SHEET POSTPROCESSING DEVICE AND IMAGE FORMING SYSTEM INCLUDING THE SHEET POSTPROCESSING DEVICE

The sheet postprocessing device includes a conveyance member, a processing tray, a processing part, a discharge member, a sheet discharge tray, a support member, a drive mechanism, and a controller. The sheet discharge tray is placed on a downstream side of the processing tray in a discharge direction, and the sheet discharged from the processing tray is to be stacked. The support member is movable by the drive mechanism between a projective position in which the support member is projected from a downstream-side end portion of the processing tray in the discharge direction, to above the sheet discharge tray so as to support part of the sheet carried in onto the processing tray, and a retractive position in which the support member has retracted to an upstream side of the discharge member in the discharge direction. The controller is enabled to adjust the projective position of the support member.

INCORPORATION BY REFERENCE

This application is based on and claims the benefit of priority from Japanese Patent Application No. 2023-005570 filed on Jan. 18, 2023, the contents of which are hereby incorporated by reference.

BACKGROUND

The present disclosure relates to a sheet postprocessing device by which sheets having been subjected to image formation by an image forming apparatus are further subjected to specified postprocessing, and also relates to an image forming system including the sheet postprocessing device.

Conventionally, there has been known a sheet postprocessing device by which, after sheets subjected to image formation by an image forming apparatus such as copiers or printers are stacked in plurality, those stacked sheets are further subjected to such processes as a stapling process of bundling and stapling the stacked sheets, a punch-hole forming process of boring punch holes in those sheets with a punch-hole forming device, and a folding process of forming fold lines in the sheets.

Such a sheet postprocessing device shown above is equipped with a processing tray on which sheets having images formed thereon are to be stacked to a specified sheet count. Then, a plurality of sheets stacked on the processing tray are subjected to a stapling process, a shift discharge process (sorting process), and the like. Further, in order to smoothly carry out the stapling process, the shift discharge process and the like, it is also practiced that with use of an alignment paddle or other alignment member, sheets on the processing tray are pushed against reference plates so as to be aligned along their carry-in direction.

In this case, when the processing tray is longer than a sheet as measured in a sheet conveyance direction, it is implementable to achieve a stable stacking of sheets. However, this case would lead to increased sizes of the sheet postprocessing device as well as to increased manufacturing costs. For this reason, the conveyance-direction size of the processing tray is designed as small as possible, such that sheets are stacked as partly projected outward of the device (toward a discharge tray). In this case, attempting to achieve sheet alignment in its carry-in direction with an aligning member would encounter a difficulty that the portion of sheets projected outward of the device is hung down to make a resistance to carry in the sheets, so that the sheets are less likely to be conveyed up to the reference plates.

SUMMARY

A sheet postprocessing device according to one aspect of the present disclosure includes a conveyance member, a processing tray, a processing part, a discharge member, a sheet discharge tray, a support member, a drive mechanism, and a controller. The conveyance member conveys a sheet. On the processing tray, a plurality of sheets conveyed along a specified carry-in direction by the conveyance member are stacked. The processing part performs specified postprocessing on the sheets stacked on the processing tray. The discharge member conveys the sheets on the processing tray in a discharge direction. The sheet discharge tray is placed on a downstream side of the processing tray in the discharge direction, and the sheets discharged from the processing tray are to be stacked thereon. The support member is movable between a projective position in which the support member is projected from a downstream-side end portion of the processing tray in the discharge direction, to above the sheet discharge tray so as to support part of the sheet carry-in onto the processing tray, and a retractive position in which the support member has retracted from the projective position to an upstream side of the discharge member in the discharge direction. The drive mechanism drives the support member. The controller controls the drive mechanism. The controller is enabled to adjust the projective position of the support member.

DETAILED DESCRIPTION

1. Configuration of Image Forming System

Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings.FIG.1is a schematic view showing a configuration of an image forming system which consists of a sheet postprocessing device1according to one embodiment of the disclosure, and an image forming apparatus200to which the sheet postprocessing device is coupled.

As shown inFIG.1, the image forming apparatus200prints out an image on a sheet (paper) on a basis of image data inputted from external via an unshown network communication part or image data read by an image reading part201placed on top of the image forming apparatus200. In this embodiment, the image forming apparatus200is an inkjet recording apparatus which includes recording heads (not shown) provided on an each-color basis and equipped with a multiplicity of nozzle holes through which ink is jetted out onto a sheet.

An operation panel202is placed forward of the image reading part201. The operation panel202is an operation part for accepting various types of setting inputs. For example, a user is enabled to enter sheet-size information by operating the operation panel202. Also by operating the operation panel202, the user is allowed to enter a number of sheets to be printed and to instruct for a start of a print job. A main body controller203administers overall operations of the image forming apparatus200and controls individual parts of the image forming apparatus200.

