Patent Grant
11427427
The present disclosure relates to a sheet stacking apparatus that discharges a sheet, a sheet processing apparatus that process a sheet, and an image forming system that forms an image on a sheet.
In a sheet stacking apparatus in which sheets on which images have been formed are stacked in an image forming apparatus such as a copier or a printer, a stacking portion such as a tray that is lifted and lowered with sheets supported thereon is used. A sheet abutting portion that abuts the trailing end of the sheets discharged onto the stacking portion to regulate the sheet position is provided in a member positioned upstream of the stacking portion in a sheet discharge direction such as the casing of the image forming apparatus.
When the stacking portion supporting sheets is lifted or lowered, there is a possibility that problems such as noises and damage to the trailing end of the sheets arise as a result of the trailing end of the sheets rubbing the sheet abutting portion. Japanese Patent Laid-Open No. 2002-308507 discloses a configuration in which a belt member capable of abutting the trailing end of a sheet is disposed upstream of a discharge tray in a sheet discharge direction is provided. According to this document, as a result of the friction between the belt member and the sheet on the discharge tray, the belt member rotates in accordance with the lifting and lowering of the discharge tray.
In the configuration disclosed in Japanese Patent Laid-Open No. 2002-308507, the belt member moves in accordance with the lifting and lowering of the discharge tray irrespective of the position of the discharge tray.
The present disclosure provides a sheet stacking apparatus and an image forming apparatus that can suppress occurrence of an issue caused by rubbing of a sheet.
According to an aspect of the present disclosure, a sheet stacking apparatus includes a discharge unit configured to discharge a sheet, a stacking portion on which sheets discharged by the discharge unit are stacked, a lifting unit configured to lift and lower the stacking portion, a first abutting portion configured to abut a trailing end of the sheets stacked on the stacking portion in a sheet discharge direction of the discharge unit, wherein the first abutting portion is configured not to move in an up-down direction, and a second abutting portion configured to abut the trailing end of the sheets stacked on the stacking portion, wherein the first abutting portion supports the second abutting portion such that the second abutting portion is movable in the up-down direction, wherein, in a case where the stacking portion is lowered from a first position to a second position below the first position, the second abutting portion is configured not to move in accordance with the stacking portion, and wherein, in a case where the stacking portion is further lowered beyond the second position, the second abutting portion is configured to move in accordance with the stacking portion.
Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Exemplary embodiments of the present disclosure will be described below with reference to drawings.
In the description below, a horizontal component of a sheet discharge direction in which a sheet stacking apparatus serving as a sheet discharge apparatus discharges a sheet will be referred to as a Y direction, a sheet width direction of the sheet intersecting with the Y direction will be referred to as an X direction, and the vertical direction will be referred to as a Z direction. The X direction serves as a main scanning direction in image formation. The X direction, the Y direction, and the Z direction are preferably perpendicular to one another.
The document feeding apparatus 3 conveys a document placed on a document tray 18 to image reading portions 16 and 19. The image reading portions 16 and 19 are image sensors that read image information from respective document surfaces, and both surfaces of a document are read in one time of conveyance of the document. The document whose image information has been read is discharged onto a document discharge portion 20. In addition, the image reading apparatus 2 can read image information from a still document set on a platen glass, by reciprocating the image reading portion 16 by a driving device 17. Examples of the still document include documents such as booklet documents for which the document feeding apparatus 3 cannot be used.
The image forming apparatus 1 is an electrophotographic apparatus including an image forming portion 1B of a direct transfer system. The image forming portion 1B includes a cartridge 8 including a photosensitive drum 9, and a laser scanner unit 15 disposed above the cartridge 8. In the case of performing an image forming operation, the surface of the rotating photosensitive drum 9 is charged, and the laser scanner unit 15 draws an electrostatic latent image on the surface of the photosensitive drum 9 by exposing the photosensitive drum 9 on the basis of image information. The electrostatic latent image born on the photosensitive drum 9 is developed into a toner image by charged toner particles, and the toner image is conveyed to a transfer portion where the photosensitive drum 9 and a transfer roller 10 face each other. The controller of the image forming apparatus 1, which is a printer controller that will be described later, executes an image forming operation by the image forming portion 1B on the basis of image information read by the image reading portions 16 and 19 or image information received from an external computer via a network.
The image forming apparatus 1 includes a plurality of feeding apparatuses 6 that feed sheets serving as recording materials one by one at predetermined intervals. A sheet fed from a feeding apparatus 6 is conveyed to the transfer portion after the skew thereof is corrected by registration rollers 7, and in the transfer portion, the toner image born on the photosensitive drum 9 is transferred thereto. A fixing unit 11 is disposed downstream of the transfer portion in a sheet conveyance direction. The fixing unit 11 includes a rotary member pair that nips and conveys the sheet, and a heat generating member such as a halogen lamp for heating the toner image, and performs image fixing processing on the toner image on the sheet by heating and pressurizing the toner image.
