SHEET POST-PROCESSING APPARATUS AND SHEET POST-PROCESSING METHOD
In a sheet post-processing apparatus, a sheet guide is arranged above a processing tray that aligns stacked one or plural sheets. The sheet guide is moved by racks to be spaced apart from or brought close to the processing tray. The racks are controlled to be driven on the basis of the number of sheets stacked on the processing tray or the thickness of a stack of the sheets to adjust a space between the processing tray and the sheet guide.
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This application claims the benefit of U.S. Provisional Applications No. 60/944,820, filed Jun. 19, 2007; No. 60/944,824, filed Jun. 19, 2007; and No. 60/944,825, filed Jun. 19, 2007.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to a sheet post-processing apparatus with an improved sheet guide and a sheet post-processing method.
2. Description of the Related Art
A sheet post-processing apparatus is an apparatus that stacks plural sheets on a processing tray and, after aligning these sheets, performs post processing such as staple processing and sort processing of the sheets, and discharges a processed sheet bundle to a stacking tray after the post processing.
The sheet post-processing apparatus includes a sheet guide above the processing tray. However, the sheet guide is fixed in a predetermined position. A space between an upper surface of the processing tray and a ceiling surface of the sheet guide is fixed regardless of the number of sheets stacked on the processing tray. Therefore, for example, if this space is increased to make it possible to stack a bundle of about one-hundred sheets, the sheets may not be able to be stably guided because the space is increased to be too large and some of the sheets may curl when the sheets are about to be stacked on the processing guide. As a result, sheet aligning properties are poor and it is likely that a deficiency occurs in the staple processing and the like. Moreover, when the space is set wide in this way, human fingertips reach the inside of a stapler through the space between the processing tray and the sheet guide, it is likely that an accident occurs.
On the other hand, when the space is reduced to prevent the human fingertips from reaching the inside of the stapler, only a small number of sheets can be stacked on the processing tray. As a result, the number of sheets that can be stapled is limited.
Japanese Patent Disclosure (Kokai) No. 2003-212419; Y. Nakayama et al.; Jul. 30, 2003 discloses a technique for forming a gap between a pressing member 58a and the surface of an aligning tray 41. Since the gap is formed between the pressing member 58a and the surface of the aligning tray 41, when a sheet is conveyed, the pressing member 58a does not prevent the conveyance of the sheet and the sheet can be smoothly conveyed.
BRIEF SUMMARY OF THE INVENTIONThe present invention provides a sheet post-processing apparatus and a sheet post-processing method for not limiting the number of sheets stacked on a processing tray and preventing human fingers from entering a stapler from a space between the processing tray and a sheet guide.
In order to solve the problem, a sheet post-processing apparatus according to an aspect of the present invention is a sheet post-processing apparatus including:
a processing tray that aligns stacked one or plural sheets;
a sheet guide arranged above the processing tray;
a sheet guide driving mechanism that moves the sheet guide to be spaced apart from or brought close to the processing tray; and
a driving control mechanism that controls to drive the sheet guide driving mechanism on the basis of the number of sheets stacked on the processing tray or the thickness of a stack of the sheets and adjusts a space between the processing tray and the sheet guide.
According to an aspect of the present invention, the sheet guide can move from a position close to the processing tray to a position away from the processing tray. Therefore, it is possible to always keep a space between the processing tray and the sheet guide small and prevent human fingers from entering the stapler by mistake to improve safety of the sheet post-processing apparatus. It is also possible to prevent a sheet from curling.
Further, the sheet guide is gradually moved in a direction away from the processing tray to secure a predetermined space between the processing tray and the sheet guide. Therefore, even when a large number of sheets are processed, it is possible to appropriately stack the sheets.
When a small number of sheets are processed, it is unnecessary to move the sheet guide while maintaining a predetermined small space between the processing tray and the sheet guide. Therefore, operability of the sheet post-processing apparatus is improved.
Embodiments of the present invention will be hereinafter explained in detail with reference to the accompanying drawings.
