Patent Application
20070138731
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2005-368278, filed on December 21, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
This invention relates to a sheet post-processing apparatus for performing a post-processing operation on the sheets of paper delivered from an image forming apparatus such as a copying machine, a printer or a composite machine.
2. Description of the Related Art
Some image forming apparatuses that have been marketed in recent years are accompanied by a sheet post-processing apparatus for sorting the sheets carrying an image produced as a result of an image forming operation thereon and/or executing one or more than one post-processing processes such as stapling sheets. Such a post-processing apparatus is normally arranged downstream relative to the delivery section of the image forming apparatus main body.
A sheet post-processing apparatus for stapling sheets is typically adapted to align a plurality of sheets (a bundle of sheets) by means of an aligning means, staple them, and deliver them onto a delivery tray, where stapled bundles of sheets are laid one on the other.
In such a post-processing apparatus, a succeeding sheet is subjected to a post-processing process only after the completion of the post-processing process of the immediately preceding sheet. Additionally, the post-processing apparatus may or may not be provided with a stand-by tray arranged on the way down to the stapler for the purpose of holding the sheets of paper delivered from the image forming apparatus on a stand-by status.
Japanese Patent No. 2879969 describes a structure to be used for a stapling process. The structure of the above-cited Patent Document includes a binding means for binding the sheets of recording paper delivered from an image forming apparatus, a moving means for moving the binding means along a plurality of binding positions for binding sheets of recording paper and a position control means for controlling the position of the moving means so as to align the final binding position of the current sheets of recording paper with the starting binding position of the next sheets of recording paper.
While the structure of the above-cited Patent Document can reduce the moving distance and the moving time of the binding means, the number of the stapled sheets to be laid at a delivery tray needs to be limited because the bundles of stapled sheets of recording paper are delivery at the same binding positions and, when bundles of stapled sheets of recording paper are delivered and laid one on the other at the delivery tray, the bundles are heaped up higher at the part of the binding positions than at the remaining part of the sheets. Additionally, the above-described structure is accompanied by a drawback that a succeeding bundle of sheets that is stapled and delivered to the delivery tray forces out one or more than one uppermost bundle of sheets already delivered to the delivery tray.
Jpn. Pat. Appln. Laid-Open Publication No. 2000-177921 describes a post-processing apparatus. In the apparatus described in the above-cited Patent Document, a pair of aligning members is arranged in a direction perpendicular to the conveyance direction of conveying sheets with a predetermined gap separating them and adapted to align sheets of a bundle. The alignment position for aligning sheets for bundles by means of the aligning members is shifted from bundle to bundle before the bundles of aligned sheets are delivered to a stack tray.
Thus, the post-processing apparatus of the above-cited Patent Document is designed to shift bundles of sheets from bundle to bundle instead of moving the stack tray in a direction perpendicular to the conveyance direction of conveying sheets of paper.
Jpn. Pat. Appln. Laid-Open Publication No. 2001-220055 described a sheet processing apparatus. In the apparatus described in this patent document, a pair of aligning members (side stoppers) is arranged in a direction perpendicular to the conveyance direction of conveying sheets with a predetermined gap separating them and adapted to align sheets of a bundle.
For binding a bundle of sheets at two positions by means of the sheet processing apparatus, the stapler is moved to the second stapling position after binding the bundle of sheets at the first stapling position. When the stapler is moved toward the second position, the side stoppers are moved in the direction opposite to the moving direction of the stapler so as to reduce the moving distance of the stapler.
However, with either of the apparatus described in Jpn. Pat. Appln. Laid-Open Publication No. 2000-177921 and Jpn. Pat. Appln. Laid-Open Publication No. 2001-220055, the stapled positions of some of the bundles of sheets can be aligned to heap up the bundles higher at the part of the binding positions than at the remaining part of the sheets. Additionally, a succeeding bundle of sheets that is stapled and delivered to the stack tray can force out one or more than one uppermost bundle of sheets already stored on the stack tray.