In the case of discharging the sheet having undergone image formation to the outside of the image forming apparatus 1, the sheet having passed through the fixing unit 11 is conveyed to the post-processing apparatus 4 via a horizontal conveyance portion 14. In the case of a sheet image formation on a first surface of which is finished in duplex printing, the sheet having passed through the fixing unit 11 is passed onto reverse conveyance rollers 12, switched back and conveyed by the reverse conveyance rollers 12, and conveyed to the registration rollers 7 again via a reconveyance portion 13. Then, an image is formed on a second surface of the sheet as a result of the sheet passing through the transfer portion and the fixing unit 11 again, and then the sheet is conveyed to the post-processing apparatus 4 via the horizontal conveyance portion 14.
The image forming portion 1B described above is an example of an image forming unit that forms an image on a sheet, and an electrophotographic unit of an intermediate transfer system that transfers a toner image formed on a photosensitive member onto a sheet via an intermediate transfer member may be used therefor. In addition, a printing unit of an inkjet system or an offset printing system may be used as the image forming unit.
Post-Processing Apparatus
The post-processing apparatus 4 includes a binding processing portion 4A that performs a binding process on sheets received from the image forming apparatus 1, and discharges the sheets as a sheet bundle. In addition, the post-processing apparatus 4 is also capable of simply discharging a sheet received from the image forming apparatus 1 without performing a binding process thereon. To be noted, the binding processing portion 4A is an example of a processing unit that performs a process on a sheet, and a processing portion that performs a punching process, a processing portion that performs a folding process, or the like may be provided in place of or in addition to the binding processing portion 4A.
The post-processing apparatus 4 includes an entry path 81, an in-body discharge path 82, a first discharge path 83, and a second discharge path 84 as conveyance paths for conveying a sheet, and an upper discharge portion 300A and a lower discharge portion 300B are provided as discharge destinations onto which a sheet is discharged. The entry path 81 serves as a conveyance path through which a sheet is received from the outside of the post-processing apparatus 4 and conveyed. The first discharge path 83 serves as a first conveyance path through which the sheet received from the image forming apparatus 1 is discharged onto the upper discharge portion 300A. The in-body discharge path 82 serves as a second conveyance path which is branched from the first conveyance path and through which a sheet reversed and conveyed in the first conveyance path is conveyed toward the binding processing portion 4A. The second discharge path 84 serves as a third conveyance path through which the sheet conveyed to the binding processing portion 4A is discharged onto the lower discharge portion 300B.
In the entry path 81, inlet rollers 21, pre-buffer rollers 22, an entrance sensor 27, and a lateral position detection sensor are disposed. In the first discharge path 83, discharging/reversing rollers 24 serving as a reverse conveyance unit are disposed. In the in-body discharge path 82, in-body discharge rollers 26, intermediate conveyance rollers 28, kick-out rollers 29, and a pre-intermediate supporting sensor 38 are disposed. Each roller described above functions as a conveyance unit that conveys a sheet. In the second discharge path 84, bundle discharge rollers 36 are disposed. The entrance sensor 27 and the pre-intermediate supporting sensor 38 each serve as an example of a sheet detection portion that detects passage of a sheet at a predetermined detection position in a conveyance path in a sheet processing apparatus. As the entrance sensor 27 and the pre-intermediate supporting sensor 38, optical sensors that detect presence/absence of a sheet at the detection position by using light as will be described later can be used.
A sheet conveyance path in the post-processing apparatus 4 will be described below. To be noted, a buffering operation by a buffering portion 4B including the discharging/reversing rollers 24, and the detailed configuration and operation of the binding processing portion 4A will be described later.
The sheet discharged from the horizontal conveyance portion 14 of the image forming apparatus 1 is received by the inlet rollers 21, and is conveyed toward the pre-buffer rollers 22 through the entry path 81. The entrance sensor 27 detects the sheet at a detection position between the inlet rollers 21 and the pre-buffer rollers 22. In addition, the lateral position detection sensor detects the position of the sheet in the sheet width direction (i.e., in the X direction) at a position between the detection position of the entrance sensor 27 and the pre-buffer rollers 22. In the description below, this position will be referred to as a lateral position of the sheet. The pre-buffer rollers 22 convey the sheet received from the inlet rollers 21 toward the first discharge path 83.
To be noted, at a predetermined timing after the entrance sensor 27 has detected passage of a trailing end of the sheet, the sheet conveyance speed of the pre-buffer rollers 22 is increased to a speed higher than the conveyance speed in the horizontal conveyance portion 14. In addition, the sheet conveyance speed of the inlet rollers 21 may be set to be higher than that in the horizontal conveyance portion 14, and the conveyance speed may be increased by the inlet rollers 21 upstream of the pre-buffer rollers 22. In this case, it is preferable that a one-way clutch is disposed between a conveyance roller of the horizontal conveyance portion 14 and a motor that drives the conveyance roller such that the conveyance roller idles when the sheet is pulled by the inlet rollers 21.