(Overview of an Image forming Apparatus)
An overview of an image forming apparatus (a digital copying machine) and a post-processing apparatus according to an embodiment of the present invention arranged to be connected to a post-stage of the image forming apparatus are explained with reference to
A scanner unit 104, a printer unit 106, and cassettes 152, 153, 154, and 156 and a feeder 155 for copy sheets P are disposed inside the image forming apparatus. The scanner unit 104 scans the original D on the original placing stand 112, makes reflected light of the original D incident thereon, photoelectrically converts the incident reflected light to the read image information of the original D, and outputs a photoelectric signal corresponding to the read image information. The printer unit 106 forms an electrostatic latent image on a circumferential surface of a photoconductive drum 144 using a semiconductor laser 141 according to the image information and the like of the original D read by the scanner unit 104. A developing device 146 supplies a toner to the photoconductive drum 144 and visualizes the electrostatic latent image formed on the photoconductive drum 144 to form a toner image.
The copy sheets P are fed to the photoconductive drum 144 from the cassettes 152, 153, 154, and 156 and the feeder 155 for the copy sheets P. The toner image on the photoconductive drum 144 is copied onto each of the copy sheets P by a transfer charger 148. Thereafter, the toner image on the copy sheet P is fixed by a fixing device 160 and the copy sheet P is discharged from a discharge opening 161. The copy sheet P is equivalent to a sheet M according to the embodiment.
(Overview of the Post-Processing Apparatus)The post-processing apparatus 1 arranged to be connected to the post stage of the digital copying machine includes a standby tray 10 that accumulates several sheets M fed through an entrance roller 2 and an exit roller 4 and puts the sheets M on standby, a processing tray 12 that receives the sheets M dropped from the standby tray 10 and aligns trailing ends of the sheets M for staple processing, a stapler (stapling means) 14 that subjects the trailing ends of the sheets M accumulated in the processing tray 12 and aligned to staple processing (binding processing), a conveying mechanism 50 that conveys the sheets M after being subjected to the staple processing, sort processing, and the like, and a stacking tray 16 (18) on which the conveyed sheets M are stacked.
When the sheets M in the processing tray 12 are subjected to the staple processing, the standby tray 10 puts sheets M, which are conveyed thereto and form the next sheet stack for subsequent post-processing, in a place separate from the processing tray 12 and temporarily keeps the sheets M in a standby state. In this manner, the processing tray 12 secures a time the stapler 14 requires for the staple processing.
The standby tray 10, the processing tray 12, and the stacking tray 16 (18) are provided to incline downward to trailing ends in a feeding direction of the sheets M. A sheet guide 19 is arranged above the processing tray 12 to be spaced apart from the processing tray 12 and guides the sheets M fed to the processing tray 12. The stapler 14 is arranged at the trailing end in the feeding direction of the sheets M of the processing tray 12, stops the sheets M, which are placed on the processing tray 12, on the trailing end side, and performs the staple processing for the sheets M.
(Processing Tray)Four discharge rollers 28a, 28b, 28c, and 28d in total are provided on a leading end side in the conveying direction of the sheet support surface 12a of the processing tray 12. Two of the discharge rollers are provided in the center and the other two are provided on both sides of the sheet support surface 12a, respectively. These discharge rollers are driven to rotate to convey the sheets M to the stacking tray 16 (18).
In the center on the trailing end side of the sheet support surface 12a of the processing tray 12, ejectors 30 are provided to project from the trailing end surface of the processing tray 12. In the center on the leading end side of the sheet support surface 12a of the processing tray 12, bar-like pushing members 32 are arranged. Distal end portions of the pushing members are located between the discharge rollers 28c and 28d in the center. The pushing members 32 are made of, for example, an elastic plate material or a composite member formed by laminating an elastic plate material and a plastic plate material and are integrally attached to the ejectors 30, respectively.
The pushing members 32 are formed of flexible plastic that can be elastically deformed even by a touch of a hand. Frictional members (e.g., rubber) are provided on distal end upper surfaces thereof. The pushing members 32 do not usually project from the processing tray 12 and are in positions further retracted than the discharge rollers 28a, 28b, 28c, and 28d. Therefore, the pushing members 32 do not come into contact with the sheet M. When the pushing members 32 project from the leading end side in the conveying direction of the sheet support surface 12a of the processing tray 12, the frictional members on the leading end upper surfaces come into contact with the lower surface of the sheet M and push up the lower surface of the sheet M.
The ejectors 30 and the pushing members 32 integrally attached to the ejectors 30 are driven by an identical motor to perform a reciprocating action of moving in the direction of the stacking tray 16 and returning from the movement. The ejectors 30 and the pushing members 32 move at the same timing and in the same distance.