Therefore, the present invention provides a sheet post-processing apparatus that can reduce the risk of collapsing the heap of bundles of sheets of paper on a delivery tray by shifting the bound positions of an upper bundle of sheets from those of a lower bundle of sheets when delivering those bundles to the delivery tray and lay them one on the other after a stapling process.
Throughout this description, the embodiments and examples shown should be considered as exemplars, rather than limitations on the apparatus of the present invention.
Now, a preferred embodiment of the present invention will be described in detail by referring to the accompanying drawings. Throughout the drawings, the same parts are denoted by the same reference symbols and will not be described repeatedly.
The configuration and the operation of each part shown in
As shown in
The sheet P discharged from the pair of delivery rollers 6 of the image forming apparatus 5 is received by an entrance roller pair 22 arranged near the sending-in entrance of the sheet post-processing apparatus 7. The entrance roller pair 22 includes an upper roller 22a and a lower roller 22b. The entrance roller pair 22 is driven by a motor 26 (
A gate G is arranged at the downstream side of the entrance roller pair 22. The gate G sorts the sheets P received by the entrance rollers 22 into two paths (flows) The gate G shows a wedge-shaped cross section and the narrow end of the wedge is directed to the entrance rollers 22. The gate G is rotatably supported by a lateral wall section in the sheet post-processing apparatus 7. The gate G is adapted to selectively take a first position where the narrow end thereof is directed to the upper entrance roller 22a or a second position where the narrow end thereof is directed to the lower entrance roller 22b.
The first position is to be used to select the path for sheets P that require post-processing, whereas the second position is to be used to select the path for sheets P that does not require any post-processing.
When the gate G is at the first position, each sheet P is supplied to the first sheet feeding roller pair 24 and then from the first sheet feeding roller pair 24 to the stand-by tray 10. A paper path ceiling 36 (
The stand-by tray 10 receives a plurality of sheets P and lays them one on the other there until the ongoing processing at the processing tray 12 ends. The processing tray 12 aligns and supports the laid sheets P until the end of the ongoing stapling process at the stapler 14, which is a processing mechanism for post-processing.
As a predetermined number of sheets are stacked in the stand-by tray 10, the tray members 10a, 10b are opened by a motor 34 (
As shown in
The processing tray 12 has a pair of longitudinal alignment rollers 38a, 38b as shown in
The upper and lower longitudinal alignment rollers 38a, 38b are also used to pinch the stapledbundleof sheets T between them and take it out from the stapler 14 after the stapling process. The longitudinal alignment roller 38a is driven by motor 40, whereas the longitudinal alignment roller 38b is driven by motor 42.
For the sheets P that falls so as to be supplied to the processing tray 12, a rotatable paddle 44 is arranged at the position where the rear ends of the sheets P are placed. The paddle 44 is adapted to longitudinally align the uppermost sheet P of the sheets that are laid on the processing tray 12.
As shown in
A stopper 45 is arranged at the end of the processing tray 12 located at the side of the stapler 14 so as to contact the rear ends of the sheets P and regulate the positions of the rear ends. A conveyor belt 50 is arranged substantially at the center of the processing tray 12. The conveyor belt 50 is adapted to convey the bundle of sheets T that has been subjected to a stapling process and taken out from the stapler 14 by the longitudinal alignment rollers 38a, 38b to either the first delivery tray 16 or the second delivery tray 18. A feed claw 50a for hooking the rear end of the bundle of sheets T is fitted to the conveyor belt 50.
While the stand-by tray 10 can fall and supply sheets P to the processing tray 12, it can also be used to convey sheets P either toward the first delivery tray 16 or toward the second delivery tray 18. More specifically, when sheets P are conveyed toward the delivery tray 16 or toward the delivery tray 18, the rotary roller pair 28 for aligning sheets P is brought into contact with the sheets P laid on the stand-by tray 10. The rotary roller pair 28 is controlled for its vertical movement by a drive source 30 and driven to rotate by a motor 32 (
As shown in
Thus, when receiving sheets P, the first delivery tray 16 or the second delivery tray 18 that is selected is raised or lowered substantially to the height of the processing tray 12 to align the sheets P discharged onto it better. The first delivery tray 16 or the second delivery tray 18 that is selected is so arranged as to show an angle of inclination θ2 so as to support sheets P in a condition where the front ends of the sheets P are found above the respective rear ends thereof.
