Patent Application
20170205751
Field of the Invention
This invention relates to a post-processing device and an image forming apparatus equipped with the post-processing device. More specifically, this invention relates to a post-processing device which folds a sheet and an image forming apparatus equipped with the post-processing device.
Description of the Related Art
As electrophotography image forming apparatuses, there are an MFP (Multi Function Peripheral) having a scanner function, a facsimile function, a copying function, a function of a printer, a data transmitting function and a server function, a facsimile device, a copying machine, a printer, and so on.
Post-processing devices which perform post-processing on a sheet printed by an image forming apparatus are known. A post-processing device is normally installed on an image forming apparatus. A post-processing device can perform a saddle stitching and a half-folding process on a plurality of sheets at the central part, a Z-folding process for folding a large sized page into a Z shape, a process for punching sheets, a process for stapling sheets, and so on.
Conventional folding devices are disclosed in the below Documents 1 to 3, for example. The below Document 1 discloses a Z-folding device comprises of a pair of conveying rollers, a second pair of folding rollers, and a first pair of folding rollers. The pair of conveying rollers is provided on the first conveying path which feeds a sheet to a process tray. The second pair of folding rollers is provided at a downstream side of the pair of conveying rollers, and forms the second folding line on a sheet on which Z-folding is to be performed. The first pair of folding rollers is provided on the second conveying path, wherein the second conveying path is branched from the first conveying path between the pair of conveying rollers and the second pair of folding rollers. The first pair of folding rollers forms the first folding line on a sheet on which the Z-folding is to be performed.
The below Document 2 discloses a sheet processing device comprises a stacking feeding paper path which stores conveyed sheets, a butting part for positioning the stored sheets on the stacking feeding paper path by supporting the end of the sheets in the conveying direction, a folding roller for forming a folding line in the width direction perpendicular to the sheet conveying direction by holding the sheet by a nip portion, and a hold unit for holding the sheets which were stored on the stacking feeding paper path and were supported by the butting part and feeding the sheets to the nip portion of the folding roller.
The below Document 3 discloses a sheet folding device comprises a first pair of folding rollers which makes a first folding line on a sheet, a second pair of folding rollers which makes a second folding line on the sheet, a first stopper part for positioning the conveyed sheet by butting the leading end of the conveyed sheet in the conveying direction, a second stopper part for positioning the conveyed sheet by butting the first folding line of the sheet, and a sheet press unit to assist the sheet to form a slack on the sheet and guide the slack to a nip portion the second pair of folding rollers. The sheet press unit has a contact part which makes contact with the sheet, and a supporting part which is flexible and supports the contact part swingably.
However, according to the technique described in Document 1 etc., the first pair of folding rollers faces the first conveying path. Hence, there is a risk that a sheet makes contact with the first pair of folding rollers, to cause a paper feeding defect, when a sheet on which the folding process is not performed passes through the first conveying path, or when a leading end of a sheet before the first folding line is formed is guided to the nip of the second pair of folding rollers.
This invention is to solve the above problems. The object is to provide a post-processing device which has proper paper feeding performance, and an image forming apparatus equipped with the post-processing device.
According to one aspect of this invention, a post-processing device capable of performing a first and a second folding processes on a sheet, comprises a pair of conveying rollers installed on a first conveying path for conveying the sheet, a first pair of folding rollers which is installed at a downstream side of the pair of conveying rollers on the first conveying path, for performing the second folding process on the sheet, a second pair of folding rollers which is installed on a second conveying path for conveying the sheet, which is branched from the first conveying path between the pair of conveying rollers and the first pair of folding rollers, for performing the first folding process on the sheet, and a guide part which is installed at a closure position which shuts the first conveying path, for guiding the sheet conveyed from the pair of conveying rollers to the first pair of folding rollers, wherein the closure position is a position where the guide part shuts the first conveying path against an area between a location which is a nearest location from the first conveying path on a circumference of one roller of the second pair of folding rollers and a location which is a nearest location from the first conveying path on a circumference of another roller of the second pair of folding rollers.
The above and other objects, advantages and features of the present invention will become more fully understood from the detailed description given hereinbelow and the appended drawings which are given by way of illustration only, and thus are not intended as a definition of the limits of the present invention, and wherein:
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.
In the followings, the embodiments of this invention will be explained with the FIGs.
In the following embodiments, a post-processing device which is a part of an image forming apparatus will be explained. The image forming apparatus may be an MFP, a printer, a copying machine, a facsimile, or the like. The post-processing device may be designed separating from a main body of the image forming apparatus. The post-processing device may be attachable to/detachable from the main body of the image forming apparatus, as needed basis.