A bundle claw belt 40 is arranged between a pair of ejectors 30 and between a pair of pushing members 32. As shown in
In the bundle claw 41 attached to the bundle claw belt 40, as shown in
In the image forming apparatus, as described above, the predetermined setting (e.g., setting of presence or absence of staple processing, a way of the staple processing, the number of copies, and a size of a sheet to be copied) is performed. Therefore, as shown in
In conveying a sheet stacked on the processing tray 12 to the stacking tray 16, the driving control mechanism 60 performs control of the driving motor 38 that drives the ejector 30 and the pushing member 32, the motor 44 that drives the bundle claw belt 40, and the like. For example, when staple processing in the stapler 14 is finished, the driving control mechanism 60 sends a driving signal to the motor 38, moves the ejector 30 and the pushing member 32 in the direction of the stacking tray 16, and, after moving the ejector 30 and the pushing member 32 by a predetermined stroke, returns the same to original positions thereof. The driving control mechanism 60 sends a driving signal to the motor 44 at appropriate timing and moves the bundle claw 41 of the bundle claw belt 40 in the direction of the stacking tray 16. The appropriate timing is timing when a trailing end of the sheet fed by the ejector 30 can be received by the bundle claw 41.
Other EmbodimentsIn the example shown in
In
In the bundle claw 41 shown in
Operations of the post-processing apparatus at the time of a staple mode are explained.
The sheet M is fed from the image forming apparatus to the post-processing apparatus (see an arrow direction in
The processing tray 12 horizontally aligns the sheet M using the horizontal alignment plates 20 and bumps a trailing end of the sheet M against the trailing end stoppers 22 and vertically aligns the sheet M using the paddle 26 and the vertical alignment rollers 24. In this way, the sheet M is vertically and horizontally aligned by the processing tray 12 and guided by the sheet guide 19 and the processing tray 12. The sheet trailing end is guided into the stapler 14. The operation is sequentially applied to the sheets M fed one after another to guide the respective sheets M into the stapler 14.
The sheet guide 19 is initially set at a space with which sheets up to a specified number of sheets, for example, about fifty sheets (about 7 mm thick) can be guided.
When sheets M are increased and exceed the specified number, the sheet guide 19 is moved upward to increase the space between the sheet guide 19 and the processing tray 12.
A stapled sheet bundle is pushed out by the ejector 10 and passed to the bundle claw 41 of the bundle claw belt 40. The bundle claw 41 discharges the sheets M to the stacking tray 16 in cooperation with the discharge rollers 28a, 28b, 28c, and 28d.
(Sort Mode)Operations of the post-processing apparatus at the time of a sort mode are explained.
The sheet M is fed from the image forming apparatus to the post-processing apparatus (see the arrow direction in
In the case of sort, the number of sheets to be discharged (the number of sheets stacked on the processing tray 12) is divided into small numbers of sheets (about one to four sheets).
With the post-processing apparatus, it is possible to set a guide space according to sheet thickness and it is unlikely that human fingers enter the stapler by mistake. If there is information concerning the thickness of sheets, it is possible to control the space by detecting the number of sheets to be conveyed. Moreover, when a smaller number of sheets are processed, it is unnecessary to move the sheet guide 19 up and down while keeping the space set small. Therefore, it is possible to perform processing safely, at high speed, and with controlled noise occurrence.