In the case where the discharge destination of the sheet is the upper discharge portion 300A, the discharging/reversing rollers 24 discharge the sheet received from the pre-buffer rollers 22 onto the discharge portion 300A serving as a first discharge unit. In this case, the discharging/reversing rollers 24 decelerate to a predetermined discharge speed at a predetermined timing after the trailing end of the sheet has passed through the pre-buffer rollers 22.
In the case where the discharge destination of the sheet is the lower discharge portion 300B, the discharging/reversing rollers 24 switch back and convey the sheet received from the pre-buffer rollers 22 toward the in-body discharge path 82. A non-return flap 23 is provided at a branching portion upstream of the discharging/reversing rollers 24 in the sheet discharge direction of the discharging/reversing rollers 24 where the entry path 81 and the in-body discharge path 82 branch from the first discharge path 83. The non-return flap 23 has a function of suppressing backward movement of the sheet switched back by the discharging/reversing rollers 24 into the entry path 81.
The in-body discharge rollers 26, the intermediate conveyance rollers 28, and the kick-out rollers 29 disposed in the in-body discharge path 82 convey the sheet received from the discharging/reversing rollers 24 toward the binding processing portion 4A while passing the sheet onto one another. The pre-intermediate supporting sensor 38 detects the sheet at a position between the intermediate conveyance rollers 28 and the kick-out rollers 29.
The binding processing portion 4A includes a stapler 51 serving as a binding unit of the present embodiment, and staples a predetermined position of the sheet bundle by the stapler 51 after aligning a plurality of sheets received from the in-body discharge path 82. The sheet bundle stapled by the binding processing portion 4A is passed onto the bundle discharge rollers 36 through the second discharge path 84 serving as a third conveyance path, and is discharged onto the discharge portion 300B by the bundle discharge rollers 36 serving as a second discharge unit.
The upper and lower discharge portions 300A and 300B described above are each an example of a sheet stacking apparatus by which sheets are discharged and stacked. To be noted, the discharge portions 300A and 300B each have a function of performing a discharge method of changing a discharge position of a sheet among a plurality of positions in the sheet width direction each time a predetermined number of sheets are discharged. This discharge method is also referred to as jog discharge.
The discharge portions 300A and 300B are each provided with a tray 302 serving as a stacking portion configured to support sheets thereon. The trays 302 are each capable of moving up and down, that is, capable of being lifted and lowered, with respect to the apparatus body 40 of the post-processing apparatus 4 by a lifting mechanism 330 that will be described later. The tray 302 of the present embodiment moves up and down substantially in the vertical direction with respect to the apparatus body 40 as viewed from the front side of the image forming system 1S in
The discharge portions 300A and 300B are each provided with a sheet surface detection sensor 305c serving as a detection portion for detecting a sheet stacking height, which is the upper surface position of sheets stacked on the tray 302. The sheet surface detection sensor 305c is configured such that the output signal thereof changes in accordance with the presence or absence of a sheet at a predetermined detection height. For example, a photoelectric sensor of a transmission type utilizing laser light passing through a space above the tray 302 in the X direction at a detection height can be used as the sheet surface detection sensor 305c. In addition, the discharge portions 300A and 300B are each provided with a sheet presence/absence sensor 302f for detecting the presence or absence of a sheet on the tray 302. The sheet presence/absence sensor 302f is configured such that the output signal thereof changes in accordance with whether or not a sheet is present at a detection position on the tray 302. For example, as the sheet presence/absence sensor 302f, a flag member illustrated in
A controller of the post-processing apparatus 4 controls the lifting mechanism 330, which will be described later, on the basis of the detection results of the sheet surface detection sensors 305c and the sheet presence/absence sensors 302f, and thus controls the height of the trays 302 of the discharge portions 300A and 300B. Specifically, in the case where the detection result of a sheet presence/absence sensor 302f indicates that no sheet is present on a tray 302, the tray 302 is maintained at a predetermined home position. When sheets are discharged by the discharging/reversing rollers 24 or the bundle discharge rollers 36 and stacked on the tray 302, the stacking height of sheets on the tray 302 increases. Then, each time the detection result of the sheet surface detection sensor 305c indicates that a sheet is present at a predetermined detection height, the lifting mechanism 330 is driven to lower the tray 302 by a predetermined amount in an A2 direction or a B2 direction.
In the case where the detection result of the sheet surface detection sensor 305c indicates that the sheets have been removed from the tray 302, the lifting mechanism 330 is driven to lift the tray 302 in an A1 direction or a B1 direction to return to the home position. In addition, in the case where it is determined that the tray 302 is full, for example, in the case where the sheet surface detection sensor 305c has detected a sheet in a state in which the tray 302 is at the lowest position within the lifting/lowering range thereof, the controller determines that it is impossible to discharge a sheet and stops the image forming operation.
