Abstract: A printer exit tray assembly attachable to a printer housing and a computer printer including a printed paper exit tray assembly. The exit tray assembly has an exit tray and a pair of sheet supports attached to the exit tray. The exit tray is movable between a use position and a collapsed position. The exit tray is positioned generally horizontally in the use position. The exit tray projects horizontally further from the printer housing in the use position than in the collapsed position. When the exit tray is in the use position the supports are pivotable, with respect to the exit tray, between a support position for supporting a printed sheet above the exit tray and a release position for releasing the printed sheet to the exit tray.

Abstract: A sheet sorting device for a sheet discharging apparatus which has a sheet discharging tray which receives discharged sheets when the sheet sorting device is not attached to the sheet discharging tray. The sheet sorting device includes a movable tray which is configured to receive sheets discharged from the sheet discharging apparatus and configured to reciprocate in a reciprocating direction substantially perpendicular to a sheet conveying direction of the sheet discharging apparatus by a predetermined stroke necessary for sorting sheets. The sheets are sorted by reciprocating the movable tray in the reciprocating direction. The sheet sorting device is configured to detachably attached to the sheet discharging tray.

Abstract: A storage apparatus has a card-accommodating, vertically upright stack-storage cassette (1) and a card-input, -reading and control unit (3) arranged adjacent to the top cassette-border region (4). The stack-storage cassette (1) has a vertically running storage opening (5) arranged in a cassette side. The storage apparatus also has a lift unit (7) which can be displaced vertically in said opening (5) and has a lift housing (19a, 19b). The lift unit (7), for its part, has a depositing plate (9) for the cards, which comes to rest in the store interior (10). The lift unit can be removed in the lowermost region of the cassette (1), to be inserted into the cassette (1) at the top and, acting on the opening borders, to be displaced vertically, i.e. lowered, in each case preferably by the distance of a height over which a group of cards is deposited, in order for the cards to be deposited satisfactorily.

Abstract: The present invention relates to a piling rack for flat parcels which is open on one side for withdrawing piled parcels. The rack has a bottom (4) as well as an impact wall (7) inclined outwardly and turning inwardly relative to the cutting edge, wherein a side wall (5) is provided for orienting the piling bottom as well as the piling direction. The parcels are inserted through an adequate opening (1) towards the bottom. The piling bottom (4) is inclined relative to the parcel orientation upon insertion into the piling rack and relative to the impact wall (7) and the side wall (5). The piling rack comprises a lid (8) which is mounted and shaped so that its inner outline extends at least from a curved portion towards the piling bottom (4) below the upper limit of the parcel trajectory.

Abstract: A sheet feeding device for an image forming apparatus including a main body case includes a sheet feeding tray that is rotatably supported by the main body case so as to be placed at at least a closed position where a sheet feeding inlet is closed by the sheet feeding tray and an open position where the sheet feeding inlet is opened for feeding the sheet into the main body case, a sheet feeding member that feeds the sheet on the sheet feeding tray into the main body case, and an arm including a base end part and a tip end part. The tip end part of the arm includes an arm engagement part that is engaged with an engagement part for the open position provided to the main body case so as to place the sheet feeding tray at the open position.

Abstract: A paddle urging system for use in a stacking bin having a constant force spring to provide an urging force to a paddle for supporting a stack of mailpieces. As mailpieces are accumulated into the stack, they push the stack against the paddle. A brake/clutch system is used to provide an additional drag to the paddle to resist against this movement of the paddle. The brake/clutch system is adjustable so that heavy mailpieces are supported more effectively, whereas lightweight mailpieces encounter less resistant force when they are accumulated into the stack.

Abstract: A sheet feeder has a sheet tray 10 that rotates around a shaft 12 perpendicularly to a sheet mounting surface, and is accommodated in a sheet feeder body. The sheet feeder has a sheet tray 11 disposed to rotate around the shaft 12 and connected to the tray 10 so that the tray 11 partly overlaps with the tray 10, and is accommodated in the sheet feeder body, and an abutting rib 13 for forwardly pushing the tray 11 when the sheet trays 10 and 11 are connected together. A part of the sheet tray 10 overlapping with the sheet tray 11, has a thin portion 10a. A part of the tray 11, overlapping with the sheet tray 10, has a thin portion 11a. The thin portions 10a and 11a butt against each other in an overlapping portion where the sheet trays 10 and 11 overlap with each other.

