This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2005-380565, filed on December 29, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a sheet post-processing apparatus and a sheet post-processing method that perform post-processing for a sheet discharged from an image forming apparatus such as a copier, a printer, or a composite device.
2. Description of the Related Art
In recent years, there is developed a sheet post-processing apparatus which is disposed adjacent to the sheet discharge section of an image forming apparatus main body for the purpose of performing post-processing, such as sorting and stapling, for a sheet on which an image has been formed in the image forming apparatus. For example, in a post-processing apparatus that performs stapling processing, a plurality of sheets (sheet bundle) are aligned by an alignment means and stapled and, after that, fed to a sheet discharge tray to sequentially be loaded thereonto.
Such a sheet post-processing apparatus performs post-processing for a succeeding sheet after completion of the post-processing for a preceding sheet. Although the stapled sheet bundle is discharged onto the sheet discharge tray, the sheet alignment performance may deteriorate or the sheet may be folded at the time of discharge in some cases depending on the size, quality, stiffness or thickness of the sheet to be processed.
Jpn. Pat. Appln. Laid-open Publication No. 2004-155551 discloses a sheet discharge apparatus. The sheet discharge apparatus in this disclosure is featured in the configuration of a sheet discharge table, in which ingenuity has been applied thereto to prevent the discharged sheets from being disturbed. However, this disclosure does not cope with the deterioration of the sheet alignment performance due to a difference in the sheet type.
An object of the present invention is to provide a sheet post-processing apparatus and a sheet-post processing method capable of preventing the sheets discharged onto a sheet discharge tray from being disturbed to thereby enhancing the sheet alignment performance.
Throughout this description, the embodiments and examples shown should be considered as exemplars, rather than limitations on the apparatus of the present invention.
Hereinafter, an embodiment of the present invention will be described in detail. In the following description, the same reference numerals denote the same parts through the drawings, and the overlapped description is omitted.
Concrete configurations and operations of respective components shown in
A sheet P on which an image has been formed in an image forming apparatus 5 such as copier is fed by a pair of sheet discharge rollers 6 to a sheet post-processing apparatus 7. As shown in
The sheet P fed by the pair of sheet discharge rollers 6 of the image forming apparatus 5 is received by a pair of entrance rollers 22 provided near the entrance of the sheet post-processing apparatus 7. The entrance rollers 22 have an upper roller 22a and lower roller 22b and are driven by a motor 26 (refer to
A gate G for dividing the feeding path of the received sheet P into two feeding paths is provided on the downstream side of the entrance rollers 22. The gate G has a wedge-shaped cross section and its sharpened end is directed to the entrance rollers 22 side. The gate G is pivotably fitted to the side wall portion of the sheet post-processing apparatus 7, so that the sharpened end can be positioned at both first and second positions respectively pointing the upper entrance roller 22a and lower entrance roller 22b. The first position is selected in the case where post-processing needs to be applied to the sheet P, while the second position is selected in the case where post-processing need not be applied to the sheet P.
When the gate G is positioned at the first position, the sheet P is fed by first sheet feed rollers 24 to the standby tray 10. Between the entrance rollers 22 and standby tray 10, a paper path ceiling 36 for leading the sheet P to the sheet feed rollers 24 is installed. The sheet feed rollers 24 have an upper sheet feed roller and lower sheet feed roller. The standby tray 10 temporarily receives and loads the sheet P until post-processing applied to a plurality of sheets P on the processing tray 12 has ended.
Under the standby tray 10, a processing tray 12 for loading the sheets P dropped and supplied from the standby tray 10 is arranged. The processing tray 12, while the sheets P are stapled by the stapler 14 which is a post-processing mechanism for performing post-processing, supports the loaded sheets P in an aligned state.
As shown in
As shown in
The vertical alignment rollers 38a and 38b serve also as bundle conveyer rollers that hold and take out stapled sheet bundle T from the stapler 14. The vertical alignment roller 38a is driven by a motor 40 and vertical alignment roller 38b is driven by a motor 42. At the position where the rear end of the sheet P which is dropped and supplied onto the processing tray 12 is dropped, a paddle 44 is arranged. The paddle 44, which is configured to be rotatable, aligns vertically the uppermost sheet P loaded on the processing tray 12.
The paddle 44, as shown in
At the end of the processing tray 12 on the side of the stapler 14, a stopper 45 that is brought into contact with the rear end of each of the sheets P and thereby restricts the rear end position is arranged. Almost at the center of the processing tray 12, a conveyor belt 50 is installed. The conveyer belt 50 feeds the sheet bundle T, which is stapled and taken out from the stapler 14 by the upper and lower vertical alignment rollers 38a and 38b, up to first or second sheet discharge tray 16 or 18. To the conveyer belt 50, a feed pawl 50a for hooking the rear end of the sheet bundle T is attached.