The sheet postprocessing device1is removably coupled to a side face of the image forming apparatus200. The sheet postprocessing device1performs such postprocessing as a punch-hole forming process and a stapling process on a sheet having been subjected to image formation (printing) by the image forming apparatus200. It is noted that the sheet postprocessing device1is not limited to one which performs postprocessing on a sheet automatically conveyed from the image forming apparatus200, and may be one which allows a user to set a sheet on an unshown tray, the sheet then being conveyed up to a postprocessing-enabled position by the device itself and subjected to postprocessing.

2. Configuration of Sheet Postprocessing Device

FIG.2is a side sectional view schematically showing a configuration of the sheet postprocessing device1in this embodiment. The sheet postprocessing device1, as shown inFIG.2, includes a sheet inlet2, a first sheet conveyance path3, a first sheet discharge part4, a second sheet conveyance path5, a second sheet discharge part6, a third sheet conveyance path7, a third sheet discharge part8, a postprocessing part9, and a postprocessing controller (controller)10.

The sheet inlet2is an opening provided in a side face of the sheet postprocessing device1facing the image forming apparatus200. A sheet conveyed from the image forming apparatus200toward the sheet postprocessing device1is conveyed through the sheet inlet2so as to be carried into the sheet postprocessing device1.

The first sheet conveyance path3extends from the sheet inlet2to the first sheet discharge part4in such a generally horizontal direction (leftward direction inFIG.2) as to become farther from the image forming apparatus200. It is noted that a direction from the sheet inlet2toward the first sheet discharge part4is referred to as a sheet conveyance direction of the first sheet conveyance path3. The sheet inlet2is located at an upstream end of the first sheet conveyance path3in the sheet conveyance direction. The first sheet conveyance path3, having thereon a plurality of conveyance roller pairs3r, conveys a sheet, which has been delivered through the sheet inlet2into the sheet postprocessing device1, toward a downstream side in the sheet conveyance direction.

The first sheet discharge part4is provided on a side face of the sheet postprocessing device1opposite to its side face facing the image forming apparatus200. The first sheet discharge part4is placed at a downstream end of the first sheet conveyance path3in the sheet conveyance direction. The first sheet discharge part4includes a first discharge port41, a first discharge roller pair42, and a first discharge tray43.

The first discharge port41is located at a downstream end of the first sheet conveyance path3in the sheet conveyance direction. The first discharge roller pair42is placed at the first discharge port41. The first discharge tray43is located downstream of the first discharge port41in the sheet conveyance direction. A sheet conveyed along the first sheet conveyance path3and having reached the first discharge port41is passed through the first discharge port41and discharged onto the first discharge tray43by the first discharge roller pair42. The first discharge tray43is one of terminal discharge places for sheets subjected to postprocessing by the sheet postprocessing device1.

The second sheet conveyance path5, branching from a first branch portion (branch portion)31on the first sheet conveyance path3, extends up to the second sheet discharge part6laterally and upwardly in such a direction as to become farther from the image forming apparatus200(leftward direction inFIG.2). The first branch portion31is placed downstream of a punching portion91in the first sheet conveyance path3in the sheet conveyance direction. It is noted that a direction directed from the first branch portion31toward the second sheet discharge part6is referred to as a sheet conveyance direction of the second sheet conveyance path5. The first branch portion31is located at an upstream end of the second sheet conveyance path5in the sheet conveyance direction. The second sheet conveyance path5, having a plurality of conveyance roller pairs5r, leads a sheet, which is under conveyance on the first sheet conveyance path3, such that the sheet branches at the first branch portion31so as to be conveyed toward the second sheet discharge part6.

The first branch portion31includes a first switching guide311. The first switching guide311pivotally turns between a position in which a sheet conveyed on the first sheet conveyance path3from the sheet inlet2side is guided along the first sheet conveyance path3to the first discharge port41, and another position in which the sheet is made to branch from the first sheet conveyance path3so as to be guided to the second sheet conveyance path5. The first switching guide311further pivotally turns to yet another position in which a sheet subjected to a folding process and having passed through a later-described second folding conveyance path106is guided to the second sheet conveyance path5. The first switching guide311is connected to a drive mechanism (not shown) and controlled in its operation by the postprocessing controller10.

The second sheet discharge part6is provided upward of the first sheet discharge part4and on the side face of the sheet postprocessing device1opposite to its side face facing the image forming apparatus200. The second sheet discharge part6is placed at a downstream end of the second sheet conveyance path5in the sheet conveyance direction. The second sheet discharge part6includes a second discharge port61, a second discharge roller pair62, and a second discharge tray63.

The second discharge port61is located at a downstream end of the second sheet conveyance path5in the sheet conveyance direction. The second discharge roller pair62is placed at the second discharge port61. The second discharge tray63is located downstream of the second discharge port61in the sheet conveyance direction. A sheet conveyed along the second sheet conveyance path5and having reached the second discharge port61is passed through the second discharge port61and discharged onto the second discharge tray63by the second discharge roller pair62. The second discharge tray63is one of the terminal discharge places for sheets subjected to postprocessing by the sheet postprocessing device1. In addition, such sheets as those destined for no postprocessing and those of smaller sizes are also discharged onto the second discharge tray63.

