sheets, one by one, by the sheet separation portions 63L and 63R and the separation slope 60a that become flush with each other.

[0076] Thus, the portion of the sheet separation unit 62 that wears due to the sliding friction between the sheet separation unit 62 and the sheet S is the sheet separation portions 63L and 63R alone. For this reason, the sheet separation unit 62 has only to be replaced with another at a timing at which the sheet separation portions 63L and 63R need replacement. Thus, the sheet separation unit 62 can be replaced with another while the separation wall 60 including the separation slope 60a is left in the sheet feeding apparatus 90 (the apparatus body 1A). In addition, the sheet separation unit 62 can be replaced with another at a proper timing. In other words, the timing at which the sheet separation unit 62 is replaced with another is not affected by the portion of the sheet separation unit 62 other than the sheet separation portions 63L and 63R. That is, any component of the sheet separation unit 62 that is other than the sheet separation portions 63L and 63R and that needs no replacement can be prevented from being replaced with another. In addition, since the sheet separation unit 62 includes no sloped surface flush with the separation slope 60a, the sheet separation unit 62 can be reduced in size and cost.

[0077] In addition, in the present embodiment, the sheet separation unit 62 can be easily attached to and detached from the separation wall 60 only by sliding the holding members 65L and 65R in the width direction W. In addition, the sheet separation unit 62 is urged by the urging member 64, and the unit abutment surfaces 62aL and 62aR abut against the abutment portions 61L and 61R in a state where the sheet separation unit 62 is attached to the separation wall 60. As a result, the sheet separation unit 62 is positioned with respect to the separation wall 60 with high accuracy. With this operation, the accuracy of the relative position between the sheet separation portions 63L and 63R and the separation slope 60a increases, and the sheet separation portions 63L and 63R are positioned at a position at which the sheet separation portions 63L and 63R project more toward the feeding path 17 in the projection direction PD than the separation slope 60a does. As a result, the sheet S can be reliably separated from other sheers, one by one, by the sheet separation portions 63L and 63R and the separation slope 60a, and the failure in conveyance, such as multi-feeding, can be reduced.

[0078] The urging force of the urging member 64 is set larger than the contact pressure produced when a sheet S, such as a thin paper sheet, that has a lower stiffness contacts the sheet separation unit 62, and smaller than the contact pressure produced when a sheet S, such as a thick paper sheet, that has a higher stiffness contacts the sheet separation unit 62. Thus, in a case where the sheet separation unit 62 is pushed by a sheet S, such as a thick paper sheet, that has a higher stiffness (grammage), the sheet separation unit 62 may be moved in a direction in which the unit abutment surfaces 62aL and 62aR are separated from the abutment portions 61L and 61R, against the urging force of the urging member 64. In this case, since the separation slope 60a receives the load of the sheet S even if the sheet S having a higher stiffness is conveyed, the sheet separation portions 63L and 63R can be prevented from retracting upstream of the separation slope 60a in the projection direction PD. As a result, the surface of the sheet separation portions 63L and 63R of the sheet separation unit 62 and the separation slope 60a become flush with each other, so that the sheet S can be separated from other sheets, one by one, by the sheet separation portions 63L and 63R and the separation slope 60a.

[0079] Note that in the present embodiment, each of the separation slope 60a and the sheet contact surface 65a is formed like a flat surface. However, the present disclosure is not limited to this. For example, each of the separation slope 60a and the sheet contact surface 65a may include a plurality of ribs that extends along the conveyance direction of the sheet S.Second Embodiment

[0080] Next, a second embodiment of the present disclosure will be described. In the second embodiment, the holding members 65L and 65R of the first embodiment are not disposed, and locking hooks 162aL and 162aR are formed in the sheet separation unit 62. Thus, the same components as those of the first embodiment are omitted in the drawings, or will be described with the same symbols given to the drawings.

[0081] FIG. 5A is a perspective view illustrating a sheet separation unit 162 of the second embodiment. FIG. 5B is a perspective view illustrating the sheet separation unit 162 detached from the separation wall 60. FIG. 6 is a perspective view illustrating a state where a portion of the sheet separation unit 162 attached to the separation wall 60 is cut off.