As shown in
The stand-by tray 10 is driven to slide by a motor 34 (
When the gate G is at the second position as shown in
The motors 26, 32, 34, 40, 42, 46 and 48 for driving the above-described various mechanisms and the drive sections 49 and 52 are driven and controlled by a control circuit (not shown).
Now, the operation of the sheet post-processing apparatus 7 will be described in terms of the flow of sheets. As a sheet P on which an image is formed by the image forming apparatus 5 is supplied form the delivery roller pair 6, the sheet post-processing apparatus 7 operates differently depending on (1) when the sheet P is not to be subjected to post-processing, (2) when the sheet P is to be subjected to post-processing and the post-processing of the preceding sheet P has not been completed and (3) when the sheet P is to be subjected to post-processing and the post-processing of the preceding sheet P has been completed.
Firstly, (1) when the sheet P is not to be subjected to post-processing, the narrowed part of the wedge-shaped gate G is positioned to substantially point the lower entrance roller 22b. The sheet P delivered from the entrance roller pair 22 is supplied to the second sheet feeding roller pair 60 and then further to the third sheet feeding roller pair 61. The sheet P that is fed out from the third sheet feeding roller pair 61 is delivered to the fixed tray 19 on the top surface of the sheet post-processing apparatus.
Now, (2) when the sheet P is to be subjected to post-processing (a stapling process) and there is no preceding sheet P on the processing tray 12, the stand-by tray 10 is driven to slide in the direction of arrow m or arrow n to either of the positions indicated by dotted lines, where it drops the sheet P. The transversal alignment plates 47a, 47b are arranged so as to show a gap between them substantially equal to the width of the sheet P in order to transversally align the dropping sheet P. Then, as a result, the sheet P supplied by the sheet feeding roller pair 24 is directly dropped onto the processing tray 12 without being obstructed by the stand-by tray 10 on the way.
When the sheet P is dropped, the longitudinal alignment roller pair 38a is retreated upwardly and the receiving section 44a of the paddle 44 receives the sheet P at the rear end of the sheet P. The sheet P falls as its two lateral sides are guided by the transversal alignment plates 47a, 47b so as to be aligned in the transversal direction. Thereafter, the paddle 44 is driven to rotate in the sense as indicated by arrow o in
Additionally, the paddle 44 sends out the sheet P in the direction of arrow q by means of its feed section 44c until the rear end of the sheet P contacts the stopper 45 to complete the operation of longitudinally aligning the sheet P. Note that the longitudinal alignment roller 38a may be driven to move up and down each time a sheet P is delivered to it in order to perform the operation of longitudinally aligning the sheet P on the processing tray 12.
Thus, the sheet P on which an image is formed is directly laid on the processing tray 12 from the sheet feeding roller pair 24 while it is sequentially aligned transversally and longitudinally. As the number of sheets P on the processing tray 12 gets to a predetermined level, the sheets P on the processing tray 12 is stapled by the stapler 14 at one or more than one desired positions to form a bundle of sheets T.
Thereafter, the bundle of sheets T is pinched by the longitudinal alignment roller 38a that is driven to rotate in the sense of arrow r and the longitudinal alignment roller 38b that is driven to rotate in the sense of arrow s in
As the rear end of the bundle of sheets T passes the longitudinal alignment rollers 38a, 38b, it is hooked by the feed claw 50a of the conveyor belt 50 that is driven to rotate in the sense of arrow t in
Since the first delivery tray 16 is arranged with an angle of inclination θ2 and hence the front ends of the sheets P are found above the respective rear ends thereof, the preceding sheet P delivered onto the first delivery tray 16 would not be pushed out if the rear end of the preceding sheet P touches the front end of the succeeding bundle of sheets T.
If the sheets of the preceding bundle of sheets T are misaligned by the succeeding sheet P, the bundle of sheets T falls by its own weight and hence is laid on the first delivery tray 16 with the rear ends of the sheets aligned with each other because of the angle of inclination θ2. In other words, the delivered sheets P are sequentially laid on the first delivery tray 16 in the proper order to complete the process of stapling the sheets P.