The third sheet conveyance path7, branching from a second branch portion32on the first sheet conveyance path3, extends downward to the third sheet discharge part8. It is noted that a direction directed from the second branch portion32toward the third sheet discharge part8is referred to as a sheet conveyance direction of the third sheet conveyance path7. The second branch portion32is located on a downstream side of the first branch portion31in the sheet conveyance direction of the first sheet conveyance path3, and moreover located at an upstream end of the third sheet conveyance path7in the sheet conveyance direction. The third sheet conveyance path7, having a plurality of conveyance roller pairs7r, leads a sheet, which is under conveyance on the first sheet conveyance path3, such that the sheet is made to branch at the second branch portion32and conveyed toward the third sheet discharge part8.

The second branch portion32includes a second switching guide321. The second switching guide321pivotally turns between a position in which a sheet conveyed on the first sheet conveyance path3from the sheet inlet2side is guided along the first sheet conveyance path3to the first discharge port41, and another position in which a sheet, which is switched back after conveyance on the first sheet conveyance path3from the sheet inlet2side and passage through the second branch portion32, is led to the third sheet conveyance path7. The second switching guide321is connected to a drive mechanism (not shown) and controlled in its operation by the postprocessing controller10.

The third sheet discharge part8is provided downward of the first sheet discharge part4(near a lower end portion of the sheet postprocessing device1) and on the side face of the sheet postprocessing device1opposite to its side face facing the image forming apparatus200. The third sheet discharge part8includes a third discharge port81, a third discharge roller pair82, and a third discharge tray83.

The third discharge port81is located at a downstream end of the third sheet conveyance path7in the sheet conveyance direction. The third discharge roller pair82is placed at the third discharge port81. The third discharge tray83is located downstream of the third discharge port81in the sheet conveyance direction. A sheet conveyed on the third sheet conveyance path7and having reached the third discharge port81is passed through the third discharge port81and discharged onto the third discharge tray83by the third discharge roller pair82. The third discharge tray83is one of the terminal discharge places for sheets subjected to postprocessing by the sheet postprocessing device1.

The postprocessing part9performs specified postprocessing on a sheet subjected to image formation by the image forming apparatus200and carried into the sheet postprocessing device1. The postprocessing part9includes the punching portion91, a sheet stapling unit92, a sheet folding unit100, and a bookbinding portion94.

The punching portion91is placed in downstream-side close vicinity of the sheet inlet2in the first sheet conveyance path3. The punching portion91performs a punching process on a sheet conveyed on the first sheet conveyance path3, making a punch hole or holes formed thereon.

The sheet stapling unit92is placed in upstream-side close vicinity of the first sheet discharge part4as viewed in the sheet conveyance direction of the first sheet conveyance path3. The sheet stapling unit92performs a stapling process on a sheet bundle formed by stacking a plurality of sheets, so that the sheet bundle is stapled. A detailed configuration of the sheet stapling unit92will be described later.

The sheet folding unit100is placed downstream of the punching portion91and upstream of the sheet stapling unit92, as viewed in the sheet conveyance direction of the first sheet conveyance path3. The sheet folding unit100performs a folding process on one sheet to form a fold or folds thereon. The sheet folding unit100is enabled to perform, for one sheet, such folding processes as two-folding, Z-folding, outward three-folding, and inward three-folding.

The bookbinding portion94is placed in upstream-side close vicinity of the third sheet discharge part8as viewed in the sheet conveyance direction of the third sheet conveyance path7. The bookbinding portion94includes a middle-folding part941, and a saddle-stitching part942. The bookbinding portion94performs, on a sheet bundle formed by stacking a plurality of sheets, a middle-folding process and a saddle-stitching process for folding and stitching a generally central portion of the sheet bundle in the sheet conveyance direction to make up a booklet.

The postprocessing controller (controller)10includes a CPU, a storage part, and other electronic circuits and electronic components (none shown). The postprocessing controller10is communicably connected to the main body controller203of the image forming apparatus200(seeFIG.1). The postprocessing controller10, receiving a command from the main body controller203, controls operations of individual components provided in the sheet postprocessing device1on a basis of control programs and data stored in the storage part with use of the CPU, thereby fulfilling processes related to functions of the sheet postprocessing device1. The first sheet conveyance path3, the first sheet discharge part4, the second sheet conveyance path5, the second sheet discharge part6, the third sheet conveyance path7, the third sheet discharge part8, and the postprocessing part9individually receiving commands from the postprocessing controller10, perform postprocessing on a sheet in linkage with one another. In addition, instead, the functions of the postprocessing controller10may also be fulfilled by the main body controller203of the image forming apparatus200in addition to its inherent functions.

3. Configuration of Sheet Stapling Unit

Next, a configuration of the sheet stapling unit92is described.FIG.3is a perspective view of the sheet stapling unit92which is mounted on the sheet postprocessing device1.FIG.4is a side view of the sheet stapling unit92.

As shown inFIG.3, the sheet stapling unit92includes a processing tray521, a stapling part71, and reference plates73.