Abstract: A device for separating groups of sheets may be used on an apparatus for forming and banding groups of sheets comprising at least one track to feed the individual sheets to a pick up roller for the individual sheets arriving and to transfer said sheets to a stacking channel, extending along a stacking axis, where the sheets are placed on top of one another in stacks which may be preset and banded, one after another. The device comprises a partial support element for the sheets transferred, which operates between the roller and the channel and is mobile, by means synchronized with the roller, between an operating separation position, in which the element is partially inside the dimensions of the roller, intercepting a portion of a first sheet in a stack to be formed, and a release position, in which the element is outside the dimensions of the roller and close to the mouth of the channel, partially supporting a corresponding presettable stack of sheets fed from the roller.

Abstract: A stacker on which a recording medium discharged from an outlet of a recoding apparatus is placed, is movable between a first position for closing the outlet and a second position for opening the outlet. A sheet receiving face receives the discharged recording medium, while being a first form when the stacker is placed in the first position, and being a second form when the stacker is placed in the second position. The sheet receiving face is formed with at least one aperture in an upstream end portion with regard to a sheet discharging direction. A holder supports the upstream end portion of the sheet receiving face. The holder includes at least one retainer engaged with the aperture so as to prevent the sheet receiving face from deforming upward.

Abstract: A single tray is used to collate the printed papers from a printer. The tray is moved to different positions to receive the printed papers. Thus, the printed papers are collated into different stacks. The movement of the tray can be linear or curvilinear. The circular movement can collate the printed papers into more than two stacks.

Abstract: In a method and a device for forming groups of sheets consisting of one or of a plurality of sheets, a predetermined number of sheets is first supplied to a first position in a collecting station so as to form a first group of sheets. As soon as the first group of sheets has been formed, it is moved from the first position to a second position in the collecting station, and then a predetermined number of sheets is moved to the first position in the collecting station so as to form a second group of sheets.

Abstract: A fulcrum shaft 61 and a recessed sheet member 64, which together constitute an ejected paper receiving unit that is rotatable force forward and backward within a range extending from a front receiving position and a rear receiving position. When an operator rotates the ejected paper receiving unit 6 forward and sets it at the front receiving position, a print sheet that is ejected by a paper ejection unit 4 is accepted while sliding forward along the sheet member 64. And when the operator rotates the ejected paper receiving unit 6 to the rear and sets it at the rear receiving position, a print sheet ejected by the paper ejection unit 4 is accepted while sliding to the rear along the sheet member 64.

Abstract: An apparatus for handling paper sheets and the like has a mechanism for discharging the paper sheets. The mechanism is provided with a scraper for scraping the paper sheets having wound around a wheel from the wheel. The scraper has a tip end and an opposite end that is rotatably supported in a direction close to or away from the wheel so that the tip end can maintain contact with an outer peripheral surface of the wound paper sheets. The scraper includes a first scraper section and a second scraper section. The first scraper section is rotatably supported in the direction close to or away from the wheel, and is urged toward an outer peripheral surface of the wheel. The second scraper section is rotatably supported on the first scraper section in the direction close to or away from the wheel, and is urged in a direction in which a tip end of the second scraper section rotates toward the outer peripheral surface of the wound paper sheets.

Abstract: A medium stacker is disclosed, which has a structure that effectively processes load externally applied to a stacker tray so as to prevent damage of the medium stacker and an external object from occurring and increases the ascending range of a stacker tray without change of a power transmission structure. The medium stacker includes a basic module frame fixed to a medium unit of a main body of an output device, a stacker tray fixed to the basic module frame to enable the ascending operation, on which ejected papers are stacked, a first guide means provided in the basic module frame, guiding the ascending operation of the stacker tray, a lifting belt ascending the stacker tray along the first guide means, and a belt driving pulley fixed to the lifting belt. The lifting belt includes a first part moving along the belt driving pulley, having one end fixed to the stacker tray, and a second part of an elastic member which is not moving along the belt driving pulley, having one end fixed to the basic module frame.

Abstract: Sheets (57) exit printer (1) into finisher (3) through corrugation rollers (13a-13d, 15a, 15b, 15aa, 15bb) encounter actuator tab (9a) to thereby rotate actuator (9) upward. Bails (11a-11b) are engaged by this and rotate upward. Each bail has a wing (11d, 11dd, 11e), which prevents curling. When the sheet is exited, gravity acting on the sheet and the actuator tab causes the sheet to drop. The bails also drop under gravity. The sheet is positioned to drop flat and near the exit, as intended for the finisher to form stacks of sheets.