Referring to
Referring to
The pair of conveying rollers 1 is placed on conveying path TR1 (an example of a first conveying path) on which sheets are conveyed. The pair of conveying rollers 1 is rotationally driven, to pinch a sheet by nip N1 and convey it along with conveying path TR1.
The pair of folding rollers 2 is placed at a downstream side of the pair of conveying rollers 1 on conveying path TR1. The pair of folding rollers 2 is rotationally driven, to pinch a sheet by nip N2 and convey it along with conveying path TR1. The pair of folding rollers 2 performs the second folding process (the 2nd folding process) on a sheet on which a Z-folding is to be performed, at nip N2.
The pair of folding rollers 3 is placed on conveying path TR2 (an example of a second conveying path). Conveying path TR2 is branched from conveying path TR1 between the pair of conveying rollers 1 and the pair of folding rollers 2. The pair of folding rollers 3 performs the first folding process (the 1st folding process) on a sheet on which a Z-folding is to be performed, at nip N3.
When performing the first folding process on a sheet on which a Z-folding process is to be performed, folding guide 4 guides the slack of the sheet to nip N3 of the pair of folding rollers 3. Folding guide 4 is movable between the evacuation position (an example of the first folding part position) and the folding position (an example of the second folding part position). The evacuation position and the folding position will be explained later in detail.
When a sheet on which a Z-folding process is not to be performed is conveyed along with conveying path TR1 or the like, movable guide 6 guides the sheet to nip N2 of the pair of folding rollers 2. When performing the second folding process on a sheet on which a Z-folding process is to be performed, movable guide 6 guides the slack of the sheet to nip N2 of the pair of folding rollers 2. Movable guide 6 is swingable (movable) around the fulcrum 6a, among the closure position, the evacuation position, and the guiding position. The closure position, the evacuation position, and the guiding position will be explained later in detail.
Sheet guide 7 guides a sheet to conveying path TR1. Sheet guide 7 has aperture 7a at the branching part of conveying path TR2 from conveying path TR1.
Sensor SE detects a sheet at a downstream side of nip N2 on conveying path TR1.
Post-processing device 51 is further equipped with fixing unit 31 to which folding guide 4 is fixed, energization part 32 installed between folding guide 4 and fixing unit 31, fixing unit 33 to which movable guide 6 is fixed, and energization part 34 installed between movable guide 6 and fixing unit 33. Post-processing device 51 drives fixing unit 31 to move folding guide 4. Post-processing device 51 drives fixing unit 33 to move movable guide 6.
In the pair of conveying rollers 1, one roller which forms the pair of conveying rollers 1 may be rotationally driven, and another roller may be driven by the one roller. Both the rollers which form the pair of conveying rollers 1 may be rotationally driven. The pairs of folding rollers 2 and 3 can be rotationally driven in the similar manner
Referring to
CPU 101 works in accordance with control programs, and controls the entirety of image forming apparatus 100.
ROM 102 stores control programs.
RAM 103 is a working memory for CPU 101, to temporarily store various data.
Scanner 104 reads document images.
Network interface 105 transmits and receives information with external devices which are connected to image forming apparatus 100, via a network (which is not shown in FIGs.).
Operation panel 106 displays various information, and receives various operations.
Subsidiary storage device 107 stores various data, such as image data to be printed.
Image forming unit 108 performs printing on sheets in the inner part of the main body 52 of the image forming apparatus. Image forming unit 108 is roughly configured with a toner image forming unit, a fixing device, a sheet conveying unit, and so on Image forming unit 108 forms an image on the sheet by electrophotographic technology, for example. The toner image forming unit synthesizes four-colored images by so-called a tandem system, to form color images on sheets. The toner image forming unit is configured with photo conductors installed for colors of C (cyan), M (magenta), Y (yellow), and K (black), an intermediate transfer belt to which toner images are transferred (the primary transfer) from the photo conductors, a transfer unit to transfer an image from the intermediate transfer belt to a sheet (the secondary transfer), and so on. The fixing device has a heating roller and a pressure roller. The fixing device pinches and conveys a sheet on which a toner image was formed, by using a heating roller and a pressure roller, to heat and apply pressure on the sheet. Herewith, the fixing device melts toner adhered to the sheet to fix it on the sheet, to form the image on the sheet. The sheet conveying unit is configured with paper feeding rollers, conveying rollers, motors to drive the rollers, and so on. The sheet conveying unit feeds paper sheets from a feeding cartridge, and conveys the sheets in the inner part of the main body 52 of the image forming apparatus. The sheet conveying unit feeds sheets printed by the main body 52 of the image forming apparatus from the main body 52 of the image forming apparatus to the inner part of post-processing device 51.