[0082] As illustrated in FIGS. 5A to 6, the sheet separation unit 162 that serves as a detachable unit includes a pair of sheet separation portions 63L and 63R, a pair of arm portions 62bL and 62bR, and a pair of locking hooks 162aL and 162aR. The locking hooks 162aL and 162aR that serves as an abutted portion are respectively formed at end portions of the pair of arm portions 62bL and 62bR.

[0083] If the sheet separation unit 162 is inserted into the opening portion 66 of the separation wall 60, the locking hooks 162aL and 162aR are pushed by an edge portion of the opening portion 66, so that the arm portions 62bL and 62bR elastically deform. If the sheet separation unit 162 is inserted into the opening portion 66 until the sheet separation unit 162 reaches an attachment position, the locking hooks 162aL and 162aR are disengaged from the edge portion of the opening portion 66, so that the arm portions 62bL and 62bR elastically returns. Thus, the sheet separation unit 162 is urged by the urging member 64, and the locking hooks 162aL and 162aR abut against and engage with the abutment portions 61L and 61R in a state where the sheet separation unit 162 is attached to the separation wall 60. As a result, the sheet separation unit 162 is positioned with respect to the separation wall 60 with high accuracy. In addition, since the locking hooks 162aL and 162aR are locked by the abutment portions 61L and 61R, the sheet separation unit 162 is restricted from being detached from the separation wall 60.

[0084] Also in the present embodiment, in a state where the sheet separation unit 162 is attached to the separation wall 60, the portion of the sheet separation unit 162 other than the sheet separation portions 63L and 63R does not contact the sheet S fed by the pickup roller 12.

[0085] Thus, the same effects as those of the first embodiment can be produced in a simple configuration. In a case where the sheet separation unit 162 is detached from the separation wall 60, a user can pull the sheet separation unit 162 out of the opening portion 66 by elastically deforming the arm portions 62bL and 62bR such that the arm portions 62bL and 62bR move closer to each other.Third Embodiment

[0086] Next, a third embodiment of the present disclosure will be described. In the third embodiment, instead of the holding members 65L and 65R of the first embodiment, locking members 70L and 70R are disposed. Thus, the same components as those of the first embodiment are omitted in the drawings, or will be described with the same symbols given to the drawings.

[0087] FIG. 7A is a perspective view illustrating a state where the locking members 70L and 70R and a sheet separation unit 62 of the third embodiment are assembled to the separation wall 60. FIG. 7B is a perspective view illustrating a state where the locking members 70L and 70R and the sheet separation unit 62 are detached from the separation wall 60.

[0088] As illustrated in FIGS. 7A and 7B, the locking members 70L and 70R that serve as a restricting member are detachably fixed to the separation wall 60 via screws 71L and 71R. In a case where the sheet separation unit 62 is assembled to the separation wall 60, a user inserts the sheet separation unit 62 into the opening portion 66 in a state where the locking members 70L and 70R are detached from the separation wall 60. In this case, the user inserts the sheet separation unit 62 into the opening portion 66 until the sheet separation unit 62 reaches a position at which the unit abutment surfaces 62aL and 62aR of the sheet separation unit 62 face the abutment portions 61L and 61R of the separation wall 60.

[0089] Then the user fixes the locking members 70L and 70R to the separation wall 60, so that the sheet separation unit 62 is restricted from falling off from the separation wall 60. In this case, if the user moves the hand off from the sheet separation unit 62, the sheet separation unit 62 is urged by the urging member 64 so that the unit abutment surfaces 62aL and 62aR abut against the abutment portions 61L and 61R. In this manner, the sheet separation portions 63L and 63R of the sheet separation unit 62 are positioned with respect to the separation wall 60 with high accuracy. With this operation, the accuracy of the relative position between the sheet separation portions 63L and 63R and the separation slope 60a increases, and the sheet separation portions 63L and 63R are positioned at a position at which the sheet separation portions 63L and 63R project more toward the feeding path 17 in the projection direction PD than the separation slope 60a does. As a result, the sheet S can be reliably separated from other sheers, one by one, by the sheet separation portions 63L and 63R and the separation slope 60a, and the failure in conveyance, such as multi-feeding, can be reduced.