The processing tray521is a rectangular-shaped tray extending in a sheet widthwise direction (arrow A-A′ direction) as well as in a carry-in direction. A plurality of sheets S (sheet bundle) to be subjected to the stapling process are stacked on the processing tray521. In this case, each sheet S is delivered onto the processing tray521along an alignment direction (a direction opposite to the carry-in direction) directed toward lower right ofFIG.4(arrow B direction). The sheet bundle subjected to the stapling process is finally sent out by the first discharge roller pair42(seeFIG.2) in a direction opposite to the aforementioned alignment direction (a direction toward upper left inFIG.4) so as to be discharged onto the first discharge tray43(seeFIG.2). A discharge lower roller421which is one component of the first discharge roller pair42is supported on a delivery-direction downstream side (lower left side inFIG.3) of the processing tray521.

The processing tray521includes a tray central portion522and width-restricting members523. The tray central portion522is placed at a central portion in the sheet-widthwise direction in a top face portion of the processing tray521. The tray central portion522is a thin-plate like member which is fixed on the processing tray521with a slight height.

The width-restricting members523are placed in one pair so as to make the tray central portion522interposed therebetween in the sheet widthwise direction. The width-restricting members523restrict a sheet-widthwise position of a sheet S to be carried onto the processing tray521. Each width-restricting member523, which is a thin-plate like member as the tray central portion522is, has a side wall which is provided at a sheet-widthwise end portion so as to be erected upward. The processing tray521has a guide recess524formed therein so as to extend along the sheet widthwise direction. The width-restricting member523is enabled to reciprocate in the sheet widthwise direction along the guide recess524via a drive mechanism (not shown) such as a rack-and-pinion gear. In this embodiment, each time a sheet is delivered onto the processing tray521, the width-restricting members523are reciprocatively moved by the drive mechanism. As a result, sheets stacked on the processing tray521are aligned in the sheet widthwise direction.

The stapling part71is placed in opposition to a fore-end-side (right side inFIG.4) end edge of the sheet in the alignment direction. The stapling part71, being movable along the end edge of the sheet in the sheet widthwise direction (arrow A-A′ direction) perpendicular to the carry-in direction by driving force of a stapling-part driving motor M1, performs the stapling process on a sheet bundle.

As shown inFIG.4, the stapling part71includes a stapling main portion711, and a stapling movable portion712. The stapling main portion711, being a main portion of the stapling part71, internally contains a plurality of stapling needles (not shown). The stapling movable portion712, being made up/down movable, inserts the stapling needles into a sheet. A recessed portion713into which the end edge of a sheet is to come is formed between the stapling main portion711and the stapling movable portion712.

The reference plates73are fixed at three places separated from one another with sheet-widthwise intervals so as to be opposed to a downstream-side (upper right side inFIG.3, lower right side inFIG.4) end portion of the processing tray521, in the alignment direction. Each reference plate73is generally U-shaped with its alignment-direction upstream side (upper left side inFIG.4) opened, in a cross section perpendicular to the sheet widthwise direction. The reference plate73makes contact with the end edge of the sheet carried onto the processing tray521so as to align the sheet in the carry-in direction.

4. Configuration of Around Processing Tray in Sheet Stapling Unit

FIG.5is a side sectional view showing a structure of around the processing tray521and a support member58. As shown inFIG.5, a carry-in roller pair54is placed upward of the processing tray521. The carry-in roller pair54is composed of a carry-in upper roller54aand a carry-in lower roller54b.

A sheet detection sensor93is placed in vicinity of the carry-in roller pair54. The sheet detection sensor93detects a timing at which the sheet S has passed through the carry-in roller pair54. As the sheet detection sensor93, a PI (photointerrupter) sensor including a detector part composed of a light-emitting part and a light-receiving part is used as an example.

A tapping member53and an alignment member55are provided on a downstream side (left side inFIG.5) of the carry-in roller pair54as viewed in the delivery direction of the sheet S. The tapping member53is swingably supported along the carry-in direction of the sheet S. The tapping member53swings downward at a timing when a rear end of the sheet S has passed through the carry-in roller pair54, so that the sheet S is tapped downward so as to be aligned along the processing tray521.

The alignment member55is placed at a plurality of places (four places in this embodiment) along the sheet widthwise direction (a direction perpendicular to the drawing sheet ofFIG.5). The alignment member55makes the sheet S, which is about to be delivered onto the processing tray521, moved (switched back) in such an alignment direction that the sheet S gets nearer to the reference plates73, thus giving aid for sheet alignment. The alignment member55includes a paddle holder56and an alignment paddle57.

The paddle holder56is supported upward of the processing tray521so as to be swingable along the carry-in direction of the sheet S. Rotation driving force is inputted to a swinging shaft56aof the paddle holder56by a paddle driving motor (not shown). Inputted to the alignment paddle57by a drive source (not shown) such as a motor is rotation driving force in such a direction (counterclockwise direction inFIG.5) as to send out the sheet S in the alignment direction. As the alignment paddle57is rotated in contact with a top face of the sheet S that is delivered onto the processing tray521, the sheet S is moved in an alignment direction so that end edges of the sheet S are thrust against the reference plates73, thus the sheet S being aligned.