(Sheet Conveyance)In order to realize the compact structure of the post-processing apparatus, the processing tray 12 and the stacking tray 16 are arranged close to each other. Therefore, the leading end of the sheet M stacked on the processing tray 12 is in contact with the stacking tray 16 (see
When the sheet M is conveyed from the processing tray 12 to the stacking tray 16, first, the ejectors 30 are driven and moved in the direction of the stacking tray 16. Although a position of the trailing end of the sheet M is regulated by the trailing end stoppers 22, the trailing end of the sheet M is caught by the ejectors 30 to move the sheet M in the direction of the stacking tray 16. At this point, the leading end of the sheet M is in contact with the upper surface of the stacking tray 16 or an upper surface of sheets already stacked on the stacking tray 16 and static friction occurs between the sheet and the stacking tray 16. Since a coefficient of static friction is larger than a coefficient of dynamic friction, the leading end of the sheet M in contact with the stacking tray 16 hardly moves. On the other hand, other portions of the sheet M move. As a result, the center of the sheet M starts to bend upward (see
In the post-processing apparatus, the pushing members 32 move in the direction of the stacking tray 16 in synchronization with the ejectors 30. Therefore, simultaneously with the movement of the sheet M by the ejectors 30, a lower surface of the leading end of the sheet M is pushed to relax and reduce a contact force between the lower surface of the leading end of the sheet M and the stacking tray 16 (or the upper surface of the sheets already stacked on the stacking tray 16). As a result, static friction at the leading end of the sheet M is changed to dynamic friction and the entire sheet is conveyed to the stacking tray 16 without curling (see
If the lower surface of the leading end of the sheet M is not pushed by the pushing members 32, since the sheet M is fed to the stacking tray 16 while bending upward, the sheet M is stacked on the stacking tray 16 in a nonaligned state. When stacked plural sheets are conveyed, a leading end of sheets on a lower side hang down (curl to the lower side) unless the leading end is supported by the processing tray 12. When the sheets are conveyed in this state, the sheets on the lower side among the plural sheets are stacked on the stacking tray 16 in a state in which the leading end side thereof is bent inward. With the post-processing apparatus, it is possible to prevent such an unfavorable stacking state.
When the sheets are aligned, the pushing members 32 are located lower than the discharge rollers and do not come into contact with the sheets. After the lower surface of the leading end of the sheets is pushed, since the pushing members 32 return to original positions thereof (positions lower than the discharge rollers), when the sheets are conveyed by the bundle claw 41, the pushing members 32 do not come into contact with the sheets. Therefore, the sheets can be discharged to the stacking tray 16 without a trailing end of the sheet bundle being caught by the pushing members 32.
As described above, with the post-processing apparatus, even if the leading end of the sheet M comes into contact with the stacking tray 16, since the leading end of the sheet M is pushed by the pushing members 32 to relax and reduce a contact force between the stacking tray 16 and the leading end of the sheet, it is possible to prevent the sheet M from bending during conveyance. Therefore, it is possible to appropriately convey even a shin sheet and stacked plural sheets to the stacking tray 16. When the sheet M is pushed by the pushing members 32, conveyance of the sheet M is supported. Therefore, directional properties in conveying the sheet M to the stacking tray 16 are stabilized and stacking alignment properties in the stacking tray 16 are improved.
Further, by integrating the pushing members 32 with the ejectors 30, it is possible to reduce component cost, provide a common driving source for reciprocating movements of the pushing members 32 and the ejectors 30, and reduce sources of occurrence of noise.
Actions of the bundle claw belt 40 in feeding the sheet M to the stacking tray 16 are explained.
The ejectors 30 push the trailing end of the sheet M in the direction of the stacking tray 16 in a predetermined range. The sheet M pushed out a predetermined distance by the ejectors 30 is passed to the bundle claw 41 attached to the bundle claw belt 40. When the number of sheets is small, the trailing end of the sheets comes into contact with the surface 48a on the lower side of the bundle claw 41 (see
Usually, the height of the bundle claw 41 is set large to make it possible to discharge a stapled bundle of one-hundred or more sheets. However, if the bottom surface of the concave portion 46 that regulates the trailing end of the sheet M is flat, in the case of a small number of sheets, the trailing end of the sheets cannot be fixed to a position on the lower surface side of the concave surface of the bundle claw 41 and slides to the upper surface side. The bundle claw belt 40 moves in the direction of the stacking tray 16 on the processing tray 12. However, at a point when the trailing end of the sheets is discharged from the bundle claw belt 40, the bundle claw belt 40 rotates. At this point, if the trailing end of the sheets is located on the lower surface side of the concave surface of the bundle claw 41, where the trailing end of the sheets should be originally located, since the position is a position close to a rotation center of the bundle claw belt 40, speed of discharging the sheets does not change. However, when the trailing end of the sheets moves to the upper surface side of the concave surface of the bundle claw 41, since the trailing end of the sheets is located apart from the rotation center, speed of discharging the sheets increases. As a result, discharge speed fluctuates and the sheets are stacked on the stacking tray 16 in a nonaligned state.