[0090] In addition, since the locking members 70L and 70R are firmly fixed to the separation wall 60 via the screws 71L and 71R, the sheet separation unit 62 is not easily detached from the separation wall 60 at a timing other than the timing at which the sheet separation unit 62 is replaced with another.Fourth Embodiment

[0091] Next, a fourth embodiment of the present disclosure will be described. In the fourth embodiment, instead of the holding members 65L and 65R of the first embodiment, a cover 67 is disposed. Thus, the same components as those of the first embodiment are omitted in the drawings, or will be described with the same symbols given to the drawings.

[0092] FIG. 8A is a perspective view illustrating a state where the cover 67 of the fourth embodiment is positioned at a closed position. FIG. 8B is a perspective view illustrating a state where the cover 67 is positioned at an open position. FIG. 8C is a perspective view illustrating a state where the sheet separation unit 62 is detached from the separation wall 60.

[0093] As illustrated in FIGS. 8A to 8C, the cover 67 is supported such that the cover 67 can pivot around a rotation shaft 67a with respect to the separation wall 60, and that the cover 67 can be opened and closed with respect to the separation wall 60. The cover 67 includes a sheet contact surface 67b that can contact the sheet S fed by the pickup roller 12, and openings 67cL and 67cR that serve as a second opening portion formed in the sheet contact surface 67b. As illustrated in FIG. 8A, in a state where the cover 67 is positioned at the closed position, the sheet contact surface 67b is located side by side with the separation slope 60a in the width direction W. In this case, the sheet contact surface 67b is positioned upstream of the separation slope 60a in the projection direction PD. In other words, in the projection direction PD, the amount of projection of the sheet contact surface 67b toward the feeding path 17 is smaller than the amount of projection of the separation slope 60a toward the feeding path 17. Thus, the sheet contact surface 67b does not prevent the sheet S from contacting the separation slope 60a.

[0094] The openings 67cL and 67cR are formed at positions that correspond to the positions of the sheet separation portions 63L and 63R of the sheet separation unit 62 attached to the separation wall 60. In addition, the openings 67cL and 67cR are formed so that the sheet separation portions 63L and 63R project from the openings 67cL and 67cR in a state where the sheet separation unit 62 is attached to the separation wall 60.

[0095] The cover 67 can open and close the opening portion 66 that serves as a first opening portion. As illustrated in FIG. 8B, the cover 67 opens the opening portion 66 by rotating from the closed position to the open position. In this state, the sheet separation unit 62 can be inserted into the opening portion 66 and detached from the separation wall 60, as described in the first embodiment.

[0096] Note that also in the present embodiment, the unit abutment surfaces 62aL and 62aR of the sheet separation unit 62 abut against the abutment portions 61L and 61R of the separation wall 60 in a state where the sheet separation unit 62 is inserted in the opening portion 66 and urged by the urging member 64. If the cover 67 is positioned at the closed position, the sheet separation portions 63L and 63R of the sheet separation unit 62 respectively project from the openings 67cL and 67cR of the cover 67 toward the feeding path 17. With this operation, the accuracy of the relative position between the sheet separation portions 63L and 63R and the separation slope 60a increases, and the sheet separation portions 63L and 63R are positioned at a position at which the sheet separation portions 63L and 63R project downstream of the separation slope 60a in the projection direction PD. As a result, the sheet S can be reliably separated from other sheers, one by one, by the sheet separation portions 63L and 63R and the separation slope 60a, and the failure in conveyance, such as multi-feeding, can be reduced.

[0097] As described above, also in the present embodiment, the same effects as those of the first embodiment can be produced. In addition, in the present embodiment, the opening portion 66 that has a large opening area can be opened by opening the cover 67 from the closed position to the open position. Thus, the replacement work of the sheet separation unit 62 can be performed through the opening portion 66. As a result, the replacement work of the sheet separation unit 62 can be performed easily, so that the workability of replacement can be improved. In addition, the cover 67 includes the sheet contact surface 67b disposed side by side with the sheet separation portions 63L and 63R and the separation slope 60a in the width direction W, in a state where the cover 67 is positioned at the closed position. Thus, even if the opening portion 66 is made large, the opening portion 66 does not affect the separation performance for the sheet S, so that the sheet S can be separated properly from other sheets, one by one.