Swings of the paddle holder56are controlled based on a detection timing of the sheet detection sensor93. More specifically, at a timing when the sheet detection sensor93detects that the fore end of the sheet S has passed through the carry-in roller pair54, the paddle holder56is swung upward. As a result, the alignment paddle57is separated apart from the top face of the processing tray521(or of the sheets stacked on the processing tray521).

FIG.5shows a state immediately before a new sheet S is delivered onto the processing tray521, in which state the paddle holder56swings upward (in a clockwise direction) and the alignment paddle57is placed at a position (reference position) separate from the processing tray521. Also, the discharge lower roller421and a discharge upper roller422, both of which compose the first discharge roller pair42, are released from their nip. As a result of this, the sheet S delivered from the carry-in roller pair54onto the processing tray521once passes through the first discharge roller pair42so as to be projected above the first discharge tray43.

Then, at a timing when the end edge of the new sheet S delivered onto the processing tray521has passed under the alignment paddle57, the paddle holder56is swung in the reverse direction (counterclockwise direction). As a result of this, the alignment paddle57is placed at such a position (acting position) as to make contact with the top face of the sheet S. Repeating the above-described operation each time a sheet S is delivered makes it possible to securely put the alignment paddle57into contact with the top face of the sheet while avoiding interference between the end edge of the sheet S delivered onto the processing tray521and the alignment paddle57.

The support member58is placed downward of the processing tray521. The support member58, which is a bar-shaped member having a specified width in the sheet widthwise direction and extending in an arc shape in a discharge direction, is placed downward of the first discharge port41. More specifically, the support member58is placed downward of the processing tray521and moreover downward of a discharge path of the sheet S discharged from the first discharge roller pair42along the processing tray521. In this embodiment, the support member58is placed at two places in the sheet widthwise direction with a specified interval from the sheet-widthwise central portion of the processing tray521.

Each support member58is movable between a projective position (solid-line position inFIG.5) in which the support member58is projected to a discharge-direction downstream side (left side inFIG.5) of the first discharge roller pair42and a retractive position (broken-line position inFIG.5) in which the support member58has retracted to a discharge-direction upstream side (right side inFIG.5) of the first discharge roller pair42. The support member58is placed in the projective position upon carry-in (switch-back) of the sheet S onto the processing tray521to support part of the sheet projected to above the first discharge tray43.

FIG.6is a perspective view of a drive mechanism131for driving the support members58. The support members58are supported by the drive mechanism131shown inFIG.6and displaced along the sheet discharge direction by the drive mechanism131. The drive mechanism131includes guide rails801, drive-transmitting gears802, drive-transmitting shafts803, a driving shaft804, drive-transmitting belts805, a driving belt806, and a support-member driving motor M2.

The guide rails801, the drive-transmitting gears802, the drive-transmitting shafts803, and the drive-transmitting belts805are provided each two in number in correspondence to the two support members58. The driving shaft804, the driving belt806, and the support-member driving motor M2are provided each one in number.

The guide rails801are placed upstream of the first discharge roller pair42in the sheet discharge direction. Each guide rail801is a member which is formed into a gutter shape with its upper face opened and which extends in an arc shape in the sheet discharge direction as the support member58does. The guide rail801internally contains and supports the support member58.

The drive-transmitting gears802are placed under the guide rails801. The drive-transmitting gears802are composed of a plurality of gears engaged with one another, including a pinion gear8021positioned at a guide rail801-side terminal end and a drive-transmitting gear8022positioned at a drive-transmitting shaft803-side terminal end.

The pinion gear8021is placed immediately under the guide rail801. On a lower surface side of the support member58, a rack (not shown) composing a rack-and-pinion gear mechanism is formed. The rack has a plurality of teeth arrayed along the sheet discharge direction. The pinion gear8021is engageable with the rack of the support member58. In addition, an unshown window portion for engagement between the pinion gear8021and the rack of the support member58is formed at a place of the guide rail801adjacent to the pinion gear8021.

Each drive-transmitting shaft803is placed below the drive-transmitting gears802. The drive-transmitting shaft803extends along the sheet widthwise direction. The drive-transmitting gear8022of the drive-transmitting gears802is placed coaxial with the drive-transmitting shaft803so as to be rotatable along with the drive-transmitting shaft803.

The driving shaft804is placed downward of the drive-transmitting shafts803. The driving shaft804extends along the sheet widthwise direction.

Each drive-transmitting belt805is wound on the drive-transmitting shaft803and the driving shaft804via pulleys. In more detail, while two drive-transmitting belts805are wound on one driving shaft804, each one of the drive-transmitting belts805is wound on a mutually different drive-transmitting shaft803. The drive-transmitting belts805transmit rotational force of the driving shaft804to the drive-transmitting shafts803, respectively.

The driving belt806is wound on the driving shaft804and a rotating shaft of the support-member driving motor M2via a pulley. The driving belt806is turned around by the support-member driving motor M2. The support-member driving motor M2is given by using a stepping motor capable of controlling turning direction and turning quantity (turning angle) with high precision by pulse control.