In the post-processing apparatus, when a small number of sheets are discharged from the processing tray 12 to the stacking tray 16, the trailing end of the sheets is located on the lower surface side of the concave surface of the bundle claw 41, where the trailing end of the sheets should be originally located, and does not move to the upper surface side of the concave surface of the bundle claw 41. As a result, fluctuation in discharge speed of the sheets is reduced and it is possible to stably discharge the sheets.
Claims
1. A sheet post-processing apparatus comprising:
- a processing tray that aligns stacked one or plural sheets;
- a sheet guide arranged above the processing tray;
- a sheet guide driving mechanism that moves the sheet guide to be spaced apart from or brought close to the processing tray; and
- a driving control mechanism that controls to drive the sheet guide driving mechanism on the basis of a number of sheets stacked on the processing tray or thickness of a stack of the sheets and adjusts a space between the processing tray and the sheet guide.
2. A sheet post-processing apparatus according to claim 1, wherein the driving control mechanism includes means for controlling to drive the sheet guide driving mechanism to adjust the space every time the number of sheets stacked on the processing tray increases by a predetermined number or predetermined thickness.
3. A sheet post-processing apparatus according to claim 1, wherein the driving control mechanism includes means for controlling the sheet guide driving mechanism to adjust the space every time the number of sheets stacked on the processing tray increases by one.
4. A sheet post-processing apparatus according to claim 1, wherein
- the sheet post-processing apparatus is an apparatus that post-processes a sheet after image processing fed from an image forming apparatus, and
- the driving control mechanism includes means for controlling to drive the sheet guide driving mechanism to adjust the space on the basis of any one of a number of processed sheets fed from the image forming apparatus and thickness of the sheets or both.
5. A sheet post-processing apparatus according to claim 1, wherein
- the sheet post-processing apparatus includes detecting means for detecting a space between a ceiling surface of the sheet guide and a lower surface of the processing tray or an upper surface of sheets stacked on the processing tray, and
- the driving control mechanism includes means for adjusting the space on the basis of a value of the space detected by the detecting means.
6. A sheet post-processing apparatus according to claim 1, wherein the sheet guide driving mechanism includes a rack attached to the sheet guide, a pinion that meshes with the rack, and a motor that drives the pinion.
7. A sheet post-processing apparatus according to claim 1, wherein
- a stapler is arranged on a rear side of the processing tray and a stacking tray is arranged on a front side of the processing tray, and
- the processing tray includes a rear end stopper that positions a rear end of a sheet, a discharge roller that discharges the sheet stacked on the processing tray to a stacking tray, and a horizontal aligning mechanism and a vertical aligning mechanism for the sheet.
8. A sheet post-processing apparatus according to claim 7, wherein the processing tray includes an ejector that pushes out the sheet stacked on the processing tray in a direction of the stacking tray and a pushing member that pushes a lower surface of a trailing end of the sheet fed from the processing tray.
9. A sheet post-processing apparatus comprising:
- means for aligning stacked one or plural sheets;
- means for guiding a sheet arranged above the aligning means;
- sheet guide driving means for moving the sheet guiding means to be spaced apart from or brought close to the aligning means; and
- driving control means for controlling to drive the sheet guide driving means on the basis of a number of sheets stacked on the aligning means or thickness of a stack of the sheets and adjusting a space between the aligning means and the sheet guiding means.
10. A sheet post-processing method comprising:
- stacking one or plural sheets on a processing tray and aligning the sheets;
- moving a sheet guide arranged above the processing tray to be spaced apart from or brought close to the processing tray using a sheet guide driving mechanism; and
- controlling to drive the sheet guide driving mechanism on the basis of a number of sheets stacked on the processing tray or thickness of a stack of the sheets and adjusting a space between the processing tray and the sheet guide driving mechanism.
11. A sheet post-processing method according to claim 10, wherein, when the sheets M in the processing tray are subjected to post-processing, a standby tray 10 puts sheets M, which are conveyed thereto and form a sheet stack for subsequent post-processing, on a standby tray and keeps the sheets M in a standby state, so as to secure a post-processing time.
Type: Application
Filed: Mar 5, 2008
Publication Date: Dec 25, 2008
Applicants: KABUSHIKI KAISHA TOSHIBA (Tokyo), TOSHIBA TEC KABUSHIKI KAISHA (Tokyo)
Inventors: Yasunobu Terao (Izunokuni-shi), Mikio Yamamoto (Izunokuni-shi)
Application Number: 12/042,475
International Classification: B65H 39/00 (20060101);