[0098] Note that in the present embodiment, each of the separation slope 60a and the sheet contact surface 67b is formed like a flat surface. However, the present disclosure is not limited to this. For example, each of the separation slope 60a and the sheet contact surface 67b may include a plurality of ribs that extends along the conveyance direction of the sheet S.Fifth Embodiment

[0099] Next, a fifth embodiment of the present disclosure will be described. In the fifth embodiment, the arrangement of the cover 67 of the fourth embodiment is changed. Thus, the same components as those of the fourth embodiment are omitted in the drawings, or will be described with the same symbols given to the drawings.

[0100] FIG. 9A is a perspective view illustrating a state where a cover 167 of the fifth embodiment is positioned at a closed position. FIG. 9B is a perspective view illustrating a state where the cover 167 is positioned at an open position. FIG. 9C is a perspective view illustrating a state where the sheet separation unit 62 is detached from the separation wall 60. FIG. 10 is a perspective view illustrating a state where a portion of the sheet separation unit 62 attached to the separation wall 60 and the cover 167 is cut off.

[0101] As illustrated in FIGS. 9A and 9B, the separation slope 60a of the separation wall 60 includes openings 60bL and 60bR which serve as a third opening portion, and through which the sheet separation portions 63L and 63R project. As illustrated in FIGS. 9A to 9C, the cover 167 is supported such that the cover 167 can pivot around a rotation shaft 167a with respect to the separation wall 60, and that the cover 167 can be opened and closed with respect to the separation wall 60. The cover 167 is disposed on the back side of the separation slope 60a, and can open and close an opening portion 166 disposed on the back side of the separation slope 60a. That is, the opening portion 166 is opened toward a direction opposite to the feeding path 17 with respect to the separation slope 60a. In other words, the opening portion 166 is opened toward the upstream side in the projection direction PD. As illustrated in FIGS. 9B and 9C, the cover 67 opens the opening portion 166 by rotating from the closed position to the open position. In this state, the sheet separation unit 62 can be inserted into the opening portion 166 and detached from the separation wall 60, as described in the first embodiment. That is, in the present embodiment, the sheet separation unit 62 is attached to and detached from the separation wall 60, from the back side (opposite side) of the separation slope 60a. However, the configuration for positioning the sheet separation unit 62 with respect to the separation wall 60 is the same as that of the first embodiment.

[0102] In the present embodiment, as illustrated in FIG. 9C, a width D3 of the opening portion 166 is longer than a distance D2 (see FIG. 9A) between the sheet separation portions 63L and 63R in the width direction W. Thus, since the opening portion 166 has a large opening area, the sheet separation unit 62 can be easily attached to the opening portion 166, so that the workability of replacement of the sheet separation unit 62 can be improved.

[0103] As illustrated in FIGS. 9B and 9C, for detaching the sheet separation unit 62 from the separation wall 60 of the cassette 11, a user opens the cover 167 to the open position, and accesses the sheet separation unit 62 from the back side of the separation slope 60a. The opening portion 166 that has a large opening area can be opened by opening the cover 167, so that the replacement work of the sheet separation unit 62 can be performed through the opening portion 166.

[0104] As illustrated in FIGS. 9C and 10, the user then pulls the sheet separation unit 62 toward the front side, and separates the unit abutment surfaces 62aL and 62aR from the abutment portions 61L and 61R of the separation wall 60. With this operation, the sheet separation unit 62 can be detached from the separation wall 60, as illustrated in FIG. 9C.

[0105] For assembling the sheet separation unit 62 to the separation wall 60, the above-described procedures are performed in the order reverse to the order for detaching the sheet separation unit 62 from the separation wall 60. First, a user inserts the sheet separation unit 62 into the opening portion 166 in a state where the cover 167 is positioned at the open position. In this case, the user inserts the sheet separation unit 62 into the opening portion 166 until the sheet separation unit 62 reaches a position at which the unit abutment surfaces 62aL and 62aR of the sheet separation unit 62 face the abutment portions 61L and 61R of the separation wall 60.