The standby tray 10 can drop and supply the sheet P onto the processing tray 12 and further can be used to feed the sheet P to the first or second sheet discharge tray 16 or 18. When the sheet P is to be fed to the sheet discharge tray 16 or 18, rotating rollers 28 for aligning the sheet P is brought into contact with the sheet P on the standby tray 10. The rotating rollers 28 are controlled by a standby tray roller drive source 30 in terms of their vertical movement and rotated by a motor 32 (refer to
As shown in
As shown in
The standby tray 10 slides and moves by the motor 34 (refer to
The motors 26, 32, 34, 40, 42, 46, and 48 that drive the abovementioned mechanisms and the drive sections 49 and 52 are controlled by a control circuit.
Next, the operation of the sheet post-processing apparatus 7 will be described in line with the flow of the sheet. Although the sheet to which post-processing has been applied can be discharged onto the first or second sheet discharge trays 16 or 18, it is assumed hereinafter that the sheet is discharged onto the first sheet discharge tray 16 for the sake of simplification.
Firstly, a case where the post-processing is not to be performed will be described. When the sheet P on which an image has been formed in the image forming apparatus 5 is supplied by the sheet discharge roller 6, the first sheet discharge tray 16 slides and moves to the position indicated by a dotted line shown in
In this case, the gate G is positioned at the first position, and the sheet P fed from the entrance rollers 22 through the paper path ceiling 36 is fed toward the standby tray 10 by the sheet feed rollers 24. The sheet P is then dropped down onto the standby tray 10, fed by the rotating rollers 28 rotated in the direction of the arrow f, and is discharged onto the sheet discharge tray 16.
Next, a case where the post-processing (stapling processing) is to be performed and no preceding sheets P in execution of the staple processing remain on the processing tray 12 will be described. The gate G is positioned at the first position, and the standby tray 10 slides and moves the tray members 10a and 10b respectively in the directions of arrows m and n of
At the time of dropping and supplying the sheet P, the upper vertical alignment roller 38a is shifted upward, and the receiving portion 44a of the paddle 44 receives the rear end of the sheet P. Both sides of the sheet P drop in contact with the horizontal alignment plates 47a and 47b and are aligned in the horizontal direction. Then, the paddle 44 rotates in the direction of the arrow o in
In this way, the sheet P on which an image has been formed is loaded directly on the processing tray 12 from the sheet feed rollers 24 while sequentially being aligned in the horizontal direction and vertical direction. When the sheets P reach a predetermined number, the stapler 14 staples the sheets P on the processing tray 12 at a desired position and bundles them to form the sheet bundle T. Thereafter, as shown in
When the rear end of the sheet bundle T passes the upper and lower vertical alignment rollers 38a and 38b, it is hooked by the feed pawl 50a of the conveyor belt 50 rotated in the direction of the arrow t in
The first sheet discharge tray 16 is arranged in a tilt angle θ2 and therefore the front end of the sheet P is positioned higher than the rear end thereof, so that the sheet P is sequentially loaded on the sheet discharge tray 16 unless the order is disturbed.
Next, a case where the staple processing is to be performed and preceding sheets P in execution of the staple processing remain on the processing tray 12 will be described. At this time, the standby tray 10 slides and moves the tray members 10a and 10b respectively in the opposite direction of the direction of the arrow m and in the opposite direction of the direction of the arrow n in
The second and subsequent sheets P loaded on the standby tray 10 are fed to the standby stoppers 10c and 10d side by the rotating rollers 28 rotated in the opposite direction of the direction of the arrow f in
During this period, when the preceding sheet P on the processing tray 12 is discharged on the side of the sheet discharge tray 16 and the processing tray 12 becomes free, the standby tray 10 slides and moves the tray members 10a and 10b respectively in the directions of the arrows m and n in
By doing this, for example, two sheets P standing by on the standby tray 10 are dropped and supplied onto the processing tray 12 from between the tray members 10a and 10b. Thereafter, the sheets P dropped from the standby tray 10 are controlled on both sides by the horizontal alignment plates 47a and 47b and are aligned horizontally. Then, as described in
When the sheets P loaded on the processing tray 12 reach a predetermined number, the sheets P are stapled by the stapler 14 to form a sheet bundle T. Thereafter, the sheet bundle T is fed toward the sheet discharge tray 16 by the upper and lower vertical alignment rollers 38a and 38b. Further, the rear end of the sheet bundle T is hooked by the feed pawl 50a of the conveyor belt 50 and is sent to the sheet discharge tray 16. Thereafter, the sheet bundle T is discharged onto the sheet discharge tray 16 by the discharge rollers 38c.
The entire operation of the sheet post-processing apparatus 7 has been described. Next, a configuration of the sheet discharge section for discharging the sheet to the sheet discharge tray 16, which is the feature of the present invention will be described.
As shown in
A reference numeral 82 denotes a control circuit for controlling the sheet post-processing apparatus 7. The control circuit 82 is constituted by a microprocessor including, e.g., a CPU and communicates with the control circuit 81 of the image forming apparatus 5 so as to allow operations of the image forming apparatus 5 and sheet post-processing apparatus 7 to work together.