Post-processing control unit 109 controls entire behavior of post-processing device 51 under the control of CPU 101. Post-processing control unit 109 includes the pair of conveying rollers control unit 111, the pair of folding rollers control unit 112, the pair of folding rollers control unit 113, folding guide control unit 114, and movable guide control unit 115. The pair of conveying rollers control unit 111 controls rotation of the pair of conveying rollers 1. The pair of folding rollers control unit 112 controls rotation of the pair of folding rollers 2. The pair of folding rollers control unit 113 controls rotation of the pair of folding rollers 3. Folding guide control unit 114 controls behavior of folding guide 4. Movable guide control unit 115 controls behavior of movable guide 6.
Next, the behavior of post-processing device 51 according to the embodiment will be explained. In the following FIGs., a structure of a part of post-processing device 51 may be shown, only when the explanation is needed.
Referring to
When post-processing device 51 conveyed sheet SH into the inner part of folding device 40, post-processing device 51 rotates the pair of conveying rollers 1 and the pair of folding rollers 2, to convey sheet SH along with conveying path TR1. During this conveying, folding guide 4 is present at the evacuation position P41. At the evacuation position P41, leading end 4a of folding guide 4 is present at an upper side location of conveying path TR1 (the opposite side of conveying path TR1 to the pair of folding rollers 3). Movable guide 6 is present at closure position P61.
Referring to
When movable guide 6 is present at closure position P61, movable guide 6 guides the leading end of the sheet conveyed from the pair of conveying rollers 1 to the pair of folding rollers 2. When movable guide 6 is present at closure position P61, the sheet being conveyed along with conveying path TR1 is prevented from making contact with the pair of folding rollers 3, so that a feeding paper defect can be prevented.
When a Z-folding process is not performed on sheet SH, post-processing device 51 makes the pair of conveying rollers 1 and the pair of folding rollers 2 keep rotating, in the state that movable guide 6 is present at closure position P61, to discharge sheet SH onto discharge tray 21 (
Referring to
At the timing when the leading end of sheet SH arrives at the predetermined location decided in response to a size of sheet SH or a type of the folding mode, post-processing device 51 stops rotation of the pair of folding rollers 2. The location of the anterior end of sheet SH is calculated based on the clock time when sensor SE detects the anterior end of sheet SH and the conveying velocity of sheet SH. After the pair of folding rollers 2 stops, post-processing device 51 continuously drives the pair of conveying rollers 1 rotationally.
Referring to
Since the slack LP1 is formed only by feeding of the pair of conveying rollers 1, the variation of the stopping positions of sheets can be decreased, as compared with the case in which a slack is formed by feedings of both of the pair of conveying rollers 1 and the pair of folding rollers 2.
Next, under the state in which movable guide 6 is arranged at the evacuation position P62, post-processing device 51 performs the first folding process. Post-processing device 51 begins to move folding guide 4 toward the folding position P42 adjacent to nip N3, as shown by arrow AR2. Post-processing device 51 guides the slack LP1 of sheet SH to nip N3, by pushing sheet SH by using folding guide 4.
Referring to
The size of the slack LP1 before being pushed by folding guide 4 can be adjusted by time t1 as presented above. Hence, the size of the slack LP1 does not become excessively enlarged, as compared to the slack space (the space adjacent to nip N3). Therefore, creases and kinks do not occur on sheet SH, and the slack LP1 can be pushed by sufficient force of folding guide 4 at all times.
Referring to
When sheet SH is fed into nip N3, the slack LP1 enlarges, and the tension of sheet SH decreases. The energization force of energization part 32 becomes larger than the tension of sheet SH, and energization part 32 returns to the original length. By the energization force when energization part 32 returns to the original length, folding guide 4 moves toward nip N3 again, to press the slack LP1 as shown by arrow AR3.
Folding guide 4 finally arrives at the folding position P42. The folding position P42 at where folding guide 4 arrives may be an arbitrary location where the leading end 4a of folding guide 4 is present at the side of the pair of folding rollers 3 with respect to conveying path TR1. The folding position P42 may be a position to push sheet SH into nip N3, or be a position to guide sheet SH close to nip N3.
Referring to
Referring to
Referring to
Referring to
Next, in the state in which folding guide 4 is arranged at the evacuation position P41, post-processing device 51 performs the second folding process. Post-processing device 51 begins to move movable guide 6 toward the guiding position P63 adjacent to nip N2, as shown by arrow AR5. By pushing sheet SH by movable guide 6, post-processing device 51 guides the slack LP2 of sheet SH to nip N2.