As the support-member driving motor M2is rotated in the drive mechanism131, rotational force of the support-member driving motor M2is transmitted via the driving belt806to the driving shaft804, causing the driving shaft804to be rotated. As the driving shaft804is rotated, rotational force is transmitted via the drive-transmitting belts805to the drive-transmitting shafts803. As the drive-transmitting shafts803are rotated, rotational force is transmitted via the drive-transmitting gears802to the pinion gears8021. As a result, the two support members58are simultaneously displaced along the sheet discharge direction. Displacement of the support members58, i.e., operation of the drive mechanism131is controlled by the postprocessing controller10.

5. Adjustment Control For Projective Position of Support Member

Next, adjustment control for the projective position of the support member58is described. In this embodiment, the projective position (projective length) of each support member58is changed depending on characteristics of a sheet S which is to be carried in onto the processing tray521. In more detail, a conveyance load of a sheet S is estimated based on output information as to characteristics of the sheet S which is to be carried in onto the processing tray521, and the projective length in the projective position of the support member58is decreased continuously as the conveyance load increases more and more. The output information as to the characteristics of the sheet S includes type of the sheet S (sizes in conveyance direction and widthwise direction, grain direction, surface smoothness) as well as ink quantity to be used for image recording. Based on the output information as to the characteristics of the sheet S which is to be carried in onto the processing tray521, the postprocessing controller10transmits control signals to the support-member driving motor M2to change the projective position of the support member58.

For example, when conveyance-direction and widthwise-direction sizes of the sheet S are large ones (e.g., A3 size), there is involved large contact area between sheets S already stacked on the processing tray521plus the support member58and a sheet S that has been newly delivered onto the processing tray521. Due to this, a conveyance load involved in pulling the sheet S, which has been carried in onto the processing tray521, into the alignment direction becomes so large as to cause a fear that the sheet S cannot be pulled up to the reference plates73or that the sheet S may buckle on the processing tray521to result in occurrence of paper jam. Accordingly, the projective length of the support member58is decreased as the conveyance-direction and widthwise-direction sizes of the sheet S increase more and more.

When the sheet S is a sheet of paper, there is a tendency that fibers composing the sheet S are arrayed along a direction in which paper flows in a paper machine. This direction in which the fibers are arrayed is referred to as ‘grain direction’ of the sheet S. When the grain direction of the sheet S is parallel (short grain) to the widthwise direction, the sheet S is more likely to curl, so that the contact area between sheets S tends to become larger. Accordingly, in a case where the grain direction of the sheet S is parallel to the widthwise direction, the projective length of the support member58is made smaller.

In another case where the sheet S is low in surface smoothness (coarse surface), there is involved increased frictional resistance between sheets S already stacked on the processing tray521plus the support members58and a sheet S that has been newly delivered onto the processing tray521. Accordingly, when the sheet S is low in surface smoothness, the projective length of the support member58is made smaller.

In yet another case where the image forming apparatus200coupled to the sheet postprocessing device1is an inkjet recording apparatus, moisture quantity of the sheet S increases as ink quantity to be used for image recording increases more and more, causing frictional resistance between the sheets S to increase as well, with a result that the conveyance load is increased. Accordingly, the projective length of the support member58is made smaller as the ink quantity to be used for image recording increases more and more.

More specifically, each support member58is projected to such an extent that its fore end overlaps with the discharge lower roller421that is one component of the first discharge roller pair42. As a result, increases in the conveyance load due to the frictional resistance between sheets S can be suppressed without generating frictional resistance between a sheet S and the discharge lower roller421. In addition, in cases where, for example, the ink quantity is so small that the frictional resistance with the discharge lower roller421is negligible, it is also allowable that the sheet S is pulled onto the processing tray521with the support members58placed in their retractive positions.

An optimum projective length of the support members58in pulling the sheet S onto the processing tray521varies depending also on thickness, grammage, conveyance speed, and conveyance interval of the sheet S. For example, there is a tendency that increases in grammage of the sheet S causes the sheet S to be increased in weight so that the conveyance load is increased. However, increases in grammage also causes the sheet S to be increased in density (hardened) so that contact area between the sheets S tends to decrease. Furthermore, in some cases, impregnation quantity of ink may decrease, causing the conveyance load to be decreased.

Also, when the conveyance speed becomes higher or the conveyance interval becomes longer, ink jetted out onto the sheet S is more likely to be dried, causing the frictional resistance between the sheets S to be decreased. On the other hand, since accelerated drying of ink makes the sheet S more likely to curl, the contact area between the sheets S is increased, so that the conveyance load may be increased. That is, variations in conveyance load due to the thickness, grammage, conveyance speed, and conveyance interval of the sheet S are involved or not involved according to situations.

Consequently, there are some cases where an optimum adjustment for the projective position of the support member58cannot be achieved only by settings of the above-described size, grain direction, surface smoothness, and ink quantity of the sheet S, making it difficult to stably pull the sheet S onto the processing tray521.

