Sheet Discharging Device and Sheet Post-Processing Apparatus Therewith, and Image Forming System

This application is based on and claims the benefit of priority from Japanese Patent Application No. 2024-054357 filed on Mar. 28, 2024, the contents of which are hereby incorporated by reference.

The present disclosure relates to a sheet discharging device and a sheet post-processing apparatus incorporating the same, and also relates to an image forming system.

Conventional sheet post-processing apparatuses incorporate a sheet discharging device. The sheet discharging device includes a pair of discharging rollers, a stacking tray, a protruding member, and a moving mechanism. The pair of discharging rollers discharges a sheet through a discharge port. The stacking tray is disposed downstream of the pair of discharging rollers with respect to the sheet discharging direction and is stacked with sheets discharged by the pair of discharging rollers.

The protruding member is supported so as to be reciprocatable between a protrusion position and a retraction position. In the protrusion position, the protruding member protrudes from the discharge port to above the stacking tray and brings, into contact with its top surface, the leading edge of the sheet discharged by the pair of discharging rollers to guide it in the discharging direction. In the retraction position, the protruding member is retracted from above the stacking tray. The moving mechanism moves the protruding member between the protrusion position and the retraction position.

Inconveniently, in conventional sheet discharging devices provided with a sensing portion for checking whether the protruding member is in the retraction position, there is a risk of the sensing portion breaking by touching a component around it when the protruding member moves.

In view of the above inconvenience, an object of the present disclosure is to provide a sheet discharging device less prone to breakage.

To attain the above object, according to a first aspect of the present disclosure, a sheet discharging device includes a pair of discharging rollers, a stacking tray, a protruding member, a supporting holder, and a moving mechanism. The pair of discharging rollers discharges a sheet through a discharge port. The stacking tray is disposed downstream of the pair of discharging rollers with respect to the discharging direction of the sheet and has stacked on it the sheet discharged by the pair of discharging rollers. The protruding member is supported so as to be reciprocatable between a protrusion position and a retraction position. The protrusion position is where the protruding member protrudes from the discharge port to above the stacking tray and brings, into contact with its top surface, the leading edge of the sheet discharged by the pair of discharging rollers to guide it in the discharging direction. The retraction position is where the protruding member is retracted from above the stacking tray. The moving mechanism has a supporting holder movably holding the protruding member and makes the held protruding member move between the protrusion position and the retraction position. The sheet discharging device further includes a sensing portion sensing whether the protruding member is in the retraction position, and the sensing portion is disposed in the supporting holder.

This and other objects of the present disclosure, and the specific benefits obtained according to the present disclosure, will become apparent from the description of embodiments which follows.

Now, a description will be given of a sheet post-processing apparatusand an image forming system S configured with the sheet post-processing apparatusaccording to an embodiment of the present disclosure with reference to the accompanying drawings.

1. Configuration of Image Forming System:is a schematic diagram of an image forming system S including an image forming apparatusand a sheet post-processing apparatusaccording to an embodiment of the present disclosure. The image forming system S includes the image forming apparatusand the sheet post-processing apparatus.

The image forming apparatusis what is called a multifunction peripheral capable of monochrome printing equipped with the functions of, for example, printing (copying), scanning (image reading), facsimile transmission, and the like. The image forming apparatusincludes a document conveying portionand an image reading portion. The document conveying portionis placed on the top face of a body portion. The image reading portionis disposed below Zthe document conveying portion, inside the body portion. The image of a document placed on the document conveying portionor of a document placed on a contact glass, not shown, on the top face of the image reading portionis read by the image reading portion.

The image forming apparatusfurther includes a sheet feeding portion, a sheet conveying portion, an exposure portion, an image forming portion, a transferring portion, a fixing portion, a sheet discharging portion, a relay portion, and a body control portion.

The sheet feeding portionstores a plurality of sheets P and feeds out, while separating, the sheets P one by one during printing. The sheet conveying portionconveys a sheet P fed from the sheet feeding portionto the transferring portionand then the fixing portion, and also sorts the sheet P after fixing to the sheet discharging portionor to the relay portion. The exposure portionshines laser light controlled based on image data toward the image forming portion.