According to such lifting/lowering control, in the discharge portions 300A and 300B, usually a distance in the Z direction in which a sheet discharged from the discharging/reversing rollers 24 or the bundle discharge rollers 36 falls onto the upper surface of a sheet on the tray 302 falls within a certain range. This suppresses falling of a sheet from the tray 302 and extreme misalignment of sheets, and thus contributes to maintaining a stable stacking state even in the case where the amount of stacked sheets is large.
A discharge portion 300 serving as a sheet stacking apparatus according to the first embodiment will be described with reference to
As illustrated in
In the present embodiment, a direction in which the discharge roller pair 301 nips a sheet and delivers out the sheet is referred to as the sheet discharge direction D. In the present embodiment, the sheet discharge direction D is inclined upward in the Z direction toward a first side in the Y direction. In addition, the lifting/lowering direction of the tray 302 with respect to the apparatus body 40 is a direction intersecting with the horizontal plane, and is substantially the same as the Z direction in the present embodiment.
The tray 302 has a supporting surface 302b serving as a supporting portion that supports a sheet. At least part of the supporting surface 302b is inclined upward in the Z direction toward the far side in the Y direction with respect to the apparatus body 40, that is, to the left in
The tray 302 is coupled to the lifting mechanism 330 via a stay 303. The lifting mechanism 330 includes a lifting motor 331 serving as a drive source, and a belt drive transmission portion including a driving pulley 333, a driven pulley 334, and a lifting belt 336. The lifting belt 336 is stretched over the driving pulley 333 and the driven pulley 334 that are arranged with an interval therebetween in the Z direction. The driving pulley 333 and the driven pulley 334 are rotatably supported by the frame member of the apparatus body 40. The driving pulley 333 is driven to rotate by the lifting motor 331, and the driven pulley 334 rotates in accordance with the rotation of the lifting belt 336. In addition, the stay 303 is fixed to the lifting belt 336 via a fixing member 337.
As a result of the lifting mechanism 330 described above, the tray 302 is lifted and lowered in accordance with the rotation of the lifting motor 331. The movement direction of the tray 302, that is, whether the tray 302 is lifted or lowered is determined in accordance with the rotation direction of the lifting motor 331, the movement amount of the tray 302 is determined in accordance with the rotation amount of the lifting motor 331, and the movement speed of the tray 302 is determined in accordance with the rotation speed of the lifting motor 331. Therefore, the controller of the post-processing apparatus 4 can control the lifting/lowering operation of the tray 302 by controlling the lifting motor 331.
To be noted, although the lifting mechanism 330 of a belt type has been described as an example of a lifting unit in the present embodiment, a different lifting unit may be used. For example, a configuration in which a motor and a pinion that is driven by the motor are disposed in the tray 302, the pinion is engaged with a rack provided in the apparatus body 40, and the tray 302 moves on the rack to ascend and descend may be employed. In addition, the lifting/lowering direction of the tray 302 by the lifting unit may be inclined with respect to the Z direction.
The side wall 305 of the apparatus body 40 includes a stacking wall 305g capable of abutting the trailing end of sheets stacked on the tray 302, that is, the upstream end of the sheets in the sheet discharge direction D, and frame portions 305f respectively provided on two sides of the stacking wall 305g in the X direction. The stacking wall 305g mainly extends in the lifting/lowering direction of the tray 302 (i.e., the Z direction) and the sheet width direction (i.e., the X direction). The frame portions 305f are preferably members rigid enough to support the weight of the lifting mechanism 330, the tray 302, and sheets of the maximum stacking amount on the tray 302, such as members having L shapes as viewed in the Z direction.
The stacking wall 305g is fixed to the frame member of the apparatus body 40, and does not move even in the case where the tray 302 is lifted or lowered. That is, the stacking wall 305g functions as a first abutting portion or first abutting member of the present embodiment that is capable of abutting or coming into contact with the trailing end of the sheets stacked on the stacking portion. However, there is no problem in making the stacking wall 305g movable not in accordance with the lifting and lowering of the tray 302, for example, by making the stacking wall 305g openable and closable or attachable to and detachable from the frame portions 305f for access to the inside of the apparatus body 40.
The stacking wall 305g includes a plurality of ribs 305b projecting to the first side in the Y direction, that is, to the downstream side in the sheet discharge direction D from a base surface extending in the X direction and the Z direction. The ribs 305b each extend in approximately the Z direction along the lifting/lowering direction of the tray 302. Ridge portions of the ribs 305b function as a contact portion or a first contact surface that comes into contact with the trailing end of the sheets stacked on the tray 302.