Abstract: To provide a storing device for paper sheets capable of increasing the number of banknotes that can be stored without increasing the dimension in a back and forth direction of a device main body. A second plate is moved in a direction substantially perpendicular to a face of a paper sheet by moving other ends of arms substantially parallel to the second plate, and thus drive force of a drive means is applied to the other ends of the arms, thereby moving the other ends of the arms substantially parallel to the second plate. Consequently, a space in the direction substantially perpendicular to the face, which is required for the arm movement, can be reduced as compared with the case in which the center part of the arm is driven.

Abstract: A device for removing proof sheets and reject sheets from a side of a delivery of a sheet-processing machine includes a collecting container for accommodating removed sheets therein in an operating position of the container, the container being displaceable into a park position wherein it is located above the delivery; and a sheet-processing machine, in particular, including the sheet-removing device.

Abstract: A sheet discharge apparatus of the present invention is equipped with a discharge device for discharging a sheet from an image forming apparatus, a storage device for storing the sheet discharged from the discharge device, an elevator device for raising and lowering the storage device relative to the discharge device, a position detection device for detecting a surface of the uppermost sheet stored in the storage device or a surface of the storage device to stack the sheet, a reception device for receiving a signal indicating a transport status in the image forming apparatus, and a control device for temporarily stopping the discharge device after the transported sheet is discharged to the storage means by the discharge means when the position detection device detects the uppermost surface of the uppermost sheet stored in the storage device or the surface of the storage means to stack the sheet is away from a predetermined position and the reception device detects the sheet transported in the image forming ap

Abstract: A shingling nip roll is added between an infeed conveyor and a reciprocating table. The nip roll slows the speed of the sheets thereby reducing bruising and buckling as sheets are ejected to the table. Further, the trailing end of a dropped sheet is overlapped by a leading end of the next upstream sheet which assists in maintaining control of the dropped sheet as it drops onto the reciprocating table.

Abstract: A configuration controls the height and the inclination of a stacking tray according to the number of sheets discharged and controls the height and the inclination of a stacking tray when discharging sheets and when discharging sheet bundles to improve alignment of discharged sheets and the transporting characteristics. When discharging a sheet bundle, a stacking tray is lowered and when it reaches its home position, the aforementioned stacking tray is stopped. When discharging a sheet, the system determines whether it is the first sheet of a plurality of sheets in a bundle. For the first sheet, a timer is set to a predetermined time from raising to stopping the aforementioned stacking tray (using a pulse count value) and the aforementioned stacking tray is raised. After the set time is up, the stacking tray is stopped at a preset position.

Abstract: Disclosed are a sheet-shaped medium aligning apparatus, an image forming apparatus and a sheet-shaped medium after-treatment apparatus. An arranging means is moved from a position for arranging sheet-shaped mediums on a sheet piling means to a position to be received in a body, to be receive-able and is moved from the receiving position to the arranging position, so that in taking out the sheet-shaped mediums, an injury of hands or destruction of arranging means due to interference of hands of an operator with the arranging member can be prevented.

Abstract: A single tray is used to collate the printed papers from a printer. The tray is moved to different positions to receive the printed papers. Thus, the printed papers are collated into different stacks. The movement of the tray can be linear or curvilinear. The circular movement can collate the printed papers into more than two stacks.

Abstract: An apparatus for stacking a stream of moving sheet-like material such as, for example, mailpieces is described.

Abstract: A sheet accumulator has a circular paper path and a compact design. Individual sheets of paper moving along a main linear path are diverted into the accumulator one by one, and each sheet enters a gripper having jaws that grip the sheets of paper. The gripper jaws pull the sheets along the circular paper path until the gripper returns to a home location, at which point the gripper stops, opens, accepts another sheet, closes, and makes another rotation. When the accumulation is complete, the gripper jaws open to release an accumulated stack of sheets, and a roller is then engaged to exit the sheets out of the accumulator and into the main linear paper path.