The image forming portionincludes a photosensitive drumas an image carrying member and a development device. In the image forming portion, the laser light shone from the exposure portionforms, on the surface of the photosensitive drum, an electrostatic latent image based on a document image. The development devicefeeds toner to the electrostatic latent image to develop it into a toner image. The transferring portiontransfers, to the sheet P, the toner image that the image forming portionhas formed on the surface of the photosensitive drum. The fixing portionheats and presses the sheet P having the toner image transferred to it so as to fix the toner image to the sheet P.

The sheet P after fixing is conveyed to the sheet discharging portionor to the relay portion. The sheet discharging portionis disposed below Zthe image reading portion. The sheet discharging portionhas an opening in its front face and permits the sheet after printing (printed matter) to be retrieved at the front. The relay portionis disposed below the sheet discharging portion. The relay portionhas its downstream end in the sheet conveying direction coupled to the sheet post-processing apparatus. The sheet after printing (printed matter) conveyed to the relay portionpasses through the relay portionto be conveyed to the sheet post-processing apparatus.

The body control portionincludes a CPU, an image processing portion, and a memory, none of which is shown, along with other electronic circuits and components, none of which is shown. The CPU controls the operation of different components provided in the image forming apparatusbased on programs and data for control stored in the memory to perform processes to carry out the functions of the image forming apparatus. The sheet feeding portion, the sheet conveying portion, the exposure portion, the image forming portion, the transferring portion, and the fixing portionindividually receive commands from the body control portionand cooperate to perform printing on the sheet P. The memory is configured as a combination of a nonvolatile memory device such as a program ROM (read only memory) and a data ROM, and a volatile memory device such as a RAM (random access memory), none of which is shown.

The sheet post-processing apparatusis removably coupled to the image forming apparatusfrom a side face of it. The sheet post-processing apparatusincludes a post-processing housing, a sheet conveying passagedisposed in the post-processing housing, a processing tray, a punching portion, a stapling portion, a pair of conveying rollers, a pair of intermediate rollers, a first sheet sensing portion S, a pair of discharging rollers, a second sheet sensing portion S, a sheet discharging device, and a post-processing control portion.

In the embodiment, the punching portionand the stapling portionconstitute a post-processing mechanism. In other words, the sheet post-processing apparatusincludes a post-processing mechanism and the post-processing mechanism performs predetermined post-processing on the sheet P and conveys the post-processed sheet P to the sheet discharging device.

The post-processing housinghas a sheet introduction portprovided in a side face of it opposite the image forming apparatus. The sheet P having passed through the relay portionpasses through the sheet introduction portto be introduced into the sheet post-processing apparatus.

The sheet conveying passageextends from the sheet introduction portto above Zthe processing trayin the direction away from the image forming apparatus(leftward in). On the top face of the processing tray, the sheet P can be temporarily stacked. The sheet conveying passagestacks the sheet P introduced through the sheet introduction porton the top face of the processing tray.

The processing trayis inclined so as to have a downward slope from its downstream end toward its upstream end in the sheet conveying direction (X-Xdirection).

The punching portionis disposed between the sheet introduction portand the downstream end of the sheet conveying passagewith respect to the sheet conveying direction (X-Xdirection). The punching portionpunches the sheet P conveyed through the sheet conveying passage. Punching is processing to form punched holes (binding holes). Here, punched holes are formed along one side edge of the sheet along its width direction (Y-Ydirection) orthogonal to the sheet conveying direction (X-Xdirection).

The stapling portionis disposed below Zthe sheet conveying passage, upstream Xof the processing trayin the sheet conveying direction (X-Xdirection). The stapling portionstaples (binds) a bundle of sheets P stacked on the processing tray. Stapling is processing to bind the bundle of sheets P with a staple. Here, what is called edge binding is carried out, in which a corner part or an edge part of the bundle of sheets is bound with a staple.

The post-processing mechanism includes the pair of conveying rollers, the pair of intermediate rollers, and the first sheet sensing portion Sarrayed in this order from upstream Xin the sheet conveying direction, and the pair of conveying rollersand the pair of intermediate rollersconvey the post-processed sheet P to the sheet discharging device.

The pair of conveying rollersis disposed downstream of the punching portion, adjacent to it, with respect to the sheet conveying direction (X-Xdirection). The pair of conveying rollersconveys the punched or unpunched sheet downstream Xin the sheet conveying direction.

The pair of intermediate rollersis disposed in a downstream end part of the sheet conveying passagewith respect to the sheet conveying direction (X-Xdirection). The pair of intermediate rollersis located above Zan upstream end part of the processing tray. The pair of intermediate rollersdischarges the sheet P conveyed through the sheet introduction portinto the sheet conveying passageonto the processing tray.