The control circuit 82 further controls a drive motor 83 provided in a sheet discharge tray drive section 52 and a drive motor 84 that rotates the conveyer belt 50. To the conveyer belt 50, the feed pawl 50a for hooking the rear end of the sheet bundle T is attached. When the conveyer belt 50 is rotated, the feed pawl 50a feeds the sheet bundle T to the sheet discharge port 70. To the control circuit 82, a detection result from the sensor 71 is input.
In the case where the A4 sheet having a normal thickness is selected, the flow then advances to step S3 where discharge operation of the sheet bundle T is started to rotate the conveyer belt 50. Accordingly, the feed pawl 50a feeds the sheet bundle T to the discharge port 70, and the sheet discharge operation is completed in step S4. At this time, the sheet discharge tray 16 is positioned at a previously set first height position H1 for receiving the A4 sheet having a normal thickness and then receives the discharged sheet bundle T and stores it.
Subsequently, the sheet discharge tray 16 starts moving to go down once in step S5 and then goes up in step S6. Then, in step S7, the sensor 71 detects the upper surface of the sheet bundle T discharged onto the sheet discharge tray 16, and, in step S8, the sheet discharge tray 16 is moved down such that the upper surface of the sheet bundle T is positioned at the first height position H1. The sheet discharge tray 16 stands by at this position. This standby position is set as A.
In the case where the A4 sheet having a reduced thickness has been detected in step S2, the flow advances to step S9, where the sheet discharge tray 16 is moved up to a second height position H2. The second height position H2 is higher than the first height position Hi and positions immediately below the sensor 71.
In step S10, discharge operation of the sheet bundle T is started to rotate the conveyer belt 50. Accordingly, the feed pawl 50a starts feeding the sheet bundle T to the sheet discharge port 70. After that, in step S11, the sheet discharge tray 16 is moved down so that the feed pawl 50a does not collide with the sheet discharge tray 16.
Subsequently, in step S12, the sheet discharge tray 16 is moved up once again and receives the discharged sheet bundle T and stores it. After the discharge operation of the sheet bundle T has been completed in step S13, the sensor 71 detects the upper surface of the sheet bundle T in step S14. Thus, in step S15, the sheet discharge tray 16 is stopped at the position where the upper position of the sheet bundle T is positioned at the second height position H2 and stands by at this position. This standby position is set as B.
Although a case where the sheet bundle T is stored in the sheet discharge tray 16 has been described in this example, the same operation is applied also to a case where the sheet is discharged one by one.
The above operation of the sheet discharge section shown in the flowchart is shown in
As shown in
As described above, the A4 sheet having a normal thickness has comparatively a large stiffness and therefore difficult to be curled. Since the sheet is difficult to be curled even if it is received at the first standby position H1, the sheets P loaded on the sheet discharge tray 16 are less disturbed.
Also in the case where a sheet having a larger size in the sheet discharge direction, such as an A4-R, A3, or LT-R size sheet is to be processed, the sheet may be received at the first standby position H1. Such a sheet has a large length and the front end of the discharged sheet reaches the surface of the sheet discharge tray 16 before it is curled (refer to
On the other hand, as shown in
The sheet curling characteristics are determined not only depending on the sheet thickness but also sheet quality. For example, an LT (letter) size sheet which is commonly used in United States is easy to be curled. Therefore, when the LT has been selected on the operation section 72, it is determined that the sheet easy to be curled has been selected, and the sheet is received at the second height position H2, thereby reducing the curl of the sheet. Further, sheet alignment performance on the sheet discharge tray 16 can be enhanced.
Further, a small-size sheet, such as a B5 sheet is easy to be curled. Therefore, in the case where the small-size sheet is to be processed, the sheet should be received at the second standby position H2.
Although the sheet type is determined based on the operation made to the operation section 72 in the above embodiment, in the case where the image forming apparatus 5 and a PC (Personal Computer) are connected to each other through a network and the image forming apparatus 5 is used to print a document or the like created on the PC, a configuration may be adopted in which the specification state of the sheet from the PC is sent to the image forming apparatus 5 and, based on it, the sheet type is determined.
As described above, according to the present invention, the position of the sheet discharge tray is controlled depending on the sheet type when the sheet is discharged onto the sheet discharge tray and thereby it is possible to provide a sheet post-processing apparatus capable of preventing the sheet from being curled, preventing the sheets loaded on the sheet discharge tray from being disturbed, and achieving good sheet alignment performance.
The present invention is not limited to the above embodiment and various modifications are possible within the scope of the invention. For example, the post-processing is not limited to the staple processing, but may be other processing such as hole-punching processing in sheets.
Although an exemplary embodiment of the present invention has been shown and described, it will be apparent to those having ordinary skill in the art that a number of changes, modifications, or alterations to the invention as described herein may be made, none of which depart from the spirit of the present invention. All such changes, modifications, and alternations should therefore be seen as within the scope of the present invention.
Number | Date | Country | Kind |
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2005-380565 | Dec 2005 | JP | national |