[0106] Then the user moves the cover 167 to the closed position as illustrated in FIG. 9A, so that the sheet separation unit 62 is restricted from falling off from the separation wall 60. The urging member 64 is supported by the cover 167. Thus, if the user moves the cover 167 from the open position to the closed position, the sheet separation unit 62 is urged by the urging member 64 so that the unit abutment surfaces 62aL and 62aR abut against the abutment portions 61L and 61R.

[0107] In this case, the sheet separation portions 63L and 63R of the sheet separation unit 62 respectively project from the openings 60bL and 60bR of the separation slope 60a. In other words, when the cover 167 is closed after the sheet separation unit 62 is inserted into the opening portion 166, the sheet separation portions 63L and 63R project from the openings 60bL and 60bR toward the feeding path 17. With this operation, the accuracy of the relative position between the sheet separation portions 63L and 63R and the separation slope 60a increases, and the sheet separation portions 63L and 63R are positioned at a position at which the sheet separation portions 63L and 63R project downstream of the separation slope 60a in the projection direction PD. As a result, the sheet S can be reliably separated from other sheers, one by one, by the sheet separation portions 63L and 63R and the separation slope 60a, and the failure in conveyance, such as multi-feeding, can be reduced.

[0108] In the present embodiment, the opening portion 166 that has a large opening area and that is disposed on the back side of the separation slope 60a can be opened by opening the cover 167 from the closed position to the open position. Thus, the replacement work of the sheet separation unit 62 can be performed through the opening portion 166. As a result, the replacement work of the sheet separation unit 62 can be performed easily even in a case where the opening portion cannot be disposed on the separation slope 60a side or where the replacement work cannot be performed from the separation slope 60a side, so that the workability of replacement can be improved. In addition, since the opening portion 166 and the cover 167 are disposed on the back side of the separation slope 60a, the opening portion 66 does not affect the separation performance for the sheet S even if the opening portion 166 is made large, so that the sheet S can be separated properly from other sheets, one by one.

[0109] FIG. 11A is a perspective view illustrating a modification of the fifth embodiment in a case where the separation wall 60 and the sheet separation unit 62 are disposed in the apparatus body 1A. FIG. 11B is a perspective view illustrating the modification of the fifth embodiment in a state where the cassette 11 is drawn in a direction indicated by an arrow B. As illustrated in FIGS. 11A and 11B, if the separation wall 60 and the sheet separation unit 62 are disposed in the apparatus body 1A, it may be difficult to access the separation slope 60a side and perform the replacement work of the sheet separation unit 62 from the separation slope 60a side, due to the configuration and space. Even in such a configuration, since the opening portion 166 and the cover 167 are disposed on the back side of the separation slope 60a, the replacement work of the sheet separation unit 62 can be performed easily, so that the workability of replacement can be improved.

[0110] Note that in the present embodiment, the separation slope 60a is formed like a flat surface. However, the present disclosure is not limited to this. For example, the separation slope 60a may include a plurality of ribs that extends along the conveyance direction of the sheet S.Sixth Embodiment

[0111] Next, a sixth embodiment of the present disclosure will be described. In the sixth embodiment, the arrangement of the cover 167 and the opening portion 166 of the fifth embodiment is changed. Thus, the same components as those of the fifth embodiment are omitted in the drawings, or will be described with the same symbols given to the drawings.

[0112] FIG. 12A is a perspective view illustrating a state where a cover 267 of the sixth embodiment is positioned at a closed position. FIG. 12B is a perspective view illustrating a state where the cover 267 is positioned at an open position. FIG. 12C is a perspective view illustrating a state where the sheet separation unit 62 is detached from the separation wall 60.