The first sheet sensing portion Sis disposed closely downstream of the pair of intermediate rollerswith respect to the sheet discharging direction (see). The first sheet sensing portion Sis a sensor that optically senses the sheet P; it senses the entry of the leading edge of the sheet P conveyed by the pair of conveying rollersinto the pair of intermediate rollers. The first sheet sensing portion Salso senses the passage of the sheet P conveyed by the pair of intermediate rollersthrough the pair of intermediate rollers.

2. Configuration of Sheet Discharging Device:is a side sectional view schematically showing the internal structure of the sheet discharging device. The sheet discharging deviceincludes a pair of discharging rollers, a stacking tray, a sheet pressing member, a paddle member, and a post-processing control portion. The sheet discharging devicefurther includes, in addition to the components just mentioned, a protruding member, a moving mechanism, and a sensing portion, of which the configuration will be described in detail later.

The pair of discharging rollersdischarges the sheet through a discharge port. The pair of discharging rollersis disposed downstream of the pair of intermediate rollerswith respect to the sheet discharging direction. The pair of discharging rollersoverlaps with a downstream end part of the processing traywith respect to the sheet discharging direction.

The pair of discharging rollersincludes a driving roller(discharging roller) and a driven rollerin pressed contact with the driving rollerunder a predetermined nip pressure. The driving rollerand the driven rollertogether form a nip portionN that nips and conveys the sheet P. The nip portionN is released by a nip release mechanism (not shown) when the stapling portioncarries out stapling. The sheet P is stacked on the processing traywith the nip portionN released. The stapled bundle of sheets is discharged to the stacking trayby the pair of discharging rollerswith the nip portionN restored.

The driving rolleris supported on a driving roller shaftso as to rotate together with the driving roller shaftTo the driving roller shafta drive source such as a motor is connected (not shown) and its rotation is controlled by the post-processing control portion. As the driving roller shaftrotates, the two driving rollersrotate concurrently together with the driving roller shaft

The second sheet sensing portion Sis disposed closely downstream of the pair of discharging rollers. The second sheet sensing portion Sincludes an actuator and a photosensor (neither is shown) and can sense whether the sheet P is being discharged and whether the trailing end of the sheet P has passed through the pair of discharging rollers.

The stacking trayis disposed downstream of the pair of discharging rollerswith respect to the discharging direction of the sheet P and has stacked on it the sheet P discharged by the pair of discharging rollers. The stacking trayis supported such that it can ascend and descend. The stacking trayhas a sheet stacking faceformed on its top face. A sheet propping wallconstitutes the side face of the post-processing housingopposite from the image formation apparatus. The sheet stacking faceis inclined upward Zas it extends away from the sheet propping wallAn upstream end part of the sheet stacking facewith respect to the sheet discharging direction is located below Zthe pair of discharging rollers.

The stacking trayis a final discharge location for the sheet in the sheet post-processing apparatus. The bundle of sheets stapled on the processing trayis discharged toward the stacking trayby the pair of discharging rollersand is stacked on the sheet stacking faceIf no stapling is carried out by the stapling portion, the sheet P is conveyed to the stacking traywithout being stacked on the processing tray.

The post-processing control portionincludes a CPU, which is not shown, and other electronic circuits and components, none of which is shown. The post-processing control portionis connected to the body control portionsuch that it can communicate with each other. The post-processing control portionreceives commands from the body control portionand controls, with the CPU and based on programs and data for control stored in the memory, the operation of different components (the punching portion, the stapling portion, the pair of conveying rollers, the pair of intermediate rollers, the pair of discharging rollers, the processing tray, the sheet discharging device, the moving mechanism, and the like) in the sheet post-processing apparatusto perform processes to carry out the functions of the sheet post-processing apparatus.

The sheet pressing memberis disposed upstream of the stacking trayin the sheet discharging direction. The sheet pressing memberis disposed below Zthe driving roller shaftTwo sheet pressing membersare disposed along the sheet width direction (Y-Ydirection) of the stacking trayat a predetermined interval in the sheet width direction (Y-Ydirection).