Accordingly, in this embodiment, relationships between optimum projective positions (projective lengths) and output information as to sheet characteristics (size, grain direction, surface smoothness, thickness, grammage, and ink quantity of the sheet S) plus its conveyance speed and conveyance interval are empirically determined beforehand. Then, those relationships are tabulated and stored in a storage region (memory) of the main body controller203. The postprocessing controller10reads out the relationships therebetween, and makes a decision, the projective position of the support member58corresponding to the inputted output information as to the characteristics of the sheet S, and ink quantity.

FIG.7is a flowchart showing an example of adjustment control for a projective position of each support member58which is executed in the sheet postprocessing device1of the embodiment. With reference toFIGS.1to6as required, adjustment procedure for the projective position of the support member58will be described along steps ofFIG.7. In this case, it is assumed that the support member58is placed in the retractive position (broken-line positions inFIG.5) in an initial state. In the following description, output information as to the characteristics of the sheet S, as well as its conveyance speed and conveyance interval will comprehensively be also referred to simply as sheet output information.

When a stapling process command for sheets S is entered from the main body controller203of the image forming apparatus200, sheet S output information is entered along with the stapling process command (step S1). Among the sheet S output information, information as to a type of the sheet S such as size, thickness, grammage, and grain direction of the sheet S is entered from the operation panel202of the image forming apparatus200. For example, manufacturer, product name, product number and the like of the sheet S may previously be stored in the main body controller203in association with corresponding information as to the type of the sheet S. As a result of this, only a user's selection of manufacturer, product name, product number and the like of the sheet S by the operation panel202allows the main body controller203to recognize information as to the type of a sheet S for use. A conveyance speed and a conveyance interval of the sheet S are transmitted from the main body controller203of the image forming apparatus200.

For information as to ink quantity, an ink quantity to be used for image recording is calculated by the main body controller203on a basis of image data transmitted from a personal computer or other high-order device or from the image reading part201, and then transmitted from the main body controller203.

Next, on a basis of the entered sheet S output information, the postprocessing controller10determines a projective position of each support member58(step S2). As described before, the postprocessing controller10reads out a projective position of the support member58(driving pulse of the support-member driving motor M2) corresponding to the entered information as to type, ink quantity, conveyance speed and conveyance interval of the sheet S, and determines the projective position.

Next, the postprocessing controller10transmits a control signal to the support-member driving motor M2so as to make the support member58projected from the retractive position to the projective position determined by step S2(step S3). Then, carry of the sheet S, which has been carried into the sheet postprocessing device1via the sheet inlet2, onto the processing tray521is started (step S4).

More specifically, when the sheet detection sensor93detects that a rear end of the sheet S has passed through the carry-in roller pair54, the postprocessing controller10(seeFIG.2) instructs the tapping member53to tap the rear end of the sheet S so as to achieve alignment of the sheet S along the processing tray521, followed by moving the paddle holder56downward to a specified extent. As a result of this, the alignment paddle57is moved to an acting position, coming into contact with the top face of the sheet S. In this state, the alignment paddle57is turned, causing the sheet S to be pulled in the alignment direction (arrow B direction) along the processing tray521.

Thereafter, the sheet S is conveyed further to a downstream side in the alignment direction by the alignment paddle57, aligned in the sheet widthwise direction by the width-restricting members523(seeFIG.3), and aligned and loaded in the carry-in direction by the reference plates73.

The postprocessing controller10counts carry-in count of sheets S that are carried in onto the processing tray521(step S5). Then, each time one sheet S (or specified number of sheets S) is carried in, the postprocessing controller10makes a halt position of the paddle holder56shifted upward so that the acting position of the alignment paddle57is shifted upward continuously.

Next, the postprocessing controller10decides whether or not a specified number of sheets S have been carried in onto the processing tray521(step S6). When the specified number of sheets S have not been carried in (NO at step S6), the processing flow returns to step S5, continuing carry in of sheets S onto the processing tray521and count of carried in sheets S.

When the specified number of sheets S have been carried in (YES at step S6), the postprocessing controller10transmits a control signal to the stapling-part driving motor M1(seeFIG.3) so as to make the stapling part71moved to a specified stapling position. After the stapling part71has been moved to the specified stapling position, the postprocessing controller10transmits a control signal to the stapling part71so as to make the stapling process executed on a plurality of sheets S aligned by the reference plates73(step S7).

Next, the postprocessing controller10makes the first discharge roller pair42put into mutual contact (nip formation) and moreover rotated in the discharge direction. As a result of this, a bundle of sheets S subjected to the stapling process is discharged onto the first discharge tray43(seeFIG.2for both members42,43) (step S8). In this case, the postprocessing controller10makes each support member58moved to the retractive position before the rear end of the bundle of sheets S passes through the first discharge roller pair42(step S9). After the bundle of sheets S has been discharged, the postprocessing controller10transmits a control signal to the stapling-part driving motor M1so as to make the stapling part71moved to a standby position.