[0113] As illustrated in FIGS. 12A and 12B, the separation slope 60a of the separation wall 60 includes the openings 60bL and 60bR through which the sheet separation portions 63L and 63R project. As illustrated in FIGS. 12A to 12C, the cover 267 is supported such that the cover 267 can pivot around a rotation shaft 267a with respect to the separation wall 60, and that the cover 267 can be opened and closed with respect to the separation wall 60. The cover 267 is disposed in a top surface 60c of the separation wall 60, and can open and close an opening portion 266 disposed in the top surface 60c. That is, the opening portion 266 is opened toward a vertical direction. As illustrated in FIGS. 12B and 12C, the cover 267 opens the opening portion 266 by rotating from the closed position to the open position. In this state, the sheet separation unit 62 can be inserted into the opening portion 266 and detached from the separation wall 60, as described in the first embodiment. That is, in the present embodiment, the sheet separation unit 62 is attached to and detached from the separation wall 60, from the top surface 60c of the separation slope 60a. However, the configuration for positioning the sheet separation unit 62 with respect to the separation wall 60 is the same as that of the first embodiment.

[0114] In the present embodiment, as illustrated in FIG. 12B, a width D4 of the opening portion 266 is longer than the distance D2 between the sheet separation portion 63L and the sheet separation portion 63R in the width direction W. Thus, since the opening portion 266 has a large opening area, the sheet separation unit 62 can be easily attached to the opening portion 266, so that the workability of replacement of the sheet separation unit 62 can be improved.

[0115] For detaching the sheet separation unit 62 from the separation wall 60 of the cassette 11, a user opens the cover 267 to the open position as illustrated in FIGS. 12B and 12C, and accesses the sheet separation unit 62 from the top surface 60c side of the separation wall 60. The opening portion 266 that has a large opening area can be opened by opening the cover 267, so that the replacement work of the sheet separation unit 62 can be performed through the opening portion 266.

[0116] The user then pulls the sheet separation unit 62 upward, and separates the unit abutment surfaces 62aL and 62aR from the abutment portions 61L and 61R of the separation wall 60, as illustrated in FIG. 12C. With this operation, the sheet separation unit 62 can be detached from the separation wall 60.

[0117] For assembling the sheet separation unit 62 to the separation wall 60, the above-described procedures are performed in the order reverse to the order for detaching the sheet separation unit 62 from the separation wall 60. First, a user inserts the sheet separation unit 62 into the opening portion 266 in a state where the cover 267 is positioned at the open position. In this case, the user inserts the sheet separation unit 62 into the opening portion 266 until the sheet separation unit 62 reaches a position at which the unit abutment surfaces 62aL and 62aR of the sheet separation unit 62 face the abutment portions 61L and 61R of the separation wall 60.

[0118] Then the user moves the cover 267 to the closed position as illustrated in FIG. 12A, so that the sheet separation unit 62 is restricted from falling off from the separation wall 60. In this case, if the user moves the hand off from the sheet separation unit 62, the sheet separation unit 62 is urged by the urging member 64 so that the unit abutment surfaces 62aL and 62aR abut against the abutment portions 61L and 61R. The urging member 64 is supported by the separation wall 60. In this case, the sheet separation portions 63L and 63R of the sheet separation unit 62 respectively project from the openings 60bL and 60bR of the separation slope 60a. With this operation, the accuracy of the relative position between the sheet separation portions 63L and 63R and the separation slope 60a increases, and the sheet separation portions 63L and 63R are positioned at a position at which the sheet separation portions 63L and 63R project downstream of the separation slope 60a in the projection direction PD. As a result, the sheet S can be reliably separated from other sheers, one by one, by the sheet separation portions 63L and 63R and the separation slope 60a, and the failure in conveyance, such as multi-feeding, can be reduced.

[0119] As described above, also in the present embodiment, the same effects as those of the first embodiment can be produced. In addition, in the present embodiment, the opening portion 266 that has a large opening area and that is formed in the top surface 60c of the separation wall 60 can be opened by opening the cover 267 from the closed position to the open position. Thus, the replacement work of the sheet separation unit 62 can be performed through the opening portion 66. As a result, the replacement work of the sheet separation unit 62 can be performed easily even in a case where the opening portion cannot be disposed on the separation slope 60a side or the back side of the separation slope 60a, so that the workability of replacement can be improved. In addition, since the opening portion 266 and the cover 267 are disposed in the top surface 60c of the separation wall 60, the opening portion 266 does not affect the separation performance for the sheet S even if the opening portion 266 is made large, so that the sheet S can be separated properly from other sheets, one by one.