Thus, sheets are sequentially laid on the first delivery tray 16 in the above-described manner. As pointed out above, the first delivery tray 16 is made to show an angle of inclination of θ2 and hence the front ends of the sheets P on it are found above the respective rear ends thereof. Therefore, if a sheet P is curled to raise a middle part from the other parts thereof when delivered onto the first delivery tray 16 and its front end touches the preceding sheet P laid on the first delivery tray 16, the preceding sheet P would not be pushed out by the succeeding curled sheet P. In other words, the delivered sheets P are sequentially laid on the first delivery tray 16 in the proper order.
Finally, the instance (3) when the sheet P is to be subjected to post-processing and there are preceding sheets P remaining on the processing tray 12 because the stapling process that is being executed on them has been completed will be described below.
In this condition, the tray members 10a, 10b are driven to slide respectively from the positions indicated by dotted lines in the directions opposite to arrows m and n to get to the positions indicated by solid lines in
The second and subsequent sheets P laid on the stand-by tray 10 fall onto the stand-by tray 10 and then are sent toward the stoppers 10c, 10d by the rotary roller pair 28 that is driven to rotate in the sense opposite to that of arrow f in
In this way, the supplied sheets P are sequentially laid on the stand-by tray 10 in the proper order. If a preceding sheet P is pushed by a succeeding sheet P and slightly misaligned, the preceding sheet P falls to the position where its rear end contacts the stoppers 10c, 10d because of the angle of inclination θ1. Thus, the rear ends of the sheets P that are laid on the stand-by tray 10 are held to an aligned state.
Meanwhile, as the preceding sheets P on the processing tray 12 are discharged toward the first delivery tray 16 and the processing tray 12 is ready for receiving the succeeding sheets P, the tray members 10a, 10b of the stand-by tray 10 are driven to slide respectively in the direction of arrow m and the direction of arrow n from their positions indicated by solid lines to the positions indicated by dotted lines by way of the positions indicated by dotted chain lines in
Then, as the tray members 10a, 10b get to the respective positions indicated by dotted chain lines in
The lower sheet P of the two sheets that are made to fall on the processing tray 12 is sent in the direction of arrow q by the longitudinal alignment roller 38b that is driven to rotate in the sense opposite to that of arrow s in
On the other hand, the upper sheet P of the two sheets that are made to fall on the processing tray 12 is sent in the direction of arrow q by the longitudinal alignment roller 38a that is driven to rotate in the sense opposite to that of arrow r in
Then, the third and subsequent sheets P discharged from the image forming apparatus 5 are made to fall directly from between the tray members 10a, 10b to the processing tray 12 without held to a stand-by status on the stand-by tray 10. The third and subsequent sheets P are sequentially aligned on the sheets P that have been laid on the processing tray 12 by the paddle 44.
When the number of sheets P laid on the processing tray 12 gets to a predetermined level, a bundle of sheets T is formed by the stapler 14 by way of a stapling process. Thereafter, the bundle of sheets T is conveyed toward the first delivery tray 16 by the longitudinal alignment rollers 38a, 38b and hooked by the feed claw 50a of the conveyor belt 50 at the rear end thereof so as to be put on the first delivery tray 16 as shown in
The overall operation of the sheet post-processing apparatus 7 is described above. Now, the configuration of the stapling process section that characterized the present invention will be described below.
Generally, sheets are stapled at a corner or at a plurality of (e.g., two) positions along an edge of the sheets. When sheets are stapled at a plurality of positions, bundles of sheets T are stacked on the delivery tray 16 and the staples are laid one on the other at staple positions ST to heap up as shown in
A sheet post-processing apparatus according to the invention is characterized in that it can prevent staples from being laid one on the other to form a heap. Then, it is possible to prevent the stack of bundles of sheets on the stack tray from collapsing.