Abstract: A foldable tray is angularly displaceably supported at an end portion of a sheet tray of a printer body so as to be angularly displaceable about a supporting shaft, which foldable tray is capable of being folded onto an upper surface side of the sheet tray and is angularly displaced downwardly from the sheet stacking position when a force which exceeds the maximum loading weight of sheets is applied to the foldable tray. Further, the sheet tray comprises a stopper for holding the foldable tray at a sheet stacking position and at a downwardly displaced position by abutting the foldable tray against the stopper.

Abstract: A sheet receiving apparatus includes a tray swingably supported by an apparatus main body so that it is selectively put to a state of use, in which sheets can be loaded thereon, and to a state of accommodation and a regulation unit abutted against the tray for regulating the swing motion thereof to keep the state of accommodation, wherein the center of swing of the tray is arranged movably and the tray can be shifted to the state of use by releasing the swing thereof regulated by the regulation unit by moving the center of swing thereof. With this arrangement, the sheet receiving apparatus can be highly reliably arranged without an increase in a cost and has no possibility of the deformation and breakage of the parts thereof.

Abstract: A device for enabling access to an interior of an apparatus, with means for unlocking and swinging an upper apparatus housing part supporting a sheet stacking container clear out of a sheet dispensing area of the apparatus that has a sheet discharge unit and is freely accessible for sheet removal.

Abstract: A single tray is used to collate the printed papers from a printer. The tray is moved to different positions to receive the printed papers. Thus, the printed papers are collated into different stacks. The movement of the tray can be linear or curvilinear. The circular movement can collate the printed papers into more than two stacks.

Abstract: A drop table is used for accumulating a desired number of sheets of items in a bundle and then dropping the bundle onto a conveyor belt. The drop table has a plurality of rods acting as a floor in a collection box. When the drop table receives a signal from a sheet feeder that the number of items desired is in the bundle the rods are withdrawn from beneath the collection box and the bundle drops to a conveyor belt. The rods are then moved back into position for receiving more sheets to form another bundle and the drop table signals the sheet feeding machine to send more sheets to the collection box. The collection box may have a vibrating jogger to align the sheets into a squared bundle on one axis and a tamping foot to align the sheets into a squared bundle on a second axis. The drop table can accumulate sheets in a squared bundle quickly without jamming and release the bundle onto a conveyor below the collection box.

Abstract: A sheet process apparatus includes a stapler for performing a stapling process on a sheet any a shift sheet discharge unit for performing shift sheet discharging. The shift sheet discharging discharges and stacks the sheets on a tray in a status that the sheet intended to be discharged is shifted from the sheet already put on the tray. A control unit causes the shift sheet discharge unit to perform shift sheet discharging when the stapling process by the stapler is not included in any of a previous-time job and a present-time job. The control unit also causes the shift sheet discharge unit to perform the shift sheet discharging when the stapling process by the stapler is not included in any of a previous-time job and a present-time job. In addition, the control unit also causes the shift sheet discharge unit to discharge the sheet without performing the shift sheet discharging when the stapling process by the stapler is included in at least one of the previous-time job and the present-time job.

Abstract: A tray member incorporated in a tray device is movable vertically in parallel in accordance with the thickness of sheets fed from a sheet handling system, so as to easily attach the tray device to the sheet handling system such as an image forming device, copying machine, printer and sheet post-processing apparatus for automatically stapling sheets. A driving mechanism for vertically moving the tray member is simple in structure, so that it can be incorporated compactly within the tray member. A low-power driving mechanism suffices for vertically moving only the tray member, so that the driving mechanism can be efficiently operated even with small power. The tray device has all the component elements including the driving mechanism built-in, so as to impose little structural restrictions on the sheet handling system to which the tray device is united.

Abstract: An apparatus for and method of stacking flexible articles of a non-uniform thickness involves the use of a stacking table including separately movable first and second support surfaces. An actuator moves the stacking table through a range of motion relative to a stationary cam plate. A cam follower is mechanically coupled to the second support surface and engages the cam surface when the stacking table is moved through at least part of the range of motion. When the actuator moves the stacking table and the cam follower engages the cam surface, the second surface is displaced relative to the first support surface. Preferably, the cam plate is repositionable to vary a distance by which the second support surface is displaced relative to the first support surface.