Thereafter, the postprocessing controller10decides whether or not the stapling process has been ended (step S10). When the stapling process is continuing (NO at step S10), the processing flow returns to step S3, followed by repetition of: movement of each support member58from the retractive position to the projective position; carry in of the sheet S onto the processing tray521plus count of carried in sheets; execution of the stapling process; discharge of the sheet bundle; and movement of each support member58from the projective position to the retractive position (steps S3to S10). When the stapling process has been ended (YES at step S10), on the other hand, the processing is ended as it is.

According to the control example shown inFIG.7, the projective position of each support member58is determined as an optimum one based on the sheet S output information. Therefore, it becomes practicable to stably carry in and align the sheet S onto the processing tray521without being affected by type of the sheet S, by ink quantity involved in image recording by an inkjet recording apparatus, or by sheet S conveyance speed and conveyance interval.

Further, by continuously varying the projective position of each support member58in response to the output information of the sheet S, the projective position of the support member58can be set to an optimum position responsive to the type of the sheet S as well as to ink quantity, conveyance speed and conveyance interval of the sheet S. Accordingly, even when a sheet S of large conveyance load is carried or when the sheet S is liable to curl, alignment failures of the sheet S can be effectively suppressed.

Although an embodiment of the present disclosure has been described hereinabove, yet the scope of the disclosure is not limited to this, and the disclosure may be changed and modified in various ways unless those changes and modifications depart from the gist of the invention. For example, although the postprocessing controller10automatically adjusts the projective position of each support member58on a basis of the sheet S output information in the above embodiment, yet it is also possible to allow the user to adjust the projective position (projective length) of the support member58at an arbitrary timing. An example of such a configuration is that a maintenance mode in which the projective position (projective length) of the support member58is changed over is provided in the operation panel202, allowing the user to select from among modes in response to situations (alignability) of the stapling process in the sheet stapling unit92.

Also, the above embodiment is described on an example in which sheets S stacked on the processing tray521are subjected to the stapling process by the sheet stapling unit92. However, without being limited to this, the disclosure may be such that sheets S stacked on the processing tray521are subjected to a shift discharge process or a folding process.

Also in the above embodiment, information as to type of the sheet S is entered from the operation panel202of the image forming apparatus200. However, it is also allowable that sheet S output information is automatically acquired. For example, a media sensor may be placed at an arbitrary location on a sheet conveyance path from the image forming apparatus200to the sheet postprocessing device1, in which case sheet S output information such as size, thickness, grammage, grain direction, surface smoothness, and ink quantity of the sheet S to be delivered from the image forming apparatus200into the sheet postprocessing device1can be detected by the media sensor.

For detection of the thickness of the sheet S, as an example, a laser coaxial displacement gauge for detecting a thickness of a sheet S by pinching the sheet S with two optical sensors may be used as the media sensor.

For detection of the grammage of the sheet S, a grammage sensor for measuring grammage by light transmittance to the sheet S may be used as the media sensor. In this case, since a relationship between light transmittance and grammage differs depending on the type of the sheet S, there is a need for selecting an optimum grammage conversion equation on a sheet-S type basis. Further, it is also possible to calculate a density (g/m3) of a sheet S by dividing its grammage (g/m2) by its thickness (m).

For detection of the grain direction of the sheet S, as an example, with an image pickup device used as the media sensor, a transmission image resulting when LED light is applied from back side of the sheet S under conveyance is picked up, and the picked-up transmission image is compared with reference images previously stored in the apparatus controller203to detect a grain direction of the sheet S. Otherwise, with an ultrasonic measuring device used as the media sensor, a reflected waveform resulting from application of ultrasonic waves to the sheet S may be measured and compared with reference waveforms previously stored in the apparatus controller203to detect a grain direction of the sheet S.

For detection of the surface smoothness of the sheet S, a surface property sensor for discriminating surface properties of the sheet S by using optical reflection properties may be used. Generally, sheets S of low smoothness (coarse surface) such as plain paper and matte paper manifest a reflection property of perfect diffusion. Meanwhile, sheets S of high smoothness (high glossiness) such as gloss paper manifest a mixed state of regular reflection and diffusion. The surface property sensor detects surface properties of the sheet S by utilizing those differences in reflection properties.

For detection of the type of the sheet S, a paper-type discrimination algorithm for discriminating a type of the sheet S by using density, surface property (regular reflection light, diffusion light), grammage and the like of the sheet S is used.

Furthermore, as the media sensor, a moisture content meter for detecting moisture content of the sheet S may be used to detect ink quantity of the sheet S.

Also in the above embodiment, the image forming apparatus200has been exemplified by an inkjet recording apparatus. However, electrophotographic printers and copiers are also usable as the image forming apparatus200. In this connection, in the inkjet recording system in which ink is jetted out onto the sheet S, the conveyance load of the sheet S is more likely to vary as compared to the electrophotographic system. As a consequence, the present disclosure is particularly useful for the sheet postprocessing device1to which an inkjet recording apparatus is coupled as the image forming apparatus200.

The present disclosure is applicable to a sheet discharge device for discharging sheets as well as sheet postprocessing devices and image forming apparatuses equipped with the sheet discharge device.