Meanwhile, the stapler 14 is driven to slide along an edge of the sheets P by the staple drive section 49 in the direction of u and stops at the first staple position a1 for a stapling operation of the stapling process. Then, the stapler 14 is further driven to slide along the edge of the sheets P in the direction of arrow A1 and stops at the second staple position a2 for another stapling operation of the stapling process.
In this way, the stapler 14 is driven to move and stops at a plurality of positions for the stapling process. As the stapling process at the first and second staple positions ends, the sheets P are conveyed toward the delivery tray 16 (or 18) by the conveyor 50. Note that the gap L1 separating the first staple position a1 and the second staple position a2 is about 120 mm.
As the stapled bundle of sheets is discharged, the transversal alignment plates 47a, 47b are driven to move to a slight extent in a direction perpendicular to the moving direction of the sheets relative to the first alignment position as shown in
The stapler 14 is driven to move from the above-described second staple position a2 by a predetermined distance L2 in the direction in which the transversal alignment plates 47a, 47b have been moved (the direction indicated by arrow A2) and stops at the third staple position A3 for a stapling operation of the stapling process. Then, the stapler 14 is driven to move distance L1 in the opposite direction (the direction indicated by arrow A3) along an edge of the sheets P and stops at the fourth staple position a4 for another stapling operation of the stapling process.
In this way, the stapler 14 is driven to move in the opposite direction and stops at a plurality of positions for the stapling process. Since the sheets P are aligned at a position that corresponds to the distance by which the transversal alignment plates 47a, 47b are moved, they are stapled always at the right positions.
As the stapling operations at the third and fourth staple positions a3, a4 are completed, the sheets P are conveyed to the delivery tray 16 (or 18) by the conveyor belt 50 and the transversal alignment plates 47a, 47b return to the respective first alignment positions b1, b2 to align the next bundle of sheet P that are brought in while the staple 14 is driven to slide by the staple drive section 49 and returns to the first staple position a1. The above cycle is repeated for the stapling process to progress.
Thus, the bundles of sheets T discharged to the delivery tray 16 (or 18) are placed zigzag vertically but stapled at the same positions so long as the sheets have the same size. In other words, the staples gap of a preceding bungle of sheets T and those of the immediately succeeding bundle of sheets T that are discharged onto the delivery tray 16 are separated by a constant gap.
In the above-described operation of the stapler 14, the distance L1 from the first staple position a1 to the second staple position a2, which is equal to the distance from the third staple position a3 to the fourth staple position a4, is defined by the gap between the sheet-binding positions, which is about 120 mm.
The distance L2 from the second staple position a2 to the third staple position a3 may be appropriately selected so as to differentiate the staple positions ST at the first alignment position and the staple positions ST at the second alignment position. For instance, about 15 mm may be sufficient for the distance L2. Similarly, about 15 mm may be sufficient for the distance L2 from the fourth staple position a4 to the first staple position a1.
In this way, the stapler 14 is driven to move cyclically along the staple positions a1→a2→a3 and along the staple positions a3→a4→a1 according to the alignment positions of the alignment plates 47a, 47b. The moving distance of the stapler 14 can be reduced for each cycle if the moving distance L2 is defined to be not greater than L1/2 for instance. Then, the moving time can be reduced to realize a high speed stapling process.
As shown in
As described above, according to the present invention, it is possible to minimize the problem that a succeeding bundle of sheets that is stapled and discharged to the delivery tray 16 (or 18) can force out one or more than one uppermost bundle of sheets already discharged to the delivery tray to collapse the stack. Thus, a sheet post-processing apparatus according to the present invention does not reduce the efficiency of the corresponding image forming apparatus and hence is convenient to the users.
The present invention is by no means limited to the above-described embodiment, which may be modified and altered in various different ways without departing from the scope of the invention as defined in claims. For example, while the stapler 14 staples each bundle of sheets at two positions but it may alternatively staple at three positions.
Although exemplary embodiments of the present invention have been shown and described, it will be apparent to those having ordinary skill in the art that a number of changes, modifications or alternations to the invention as described herein may be made, non of which depart fro the spirit of the present invention. All such changes, modifications and alterations should therefore be seen as within the scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-368278 | Dec 2005 | JP | national |