Abstract: A method and apparatus for horizontal stacking of sheets or signatures received from a web press or the like includes conveyor sections operative to convey the sheets in shingled relation from a generally horizontal conveyor path to an inclined conveyor section that progressively rotates the sheets to inclined positions such that the sheets slide downward against an edge guide. The inclined sheets then pass upwardly through a loop conveyor section at an inclined angle to vertical. The upper edge of each success sheet engages a stop mechanism after which the sheets move horizontally into a generally V-shaped trough that engages and supports two downwardly facing edges of each sheet.

Abstract: A sheet treating apparatus including a stacking tray having a stacking surface for receiving and stacking sheets thereon and a stopper portion for regulating the end portions of the sheets, a delivery rotary member for delivering the sheets to the stacking tray, an endless belt member contacting with and acting on the upper surface of the sheets on the stacking tray, and feeding the delivered sheet so as to pull the end portion thereof into the stopper portion, and a traction device for pulling a portion of the endless belt member in a predetermined direction, wherein during the feed of the sheet caused by the endless belt member, the traction device is operated in conformity with the height of the sheets stacked on the stacking tray to thereby control the contact pressure of the endless belt member against the sheets stacked on the stacking tray so as to become substantially constant.

Abstract: A printing apparatus provided with a deposition unit for printed sheets comprising a number of copy trays situated one above the other, which trays are adjustable in height independent of one another to a deposition position with respect to the sheet delivery rollers disposed at a fixed height, and to a parking position. Upon the activation of the printing apparatus by a start key provided on the printing apparatus, a control system sets the bottom copy tray into a deposition position and the other copy trays into a higher parking position. Upon the activation of the printing apparatus by a start key disposed at a distance from the printing apparatus at a workstation, the control system selectively sets one of the other copy trays into a deposition position and the bottom copy tray into a lower parking position.

Abstract: The present invention aims at providing a post-printing processor in which a user can easily find his/her print job.

Abstract: A sheet stacking device including a stacking tray for stacking and containing sheets, and a lifting and lowering device for moving the staking tray up and down. In this case, the lifting and lowering device includes a driving force converting device for changing the distance of moving the stacking tray as an input and output ratio with respect to a predetermined driving force from a driving source, and changing the elevating speed of the stacking tray according to the input and output ratio. The driving force converting device includes a suspension member for suspending the stacking tray and a winding member having a conical winding portion for winging the suspension member, and lifts and lowers the stacking tray by rotating the winding member, and the elevating speed of the stacking tray is changed according to the winding length of the suspension member, which is changed depending on the diameter difference of the winding portion.

Abstract: An apparatus for dropping paper sheets at a predetermined paper-stack position when the paper sheets are ejected from a facsimile device includes a conveyor belt which carries the paper sheets, a housing, containing the conveyer belt, which is detachably installed on the facsimile device where the paper sheets are ejected from the facsimile device such that the conveyor belt extends from a paper outlet of the facsimile device to the predetermined paper-stack position, and a driving motor, driving the conveyor belt to carry the paper sheets, which starts operating about a time when the facsimile device starts a paper-ejection operation thereof and stops operating about a time when the facsimile device stops the paper-ejection operation thereof.

Abstract: A stapling apparatus for forming a plurality of sheet bundles on a sheet tray comprises a sheet tray, a stapler, moving means, and movement controlling means. The stapler is moved upward by the moving means and the movement controlling means to the position where plural sheets placed on the sheet tray are to be stapled. Consequently, the stapling apparatus can staple the sheets in the position where the sheets are to be bound which changes upward each time the sheet bundle is formed by the stapler and form a plurality of sheet bundles on the sheet tray.

Abstract: A sheet treating apparatus includes a tray liftable and lowerable while sheets are stacked on the tray. A sheet pressing member is movable between a pressing position in which the sheets on the tray are pressed by the sheet pressing member and a retracted position. A sheet pressing member driving device retracts the sheet pressing member when the tray is lowered and for moving the sheet pressing member to the pressing position when the tray is lifted. A detecting device detects a height position of the sheets on the tray to stop lifting the tray.

Abstract: A sheet receiving/stacking device, which has a sheet stacking portion for stacking sheets, a sheet conveying portion for conveying sheets to the sheet stacking portion, and a retractable sheet guiding portion for catching the bottom surface of a sheet and then guiding the sheet to the sheet stacking portion. The sheet guiding portion is moveable between a guide position and a retracted position.