[0120] FIG. 13 is a diagram illustrating one example of an image forming apparatus 1B that has the configuration of the sixth embodiment. As illustrated in FIG. 13, a sheet feeding apparatus 190 that has the same configuration as that of the sheet feeding apparatus 90 is disposed below the sheet feeding apparatus 90, and is connected to the image forming apparatus 1B. In this case, the sheet S fed from the lower sheet feeding apparatus 190 is conveyed upward through a conveyance path 18 disposed at the upper sheet feeding apparatus 90.

[0121] In such a configuration, since the conveyance path 18 is positioned on the back side of the separation slope 60a of the separation wall 60 of the sheet feeding apparatus 90, it is difficult to dispose an opening portion on the back side of the separation slope 60a and perform the replacement work of the sheet separation unit 62 through the opening portion. In addition, there is a case where an exterior surface of the image forming apparatus is disposed on the back side of the separation slope 60a of the separation wall 60. Also in this case, it is difficult to dispose a large opening portion on the back side of the separation slope 60a, for the replacement work of the sheet separation unit 62.

[0122] In the present embodiment, however, since the opening portion 266 and the cover 267 are disposed in the top surface 60c of the separation wall 60, the replacement work of the sheet separation unit 62 can be performed easily, so that the workability of replacement can be improved.

[0123] Note that in the present embodiment, the separation slope 60a is formed like a flat surface. However, the present disclosure is not limited to this. For example, the separation slope 60a may include a plurality of ribs that extends along the conveyance direction of the sheet S.Other Embodiments

[0124] Note that in the above-described embodiments, the urging member 64 urges the sheet separation unit for positioning the sheet separation unit with respect to the separation wall 60. However, the configuration of the urging member 64 is not limited to this. As described above, the urging member 64 may include the compression coil spring 64a supported, for example, by the separation wall 60, and the plate member 64b that is fixed to the compression coil spring 64a and that can abut against the sheet separation unit 62. In another case, the urging member 64 may be constituted by an elastic member alone, such as a spring, a rubber, or a sponge.

[0125] In addition, in the above-described embodiments, the separation wall 60 may be disposed in the cassette 11 as described with reference to FIGS. 2A and 2B, or may be disposed in the apparatus body 1A as described with reference to FIGS. 11A and 11B.

[0126] In addition, although the above-described embodiments have been described for the case where the electrophotographic image forming apparatus 1 is used, the present disclosure is not limited to this. For example, the present disclosure may also be applied to an ink-jet image forming apparatus that forms images on sheets by injecting ink from a nozzle.

[0127] In the present disclosure, the detachable unit can be replaced with another while the separation surface is left in the sheet feeding apparatus.

[0128] While the present disclosure has been described with reference to embodiments, it is to be understood that the present disclosure is not limited to the disclosed 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.

[0129] This application claims the benefit of Japanese Patent Application No. 2024-165661, filed September 24, 2024, 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 rotary feeding member configured to feed the sheet stacked on the stacking portion, toward an image forming portion in a sheet feeding direction; a first separation portion including a separation surface disposed so as to contact the sheet fed by the rotary feeding member; and a detachable unit detachably attached to the first separation portion, the detachable unit including a second separation portion that contacts a sheet fed by the rotary feeding member so as to separate the sheet, together with the separation surface, one by one, wherein a direction that intersects both the sheet feeding direction and a rotation-axis direction of the rotary feeding member, and that extends from the separation surface toward the rotary feeding member is defined as a projection direction, the second separation portion is positioned downstream of the separation surface in the projection direction in a state where the detachable unit is attached to the first separation portion, and another portion of the detachable unit other than the second separation portion is positioned upstream of the separation surface in the projection direction in a state where the detachable unit is attached to the first separation portion.

2. The sheet feeding apparatus according to claim 1, wherein the first separation portion includes an opening portion into which the detachable unit to be attached to the first separation portion is inserted.

3. The sheet feeding apparatus according to claim 2, wherein the opening portion is opened toward a downstream side in the projection direction.

4. The sheet feeding apparatus according to claim 2, wherein the opening portion is opened toward an upstream side in the projection direction.

