Patent Application
20050206071
1. Field of the Invention
The present invention relates to a folding device mounted on or operatively connected to a copier, printer or similar image forming apparatus for folding a sheet or recording medium or a sheet stack carrying images thereon or a sheet finisher for folding, sorting, stacking, stapling, center-stapling or otherwise finishing the sheet or the sheet stack, and an image forming system consisting of the sheet finisher and image forming apparatus.
2. Description of the Background Art
A sheet finisher positioned at the downstream side of an image forming apparatus for stapling or otherwise finishing a sheet stack is well known in the art. To meet the increasing demand for multiple functions, a sheet finisher having a center-stapling capability in addition to the conventional edge-stapling capability has recently been proposed. Further, a sheet finisher with a center-folding capability in addition to the center-stapling capability has been proposed to fold a center-stapled sheet stack at the center for thereby producing a pamphlet.
A sheet finisher with the binding capability mentioned above uses, in many cases, one or more pairs of fold rollers to fold a sheet stack. In this type of sheet finisher, a flat fold plate is caused to contact the stapled position of a sheet stack and push it into the nip of each fold roller pair, thereby folding the sheet stack.
When the fold plate is used to push a sheet stack into the nip of each fold roller, it is necessary to locate the sheet stack at a position where it faces the fold roller. Therefore, the fold roller pair located at the first stage is exposed to a sheet conveyance path, so that the sheet stack must be conveyed via the position where the fold roller pair is exposed. At this instant, if the sheet stack is relatively thick, then it is likely that the leading edge of the sheet stack facing the fold roller pair is caused to abut against the rollers or caught by the rollers and bent thereby
In light of the above, it has been customary to use means for preventing a sheet stack from contacting the rollers, e.g., a shutter. The shutter prevents the leading edge of a sheet stack from contacting the rollers until it reaches a preselected position. However, the shutter or similar movable member must be driven by a mechanism arranged in the vicinity of the conveyance path, making the sheet finisher bulky. Moreover, the shutter slides on the surface of a sheet when operated, lowering the quality of an image printed on the sheet.
On the other hand, when a sheet stack is relatively thick, the folding device of the type described is apt to fail to sharply fold the sheet stack, leaving a swell in the sheet stack. To solve this problem, Japanese Patent Laid-Open Publication No. 9-2735, for example, discloses a folding system configured to pass a relatively thick, center-folded sheet stack through the nip of a fold roller pair, reverse the rotation of the fold roller pair to again pass the sheet stack through the above nip, and repeat such a procedure a plurality of times. This system, however, has a drawback that the sheet stack, passed through the nip of the fold roller pair a plurality of times, is smeared around the fold due to sliding contact with the fold roller pair, failing to achieve high quality when implemented as a pamphlet.
To protect a sheet stack from smearing mentioned above, Japanese Patent Laid-Open Publication No. 10-218483, for example, proposes a system that lowers a speed at which a sheet stack is pulled out at the time of reversal of rotation of the fold roller pair, thereby efficiently obviating the swell of the sheet stack. This system, however, cannot fully free a sheet stack from smears although reducing them.
Japanese Patent Laid-Open Publication Nos. 2000-72320 and 2001-146363 each teach a system in which two fold roller pairs are arranged such that the former fold roller pair folds a sheet stack, and then the latter fold roller pair makes the fold of the sheet stack more firm. Although this kind of scheme almost frees a sheet stack form smears, it cannot sharply fold a relatively thick sheet stack and therefore fails to solve the problem of swell. Further, the system is not satisfactory as to productivity and whether or not a desired degree of fold can be formed.
Of course, for a given degree of pressure, the fold of a sheet stack becomes dull as the number of sheets constituting the sheet stack increases. In light of this, Japanese Patent Laid-Open Publication No. 3,254,363, for example, proposes a system including selecting means for selecting either one of a first and a second mode and counting means for counting sheets constituting a single sheets stack. In the first mode, a fold roller pair is rotated only in the forward direction to fold a sheet stack one time while, in the second mode, it is rotated in the forward direction and then in the reverse direction to fold the sheet stack two times. The second mode is selected in accordance with the output of the counting means, thereby sharpening the fold of the sheet stack when more than the sheet stack has more than a preselected number of sheets.
Technologies relating to the present invention are also disclosed in, e.g., Japanese Patent Laid-Open Publication Nos. 9-183568 and 2000-198613.