Abstract: Sheet receiving apparatus is disclosed for receiving paper sheets from a supply of printed sheets, aligning the sheets edgewise, dropping the sheets to a receiver tray through horizontally openable preliminary sheet supporting plates, the sets of sheets being either stacked in vertical alignment or horizontally offset relationship, and in one form means are provided for stapling the sets of sheets.

Abstract: A sheet handling device includes an ejection device for ejecting sheets; a stack device for stacking thereon the sheets ejected by the ejection device and having a stopper portion for supporting the ends of the sheets; a rotatable feeding member shaped like an endless belt for making contact with the sheets stacked on the stack device to pull the sheets toward the stopper portion; an aligning device for aligning the sheets on the stack device by moving the sheets in the direction orthogonal to the sheet feeding direction; a shift device for moving the endless feeding member between the acting position to act on the surface of the sheets on the stack device and the retracted position to separate from the sheet surface or to reduce the force acting on the sheet surface; and a control device for exerting control so that the endless feeding member is retracted to the retracted position during the aligning operation by the aligning device.

Abstract: A sheet-receiving device has multiple sheet receiving faces on which to receive different print jobs. The print faces are positioned in tandem with respect to each other. Sheets ejected from an apparatus are ejected onto a first of the multiple faces and remain their until moved. If another print job is to be printed, the operator may move the first print job from the first sheet receiving face to the second sheet receiving face simply by sliding the first print job to the second sheet receiving face. The first print job snaps into place, and curled edges of upper sheets in the first print job are blocked by a barrier between the first and second sheet receiving face so that sheets in the first print job do not interfere with the reception of sheets in the second print job.

Abstract: A device for separating a sheet pile during the running operation of a pile-forming sheet-processing machine includes a separator which, when an auxiliary pile carrier is pushed into a sheet pile to be separated, is movable between a rear upper edge of the sheet pile to be separated and a following sheet for a new sheet pile, for the purpose of lifting a rear lower edge of the new sheet pile at least into an effective range of a rear sheet stop; and a pile-forming sheet-processing machine and a pile-forming sheet-fed printing machine, respectively, including the separating device.

Abstract: Sheets are output by an office machine in collected form. The sheets are initially supported on their side edges by rest bars and support levers. The rest bars support the sheets on their side edges while the support levers support the sheets only in their central region. If the rest bars are moved apart, first the front and the rear end of the sheets are released while the central region is still supported by the support levers. Only upon further movement outwardly are the sheets released by the support levers.

Abstract: A cassette for receiving and storing banknotes advantageously uses a movable guide in combination with a movable actuator which each move toward the other for stripping of a banknote received in the guide and adding the stripped banknote to a stack of banknotes.

Abstract: A print media handling system for an imaging apparatus having a media feed path includes a pair of media support members, each have a first wall defining a media contact surface and a support portion defining a media support surface. The pair of media support members are pivotally mounted to the imaging apparatus for symmetrical operation with respect to a centerline of the media feed path. The pair of media support members define a media bin for receiving printed media. The print media handling system further includes a drive system for operating the pair of media support members between a first position wherein the media support surface of the pair of support members carries a printed media sheet and a second position wherein the printed media sheet is released to fall into the media bin.

Abstract: A sheet processing apparatus has a sheet stacking tray supported for upward and downward movement, a lifting/lowering unit for lifting and lowering the sheet stacking tray, a first sensor for sensing the uppermost surface position of a batch of sheets on the stacking tray and lowering the stacking tray a prescribed amount through the lifting/lowering unit, and a second sensor for sensing that the batch of sheets on the stacking tray is partly drawn out and lifting the stacking tray through the lifting/lowering means to thereby return the stacking tray to a position proper to discharge sheets.

Abstract: A sheet post-processing apparatus comprises a conveyer for conveying the sheets discharged from the image forming system; a conveying device for conveying the sheets discharged from the image forming system; a pair of upper trays for accommodating the sheets conveyed by the conveying devices, and being horizontally moved in order to align the sheets accommodated therein and fall down the aligned sheets; a pair of upper tray driving devices for providing a driving force to the upper trays; a transmission unit for transmitting the driving force of the upper tray driving device to the upper trays; a lower tray for loading the sheets fallen from the upper trays; and a lower tray driving device for moving the lower tray in upper and lower directions in order to retain distance between the upper trays and the lower tray within a predetermined range. Thus, the sheet post-processing apparatus can accommodate variant size sheets by mechanism consisting of simple and cheap elements.