Slide Walls
As illustrated in
The two slide walls 306 have substantially the same configuration except that the position thereof in the X direction is different. That is, the slide walls 306 each include a contact portion 306b serving as a second contact surface, which is a portion that comes into contact with the trailing end of the sheets stacked on the tray 302, and a pressed portion 306a and an abutting surface 306c related to position control of the slide wall 306.
At least part of the contact portion 306b projects toward the first side in the Y direction with respect to the ribs 305b of the stacking wall 305g serving as a first contact surface, that is, toward the downstream side in the sheet discharge direction D. Specifically, as illustrated in an enlarged portion of
At least part of a surface of each of the slide walls 306 opposite to the contact portion 306b is engaged with a guide groove 305s illustrated in
As schematically illustrated in
The stacking wall 305g includes abutted portions 305a that the abutting surfaces 306c of the slide walls 306 abut. The abutted portions 305a function as positioning portions that position the slide walls 306 against the urging force of the spring members 307 by abutting the abutting surfaces 306c of the slide walls 306. In the description below, the positions of the slide walls 306 positioned by the abutted portions 305a will be referred to as initial positions or predetermined positions of the slide walls 306.
In addition, as illustrated in
In the description below, the position of the tray 302 when the pressing portion 302a of the tray 302 first abuts the pressed portions 306a of the slide walls 306 in the case where the tray 302 is lowered from the home position will be referred to as an accompanying movement starting position of the tray 302. In other words, the accompanying movement starting position is a position of the tray 302 in the lifting/lowering direction serving as a boundary between a state in which the slide walls 306 move in accordance with the lifting and lowering of the tray 302 (i.e., state in which the slide walls 306 move accompanying or following the tray 302) and a state in which the slide walls 306 do not move in accordance with the lifting and lowering of the tray 302. The home position of the tray 302 serves as a first position of the present embodiment and the accompanying movement starting position of the tray 302 serves as a second position of the present embodiment.
To be noted, the lower limit position of the lifting/lowering range of the tray 302 is below the accompanying movement starting position in the Z direction. The lengths of the guide grooves 305s and the like that define the movement range of the slide walls 306 are preferably set such that the slide walls 306 move in accordance with the tray 302 while the tray 302 is lifted and lowered between the accompanying movement starting position and the lower limit position. That is, by setting enough lengths for the guide grooves 305s defined in the side wall 305, the slide walls 306 can be caused to move in accordance with the tray 302 in a desired part of the lifting/lowering range of the tray 302. In addition, the upper limit position of the lifting/lowering range of the tray 302 may coincide with the home position, and for example, may be above the home position.
Next, the motion of the slide walls 306 will be described with reference to
Here, when the tray 302 is lowered from the home position of
Here, the height to which the contact portions 306b of the slide walls 306 project upward with respect to the supporting surface 302b of the tray 302 in a state in which the tray 302 is in the accompanying movement starting position of
When the tray is lowered to a position below the accompanying movement starting position, the slide walls 306 slide downward in accordance with the tray 302. Therefore, among the sheet bundle supported on the tray 302, the trailing end of sheets at the wall surface height M1 of the slide walls 306 and below are held by the contact portions 306b of the slide walls 306, and moves without rubbing the ribs 305b of the stacking wall 305g. Therefore, the occurrence of noises and damage to the trailing end of the sheets caused by rubbing the ribs 305b can be suppressed for sheets up to the wall surface height M1 of the slide walls 306.
Incidentally, there is a possibility that the trailing end of sheets positioned higher than the wall surface height M1 of the slide walls 306 rubs the ribs 305b of the stacking wall 305g as the tray 302 is lowered. However, the magnitude of force (e.g., F1 and F2 in
This can be explained as follows.
As described above, it can be seen that sheets stacked to a position higher than the wall surface height M1 of the slide walls 306 come into contact with the stacking wall 305g by a force smaller than a force by which sheets stacked to a position equal to or lower than the wall surface height M1 abut the slide walls 306. The former force corresponds to the force F2, and the latter corresponds to the force F1. That is, it can be seen that lower layers of the sheet bundle of sheets of a relatively large amount staked on the tray 302 strongly rub sheets, the stacking wall 305g, and so forth and serve as a main cause of noises when the tray 302 is lowered. Therefore, noises caused by vibration of sheets and damage to the trailing end of sheets are not likely to occur even if the trailing end of sheets stacked to a position higher than the wall surface height M1 of the slide walls 306 rub the ribs 305b of the stacking wall 305g in accordance with the lowering of the tray 302.
According to the present embodiment, in the case where the tray 302 is lowered through the accompanying movement starting position, the slide walls 306 move in accordance with the tray 302 when the tray 302 is positioned below the accompanying movement starting position. In other words, in the case where a stacking portion is lowered from a first position through a second position below the first position, a second abutting portion or a second abutting member of the present embodiment is positioned at a predetermined position and does not move down in accordance with the stacking portion when the stacking portion is lowered from the first position to the second position (i.e., before the stacking portion passes the second position), and moves down from the predetermined position in accordance with the stacking portion when the stacking portion is lowered beyond the second position.