It is a first object of the present invention to provide a sheet finisher capable of preventing the leading edge portion of a sheet stack from bending, insuring high-quality folding and high-quality center folding and binding without resorting to a shutter or similar special member, and an image forming system including the same.
It is a second object of the present invention to provide a folder and a sheet finisher capable of efficiently obviating the swell of a sheet stack without smearing it and therefore insuring a high-quality bound sheet stack, and an image forming system including the same.
A folding device of the present invention includes a fold plate and a fold roller pair for folding a sheet or a sheet stack conveyed thereto. A controller causes the fold roller pair to move back and forth while nipping the folded portion of the sheet or that of the sheet stack at its nip for thereby continuously exerting pressure on the folded portion. The fold roller pair is rotated in opposite directions for thereby sharpening the fold of the sheet or that of the sheet stack.
A sheet finisher including the folding device and an image forming system consisting of the sheet finisher and an image forming apparatus are also disclosed.
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken with the accompanying drawings in which:
Preferred embodiments of the sheet finisher and image forming system in accordance with the present invention will be described hereinafter.
Referring to
The image forming apparatus PR includes at least an image processor, an optical writing unit, a developing unit, an image transferring unit, and a fixing unit although not shown specifically. The image processor converts an image signal input thereto to image data that can be printed out. The optical writing unit optically scans the surface of a photoconductive element in accordance with the image data output from the image processor, thereby forming a latent image. The developing unit develops the latent image with toner to thereby produce a corresponding toner image. The image transferring unit transfers the toner image to a sheet. The fixing unit fixes the toner image on the sheet. While the image forming apparatus PR is assumed to execute an electrophotographic process, it may alternatively be of the type executing any other conventional image forming process, e.g., an ink-jet or a thermal transfer image forming process. In the illustrative embodiment, the image processor, optical writing unit, developing unit, image transferring unit and fixing unit constitute image forming means in combination.
Sheets sequentially brought to the staple tray F via the paths A and D are positioned one by one, stapled or otherwise processed, and then steered by a guide plate 54 and a movable guide 55 to either one of the path C and another processing tray G. The processing tray G folds or otherwise processes the sheets and, in this sense, will sometimes be referred to as a fold tray hereinafter. The sheets folded by the fold tray G are guided to a lower tray 203 via a path H. The path D includes a path selector 17 constantly biased to a position shown in
On the path A merging into the paths B, C and D, there are sequentially arranged an inlet sensor 301 responsive to a sheet coming into the finisher PD, an inlet roller pair 1, the punch unit 100, a waste hopper 101, roller pair 2, and the path selectors 15 and 16. Springs, not shown, constantly bias the path selectors 15 and 16 to the positions shown in
More specifically, to guide a sheet to the path B, the path selector 15 is held in the position shown in
In the illustrative embodiment, the finisher PD is capable of selectively effecting punching (punch unit 100), jogging and edge stapling (jogger fence 53 and edge stapler S1), sorting (shift tray 202) or folding (fold plate 74 and fold rollers 81 and 82), as desired.
A shift tray outlet section I is located at the most downstream position of the sheet finisher PD and includes a shift outlet roller pair 6, a return roller 13, a sheet surface sensor 330, and the shift tray 202. The shift tray outlet section I additionally includes a shifting mechanism J shown in
As shown in
As shown in
More specifically, in the illustrative embodiment, the sensors 330a and 330b each turn on when interrupted by the interrupter 30b of the lever 30. Therefore, when the shift tray 202 is lifted with the contact end 30a of the lever 30 moving upward, the sensor 330a turns off. As the shift tray 202 is further lifted, the sensor 330b turns off. When the outputs of the sensors 330a and 330b indicate that sheets are stacked on the shift tray 202 to a preselected height, the tray elevation motor 168 is driven to lower the shift tray 202 by a preselected amount. The top of the sheet stack on the shift tray 202 is therefore maintained at a substantially constant height.
The shift tray elevating mechanism K will be described in detail with reference to
The drive unit L includes a worm gear 25 in addition to the tray elevation motor 168, which is a reversible drive source. Torque output from the tray elevation motor 168 is transmitted to the last gear of a gear train mounted on the drive shaft 21 to thereby move the shift tray 202 upward or downward The worm gear 25 included in the driveline allows the shift tray 202 to be held at a preselected position and therefore prevents it from dropping by accident.