5. The sheet feeding apparatus according to claim 2, wherein the opening portion is opened in a vertical direction.

6. The sheet feeding apparatus according to claim 2, wherein the detachable unit includes a first end and a second end in the rotation-axis direction, the second separation portion includes: a first sheet-separation portion disposed at a position closer to the first end than to the second end in the rotation-axis direction; and a second sheet-separation portion disposed at a position closer to the second end than to the first end in the rotation-axis direction, and a width of the opening portion is longer than a distance between the first sheet-separation portion and the second sheet-separation portion in the rotation-axis direction.

7. The sheet feeding apparatus according to claim 2, further comprising a restricting member configured to restrict the detachable unit, inserted in the opening portion, from being detached from the first separation portion.

8. The sheet feeding apparatus according to claim 7, wherein the restricting member is configured to move between a restricting position and an allowable position, the restricting position being a position at which the restricting member restricts the detachable unit from being detached from the first separation portion, the allowable position being a position at which the restricting member allows the detachable unit to be detached from the first separation portion.

9. The sheet feeding apparatus according to claim 8, wherein the restricting member covers a part of the opening portion at the restricting position, and increases an opening area of the opening portion by moving from the restricting position to the allowable position.

10. The sheet feeding apparatus according to claim 7, wherein the restricting member is configured to be detachably fixed to the first separation portion.

11. The sheet feeding apparatus according to claim 2, wherein the first separation portion includes an abutment portion, the detachable unit includes an abutted portion configured to abut against the abutment portion, and the sheet feeding apparatus further includes an urging member configured to position the detachable unit with respect to the first separation portion by urging the detachable unit such that the abutted portion abuts against the abutment portion in a state where the detachable unit is attached to the first separation portion.

12. The sheet feeding apparatus according to claim 11, wherein the urging member is configured to urge the detachable unit in the projection direction in a state where the detachable unit is attached to the first separation portion, and the abutted portion is positioned upstream of the abutment portion in the projection direction in a state where the detachable unit is attached to the first separation portion.

13. The sheet feeding apparatus according to claim 11, wherein the detachable unit is configured to move upstream in the projection direction against an urging force of the urging member while the second separation portion is pushed by a sheet fed by the rotary feeding member.

14. The sheet feeding apparatus according to claim 11, wherein the abutted portion is configured to restrict the detachable unit from being detached from the first separation portion by being locked by the abutment portion in a state where the detachable unit is inserted in the opening portion.

15. The sheet feeding apparatus according to claim 2, further comprising a cover configured to open and close the opening portion.

16. The sheet feeding apparatus according to claim 15, wherein the opening portion is a first opening portion, the cover includes a second opening portion, and the second separation portion projects from the second opening portion in the projection direction when the cover is closed after the detachable unit is inserted into the first opening portion.

17. The sheet feeding apparatus according to claim 1, wherein at least a portion of the second separation portion has a coefficient of friction higher than that of the separation surface.

18. An image forming apparatus comprising: the sheet feeding apparatus according to claim 1; and the image forming portion configured to form an image on a sheet fed from the sheet feeding apparatus.

19. A sheet feeding apparatus comprising: a stacking portion on which a sheet is stacked; a rotary feeding member configured to feed the sheet stacked on the stacking portion, toward an image forming portion in a sheet feeding direction; a first separation portion including a separation surface disposed so as to contact the sheet fed by the rotary feeding member; and a detachable unit detachably attached to the first separation portion, the detachable unit including a second separation portion that contacts a sheet fed by the rotary feeding member so as to separate the sheet, together with the separation surface, one by one, wherein a direction that intersects both the sheet feeding direction and a rotation-axis direction of the rotary feeding member, and that extends from the separation surface toward the rotary feeding member is defined as a projection direction, the second separation portion is positioned downstream of the separation surface in the projection direction in a state where the detachable unit is attached to the first separation portion, and another portion of the detachable unit other than the second separation portion is configured not to contact the sheet fed by the rotary feeding member in a state where the detachable unit is attached to the first separation portion.

20. An image forming apparatus comprising: the sheet feeding apparatus according to claim 19; and the image forming portion configured to form an image on a sheet fed from the sheet feeding apparatus.

Images