As a result of this, occurrence of noises and the like caused by rubbing in a state in which a sheet bundle of a relatively large amount is stacked on the tray 302, in which issues such as noises and damage to sheets are likely to be caused by the trailing end of the sheets rubbing a fixed abutting portion such as the stacking wall 305g. Therefore, occurrence of noises and the like caused by the sheets rubbing the abutting portion can be effectively suppressed by a configuration in which the slide walls 306 are configured to move in accordance with the tray 302 in part of a lifting/lowering range of the tray 302.
In addition, since the slide walls 306 of the present embodiment are members slidably supported by the stacking wall 305g, the occurrence of noises caused by rubbing by the sheets can be suppressed by a simpler configuration than in the case of, for example, using a belt member stretched over a plurality of pulleys.
Although the two slide walls 306 having elongated plate shapes extending in the Z direction are used in the present embodiment, the shape and number of the second abutting portions or second abutting members may be arbitrarily changed. For example, the slide walls 306 of the present embodiment may be connected in the X direction and be integrated to have a single wide plate shape. In addition, freely rotatable roller members may be attached to the slide walls 306 such that the slide walls 306 come into contact with the wall surface of the guide grooves 305s via the roller members.
The discharge portion 300 serving as a sheet stacking apparatus according to a second embodiment will be described with reference to
As illustrated in
As illustrated in
The configuration of the first slide walls 316 is substantially the same as the slide walls 306 of the first embodiment. That is, the first slide walls 316 are slidable in approximately the Z direction along the guide grooves 305s provided in the stacking wall 305g. Abutting surfaces 316c of the first slide walls 316 are caused to abut the abutted portions 305a of the stacking wall 305g by the urging force of the spring members 307 illustrated in
The configuration of the second slide walls 317 is substantially the same as that of the first slide walls 316 except that the setting of the accompanying movement starting position is different from that of the first slide walls 316. That is, the second slide walls 317 each include a contact portion 317b that comes into contact with the trailing end of the sheets stacked on the tray 302, a pressed portion 317a that is a protrusion pressed by the pressing portion 302a of the tray 302, and an abutting surface that abuts the abutted portion 305a of the stacking wall 305g. The second slide walls 317 are slidable in approximately the Z direction along the guide grooves 305s provided in the stacking wall 305g.
The second slide walls 317 are positioned at initial positions illustrated in
To be noted, contact portions 316b, which are parts of the first slide walls 316 serving as second abutting portions where the first slide walls 316 come into contact with the trailing end of the sheets and which serve as second contact surfaces, project further toward the first side in the Y direction, that is, toward the downstream side in the sheet discharge direction D than contact portions 317b, which are parts of the second slide walls 317 serving as third abutting portions where the second slide walls 317 come into contact with the trailing end of the sheets and which serve as third contact surfaces. In addition, the contact portions 317b of the second slide walls 317 project further toward the first side in the Y direction than the ribs 305b of the stacking wall 305g serving as a third contact surface.
The home position of the tray 302 serves as a first position of the present embodiment, the first accompanying movement starting position for the first slide walls 316 serves as a second position of the present embodiment, and the second accompanying movement starting position for the second slide walls 317 serves as a third position of the present embodiment.
Here, the position of the tray 302 where the second slide walls 317 start moving in accordance with the tray 302, that is, the second accompanying movement starting position, is set to be lower than the position of the tray 302 where the first slide walls 316 start moving in accordance with the tray 302, that is, the first accompanying movement starting position, in the case where the tray 302 is lowered from the home position. Specifically, the pressed portions 317a of the second slide walls 317 are configured to be positioned below the pressed portions 316a of the first slide walls 316 in a state in which the first slide walls 316 and the second slide walls 317 are respectively at the initial positions thereof. As a result of this configuration, in the lowering of the tray 302, the pressing portion 302a abuts the pressed portions 317a of the second slide walls 317 at a timing later than the timing at which the pressing portion 302a abuts the pressed portions 316a of the first slide walls 316 as will be described later.
The motions of the first slide walls 316 and the second slide walls 317 will be described with reference to
While the tray 302 is lowered from the home position of
Here, the height to which the contact portions 316b of the first slide walls 316 project upward with respect to the supporting surface 302b of the tray 302 in a state in which the tray 302 is in the first accompanying movement starting position of
To be noted, in the case where the tray 302 is lifted and lowered in a region between the first accompanying movement starting position and the second accompanying movement starting position, the trailing end of sheets stacked higher than the wall surface height M2 of the first slide walls 316 rubs the ribs 305b of the stacking wall 305g. However, as described above, the force by which sheets higher in the sheet bundle stacked on the tray 302 abut the stacking wall 305g is smaller than the force by which lower sheets abut the first slide walls 316 as illustrated in
In addition, since the first slide walls 316 project further than the second slide walls 317, sheets up to the wall surface height M2 of the first slide walls 316 mainly do not rub the second slide walls 317 while the tray 302 is lifted and lowered between the first accompanying movement starting position and the second accompanying movement starting position.