The sheet pressing memberis supported in a lower end part of it so as to be swingable about, as a fulcrum, a swing shaftextending along the sheet width direction (Y-Ydirection). The sheet pressing memberswings, with one end part of it at its top as a free end, about the swing shaftin the sheet discharging direction. The sheet pressing memberswings between a position where it presses, from above Z, an upstream part of the sheet stacked on the stacking trayin the discharging direction and a position where it releases the pressing of the sheets. The swinging of the sheet pressing memberis controlled by the post-processing control portion.

The sheet pressing memberpresses the trailing end of the sheet P stacked on the sheet stacking facefrom above Z. Thus, even if the sheet to be discharged is curled, it is possible to straighten the sheet by pressing its trailing end.

A plurality of (here, four) paddle membersare provided coaxially with the driving roller shaftThe paddle membersrotate independently of the driving roller shaftThe four paddle membersare connected to a drive source such as a motor (not shown) and their rotation is controlled by the post-processing control portion.

Before the start of the discharge of the sheet P, the sheet pressing membersstay still in a position where they do not protrude toward the stacking trayso as not to hinder the discharge of the sheet P. In addition, before the start of the discharge of the sheet P, the paddle membersstand by in a position where they do not protrude toward either the processing trayor the stacking trayso as not to hinder the discharge of the sheet P.

The post-processing control portionstarts to rotate the paddle membersafter the trailing end of the sheet P (an upstream end part of it in the sheet discharging direction) has passed through the nip portionN, before the sheet P is stacked on the sheet stacking face. Then, the paddle membersmake contact with the trailing end of the sheet P discharged from the pair of discharging rollersand pushes down from above Z, as if tapping, a part of the sheet P near its trailing end toward the sheet stacking face

From this state, as the paddle membersfurther rotate, the paddle members, while pulling the sheet P upstream in the discharging direction of the sheet P along the stacking tray, press a part of the sheet P near its trailing end against the sheet propping wallof the stacking tray.

After the paddle membersstart to rotate, before they pass across the upstream end of the stacking trayin the sheet discharging direction, the sheet pressing membersstart to be swung. Then, the sheet pressing membermoves to a pressing position at which it presses, from above Z, an upstream part of the sheet stacked on the stacking trayin the discharging direction.

When the sheet post-processing apparatusends the stacking of the sheet, the upstream end of the sheet P in the discharging direction makes contact with the sheet propping wallprovided upstream of the stacking trayin the sheet discharging direction. Thus, the sheet P is aligned at a predetermined position on the stacking tray.

3. Configuration of Protruding Member and Moving Mechanism:is a perspective view of the structure around the protruding memberin the sheet discharging device.is an enlarged perspective view of the structure around the protruding member.is a side view of a supporting holderas seen from an axial direction. Note that, in, the sensing portionis hatched for clarity.is an enlarged perspective view of the structure around a tip part of the protruding member.

The protruding memberis a member in the shape of a rod extending along the sheet discharging direction in the form of an arc. The protruding memberis disposed below Zthe sheet discharge port(see). Specifically, the protruding memberis disposed below Zthe discharging passage of the sheet discharged from the pair of discharging rollersalong the processing tray. A plurality of (in the embodiment, two) protruding membersare provided at a predetermined interval across a middle part of the stacking traywith respect to the sheet width direction (Y-Ydirection). The protruding memberand the paddle memberare disposed side by side with respect to the sheet width direction (Y-Ydirection).

The supporting holderis fixed to the post-processing housingand is included in the moving mechanism, which will be described later. The supporting holderis provided one at each of positions overlapping with the protruding memberswith respect to the sheet width direction (Y-Ydirection) (see).

The supporting holderhas side wallsanda guide rail, a cover rib, and a positioning protrusion(see).

The side wallsandare plate-form parts formed at opposite ends of the supporting holderwith respect to the axial direction (Y-Ydirection). The side wallsandface each other along the axial direction (Y-Ydirection). The side wallsandhave a collar supporting holepenetrating them along the axial direction (Y-Ydirection). The protruding memberis disposed between the side wallsandwith respect to the axial direction (Y-Ydirection).

The guide railhas the shape of a rib protruding from the side wallsandinward of the supporting holderwith respect to the axial direction (Y-Ydirection). The guide railextends along the arc shape of the protruding member, parallel to the movement direction of the protruding member. The cover ribis provided opposite the guide railwith respect to the direction orthogonal to both the axial direction (Y-Ydirection) and the sheet discharging direction. A gap is formed between the cover riband the guide rail.