Referring to
The size of the slack LP2 before being pushed by movable guide 6 can be adjusted by time t2 as presented above. Hence, the size of the slack LP2 does not become excessively enlarged, as compared to the slack space (the space adjacent to nip N2). Therefore, creases and kinks do not occur on sheet SH, and the slack LP2 can be pushed by sufficient force of movable guide 6 at all times.
Referring to
When the slack LP2 of sheet SH is fed into nip N2, the slack LP2 enlarges, and the tension of sheet SH decreases. The energization force of energization part 34 becomes larger than the tension of sheet SH, and energization part 34 returns to the original length. By the energization force when energization part 34 returns to the original length, movable guide 6 moves toward nip N2 again, to push the slack LP2 further as shown by arrow AR6.
Movable guide 6 finally arrives at the guiding position P63. The guiding position P63 at where movable guide 6 arrives may be an arbitrary location being present at a downstream side of closure position P61 on conveying path TR1. The guiding position P63 at where movable guide 6 arrives may be a position which pushes sheet SH into nip N2, or a position which guides sheet SH near the nip N2.
Referring to
Referring to
Referring to
[The effect of the embodiments]
According to the above embodiments, when sheet SH on which a folding process is not performed is conveyed along with conveying path TR1, or when the leading end of sheet SH before the first folding line is formed is guided to nip N2 of the pair of folding rollers 2, sheet SH is prevented from making contact with the pair of folding rollers 3. Therefore, good performance of feeding paper can be obtained.
When performing the first folding process on sheet SH, movable guide 6 moves to the evacuation position P62. Hence, good performance of feeding paper can be obtained, and the first folding process can be performed smoothly.
When performing the second folding process on sheet SH, movable guide 6 moves to the guiding position P63. Hence, by movable guide 6, the slack LP2 of sheet SH can be guided to nip N2. Herewith, the attitude of the slack LP2 of sheet SH before the second folding process can be stabilized regardless of the basis weight or the like of the sheet SH, so that the variation of the locations of the second folding lines can be easily (inexpensively) prevented. In particular, when movable guide 6 moves to the guiding position P63, the slack LP2 of sheet SH is pushed, to further stabilize the attitude of the slack LP2 of sheet SH before the second folding process.
Further, by providing energization part 34, sheet SH can be prevented from being damaged by movable guide 6 when sheet SH is pushed via the variation of sizes of the slack LP2 of sheet SH.
Further, when performing the first folding process on sheet SH, folding guide 4 moves to the folding position P42. Hence, by folding guide 4, the slack LP1 of sheet SH can be guided to nip N3. Herewith, the attitude of the slack LP1 of sheet SH before the first folding process can be stabilized, regardless of the basis weight or the like of sheet SH, so that the variation of the locations of the first folding lines can be easily (inexpensively) prevented. In particular, when folding guide 4 moves to the folding position P42, the slack LP1 of sheet SH is pushed, to further stabilize the attitude of the slack LP1 of sheet SH before the first folding process.
Further, by providing energization part 32, sheet SH can be prevented from being damaged by folding guide 4 when sheet SH is pushed via the variation of sizes of the slack LP1 of sheet SH.
[Others]
Movable guide 6 may be fixed to closure position P61, and detachable from the main body of post-processing device 51. In this instance, when performing a Z-folding process on a sheet, movable guide 6 may be disengaged.
According to the above-mentioned embodiment, during the second folding process, movable guide 6 has a function as a folding knife which guides a sheet. However, movable guide 6 may not behave as a folding knife (namely, movable guide 6 may not move to the guiding position P63). Further, post-processing device 51 may guide a sheet during the second folding process by a folding knife installed separately from movable guide 6.
Folding guide 4 may be omitted.
As substitute for Z-folding process (three-folding in which areas of 2 planes among the 3 planes are equal), post-processing device 51 may perform three folding process (three-folding in which areas of the 3 planes are equal). Post-processing device 51 may further have a punching function, and a function for a stapling process or the like.
The processes in the above-mentioned embodiments can be performed by software and a hardware circuit. A computer program which executes the processes in the above embodiments can be provided. The program may be provided recorded in recording media of CD-ROMs, flexible disks, hard disks, ROMs, RAMs, memory cards, or the like to users. The program is executed by a computer of a CPU or the like. The program may be downloaded to a device via communication lines like the internet. The processes explained in the above flowcharts and the description are executed by a CPU in line with the program.
Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustrated and example only and is not to be taken by way limitation, the scope of the present invention being interpreted by terms of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-008186 | Jan 2016 | JP | national |
The present U.S. patent application claims a priority under the Paris Convention of Japanese patent application No. 2016-008186 filed on Jan. 19, 2016, the entirety of which is incorporated herein by references.