Here, the height to which the contact portions 317b of the second slide walls 317 project upward with respect to the supporting surface 302b of the tray 302 in a state in which the tray 302 is in the second accompanying movement starting position of
To be noted, in the case where the tray 302 is lifted and lowered in a region below the second accompanying movement starting position, the trailing end of sheets stacked higher than the wall surface height M3 of the second slide walls 317 rubs the ribs 305b of the stacking wall 305g. However, the force by which sheets stacked higher in the sheet bundle stacked on the tray 302 abut the stacking wall 305g is smaller than the force by which lower sheets abut the first slide walls 316 or the second slide walls 317. Therefore, issues such as noises are not likely to occur even in the case where the trailing end of the sheets stacked higher than the wall surface height M3 of the second slide walls 317 rubs the ribs 305b of the stacking wall 305g due to the lifting and lowering of the tray 302.
As described above, in the present embodiment, the second slide walls 317 serving as third abutting portions or third abutting members capable of moving in accordance with the lowering of the stacking portion are provided in addition to the first slide walls 316 serving as second abutting portions or second abutting members. As a result of this, occurrence of noises and the like caused by the rubbing by the sheets can be suppressed similarly to the first embodiment.
Further, according to the present embodiment, the performance of suppressing the occurrence of noises and the like caused by rubbing by the sheets can be improved in both cases where the amount of sheets stacked on the tray 302 is small and large. For example, if it is attempted to increase the amount of sheets that do not come into contact with the stacking wall 305g by increasing the wall surface height M1 of the slide walls 306 in the configuration of the first embodiment, the amount of sheets stacked before the tray 302 reaches the accompanying movement starting position for the slide walls 306 increases. It can be considered that as a result of this, issues such as noises caused by the rubbing between the sheets and the slide walls 306 occur before the slide walls 306 start moving in accordance with the tray 302. In contrast, if the wall surface height M1 of the slide walls 306 is reduced, it can be considered that the proportion of the sheets stacked higher than the wall surface height M1 increases, and issues such as noises caused by the rubbing between the sheets and the stacking wall 305g occur.
In contrast, according to the present embodiment, such inconvenience can be avoided by using in combination the two kinds of slide walls 316 and 317 having different standards for the sheet stacking amount on the tray 302 at the time of start of the accompanying movement with the tray 302. That is, since the second slide walls 317 that abut the trailing end of sheets in a region above the first slide walls 316 are provided, the occurrence of noises and the like caused by the rubbing by the sheets can be suppressed more than in the case where only the first slide walls 316 are provided even in a state in which a large amount of sheets are stacked on the tray 302. In addition, in the case where the amount of sheets stacked on the tray 302 is relatively small, the first slide walls 316 start moving in accordance with the tray 302 while the second slide walls 317 are still in the initial positions, and thus the occurrence of noises and the like caused by the rubbing by the sheets can be suppressed.
To be noted, the configuration in which the first accompanying movement starting position and the second accompanying movement starting position of the tray 302 are varied is not limited to the configuration described above in which the positions of the pressed portions 316a and 317a in the Z direction are varied. For example, forming the pressing portion 302a of the tray 302 in a shape whose height in the Z direction is different between a region for pressing the pressed portions 316a of the first slide walls 316 and a region for pressing the pressed portions 317a of the second slide walls 317 can be considered.
In addition, although a configuration in which the second slide walls 317 are directly pressed by the tray 302 and thus move in accordance with the tray 302 is employed in the present embodiment, a configuration in which the second slide walls 317 move in accordance with the lowering of the tray 302 via the first slide walls 316 may be employed. For example, the pressed portions 317a of the second slide walls 317 may be formed in shapes projecting in the X direction to be pressed by the lower surfaces of the pressed portions 316a of the first slide walls 316. In addition, although two kinds of slide walls having different wall surface heights are used in the present embodiment, three or more kinds of slide walls having different wall surface heights may be used.
The discharge portion 300 serving as a sheet stacking apparatus according to a third embodiment will be described with reference to
Two slide walls 326 are provided at positions symmetrical to each other with respect to the center position of the discharge portion 300 in the X direction. The slide walls 326 each include a contact portion 326b that comes into contact with the trailing end of sheets stacked on the tray 302, a pressed portion 326a pressed by the pressing portion 302a of the tray 302 illustrated in
Here, the guide grooves 325s serving as second guide portions each extend in a curved shape as viewed from the downstream side in the sheet discharge direction D. In the illustrated example, the guide grooves 325s are defined as arcs extending in the up-down direction as viewed from the downstream side in the sheet discharge direction D. The slide walls 326 are each engaged with the guide groove 325s in at least two positions in the longitudinal direction of the guide groove 325s. Therefore, the slide walls 326 are supported by the stacking wall 305g in a slidable state in sliding directions along the longitudinal directions of the guide grooves 325s extending in curved shapes. In addition, the slide walls 326 are each urged upward by an urging force of a spring force substantially the same as the spring member 307 of the first embodiment illustrated in
When the tray 302 is positioned in the home position, the slide walls 326 are positioned in the initial positions thereof by the urging force of the spring members. At this time, the pressing portion 302a of the tray 302 is at a position separated upward from the pressed portions 326a of the slide walls 326. While the tray 302 is lowered from the home position to the accompanying movement starting position for the slide walls 326, the slide walls 326 are still in the initial positions. At this time, the sheets on the tray 302 rub the contact portions 326b of the slide walls 326 and the ribs 305b of the stacking wall 305g. However, the amount of sheets stacked on the tray 302 is relatively small at this stage, thus the upstream force in the sheet discharge direction D acting on the sheets due to the inclination of the tray 302 is relatively small, and therefore issues such as noises caused by rubbing by the sheets are not likely to occur.
When the tray 302 reaches the accompanying movement starting position for the slide walls 326, the pressing portion 302a of the tray 302 abuts the pressed portions 326a of the slide walls 326, and thus a state in which the slide walls 326 move in accordance with the lowering of the tray 302 is taken. Then, as illustrated in
Here, the height to which the contact portions 326b of the slide walls 326 project upward with respect to the supporting surface 302b of the tray 302 in a state in which the tray 302 is in the accompanying movement starting position for the slide walls 326 will be referred to as a wall surface height M4 of the slide walls 326. When the tray 302 is lowered in a region below the accompanying movement starting position, the slide walls 326 slide downward in accordance with the tray 302. Therefore, among the sheet bundle supported on the tray 302, the trailing end of sheets at the wall surface height M4 of the slide walls 326 and below are held by the contact portions 326b of the slide walls 326, and moves without rubbing the ribs 305b of the stacking wall 305g. Therefore, the occurrence of noises and damage to the trailing end of the sheets caused by rubbing the ribs 305b of the stacking wall 305g can be suppressed for sheets up to the wall surface height M4 of the slide walls 326. In addition, although the sheets stacked higher than the wall surface height M4 rub the ribs 305b in accordance with the lifting and lowering of the tray 302, since the force by which these sheets abut the ribs 305b is relatively small, issues such as noises caused by the rubbing are not likely to occur.
As described above, the occurrence of issues such as noises caused by the rubbing by the sheets derived from the lifting and lowering of the tray 302 can be reduced similarly to the first embodiment also in the case where a configuration in which the movement trajectories of the slide walls 326 are curved is employed.
The configurations described above in the first to third embodiments are merely examples. For example, the lengths of the slide walls 306, 316, 317, and 326 serving as second abutting portions, second abutting members, third abutting portions, and third abutting members in the lifting/lowering direction of the tray 302, and the range in which the slide walls move in accordance with the tray 302 may be changed.
In addition, although a configuration in which part of the tray 302 abuts and presses the slide walls downward and thus the slide walls move in accordance with the lifting and lowering of the tray 302 has been described in the embodiments described above, the accompanying movement of the tray 302 and the slide walls may be realized by a different engagement method. For example, providing a mechanism in which the tray 302 and the slide walls are relatively unmovably locked to each other in the lifting/lowering direction of the tray 302 when the tray 302 abuts the slide walls may be considered. Examples of such a locking mechanism include a toggle mechanism and a snap-fit.
In addition, although the slide walls that slide with respect to the stacking wall 305g have been described as examples of second abutting portions or second abutting members in the embodiments described above, for example, members that pivot or swing about a pivot shaft may be used as the second abutting portions or second abutting members. In this case, a configuration in which contact portions are provided on outer peripheral portions away from the pivot shaft, and the contact portions move up and down in accordance with the lifting and lowering of the tray 302 is employed.
Although a sheet stacking apparatus or a sheet discharge apparatus provided in a sheet processing apparatus constituting a part of an image forming system has been described in the embodiments described above, the present technique is applicable to a sheet stacking apparatus or a sheet discharge apparatus in a different apparatus that handles a sheet. Examples of this include a sheet stacking apparatus or a sheet discharge apparatus onto which sheets subjected to image formation are discharged and stacked from an image forming apparatus body in an image forming system not including a sheet processing apparatus.
While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the disclosure 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. 2020-066671, filed on Apr. 2, 2020, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2020-066671 | Apr 2020 | JP | national |
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| Number | Date | Country | |
|---|---|---|---|
| 20210309480 A1 | Oct 2021 | US |