An interrupter 24a is formed integrally with the side plate 24 of the shift tray 202. A full sensor 334 responsive to the full condition of the shift tray 202 and a lower limit sensor 335 responsive to the lower limit position of the shift tray 202 are positioned below the interrupter 24a. The full sensor 334 and lower limit sensor 335, which are implemented by photosensors, each turn off when interrupted by the interrupter 24a. In FIG. 3, the shift outlet roller 6 is not shown.
As shown in
Guide channels 32c are formed in the front surface of the end fence 32. The rear edge portions of the shift tray 202 are movably received in the guide channels 32c. The shift tray 202 is therefore movable up and down and movable back and forth in the direction perpendicular to the direction of sheet discharged, as needed. The end fence 32 guides the trailing edges of sheets stacked on the shift tray 202 for thereby aligning them.
As shown in
As shown in
More specifically, torque output from the discharge motor 157 is transferred to the discharge belt 52 via a timing belt and the timing pulley 62. The timing pulley (drive pulley) 62 and discharge rollers 56 are mounted on the same shaft, i.e., the discharge shaft 65. An arrangement maybe made such that when the relation in speed between the discharge rollers 56 and the discharge belt 52 should be varied, the discharge rollers 56 are freely rotatable on the discharge shaft 65 and driven by part of the output torque of the discharge motor 157. This kind of scheme allows a desired reduction ratio to be set up.
The surface of the discharge roller 56 is formed of rubber or similar high-friction material. The discharge roller 56 nips a sheet stack between it and a press roller or driven roller 57 due to the weight of the driven roller 57 or a bias, thereby conveying the sheet stack.
A processing mechanism will be described hereinafter. As shown in
As shown in.
As shown in
As shown in
There are also shown in
Reference will be made to
As shown in
The movable guide 55 is angularly movably mounted on the shaft of the discharge roller 56. A link arm 60 is connected to one end of the movable guide 55 remote from the guide plate 54 at a joint 60a. A pin studded on the front side wall 64a,
When the leading edge of a sheet stack steered by the guide plate 54 contacts the guide surface 55a of the movable guide 55, the guide surface 55a causes the leading edge to make a hairpin turn with a small diameter R. When the cam 61 is in the home position, the movable guide 55 abuts against a plate, not shown, and biased by the spring 59 in the counterclockwise direction.
In the condition shown in
In the condition shown in
Although the path selectors 15 and 16 shown in
While in the illustrative embodiment the guide plate 54 and movable guide 55 share a single drive motor, each of them may be driven by a respective drive motor, so that the timing of movement and stop position can be controlled in accordance with the sheet size and the number of sheets stapled together.
The fold tray G will be described specifically with reference to
A fold plate motor 166 causes the fold plate cam 75 to rotate in a direction indicated by an arrow in
While the illustrative embodiment is assumed to fold a sheet stack at the center, it is capable of folding even a single sheet at the center. In such a case, because a single sheet does not have to be stapled at the center, it is fed to the fold tray G as soon as it is driven out, folded by the fold plate 74 and fold roller pair 81, and then delivered to the lower tray 203,
The angle of the staple tray F should preferably be as small as possible in order to reduce the projection area in the vertical direction and therefore the area to be occupied by the sheet finisher PD. However, in the illustrative embodiment, the fold plate 74, link arm 76, fold plate cam 75 and fold plate motor 166 constituting the folding mechanism of
To fold a sheet stack at the center, the center of the sheet stack should be coincident with a folding position assigned to the fold plate 74, as will be described specifically later. For this purpose, in the illustrative embodiment, a movable rear fence 73 is included in the lower guide plate 91 such that the trailing edge of a folded sheet stack (leading edge when the sheet stack is to be conveyed) rests on the fence 73. The movable rear fence 73 is movable upward or downward to bring the center of the sheet stack resting thereon to the folding position.
As shown in
As shown in
The unit U having the above configuration can be pulled out in the event of a jam and allows a jamming sheet to be easily removed. More specifically, when a jam occurs at the fold tray G side, the operator should only pull out the unit U halfway and can rapidly deal with the jam while watching the guide plates 91 and 92 opened away from each other. After the jam processing, when the operator pushes the unit U into the finisher PD, the guide plates 91 and 92 are automatically closed by the edges of the opening 67 and locked by the magnet. This obviates an occurrence that the operator fails to close the guide plates 91 and 92 and makes the next step impracticable.
While the guide rails 66 are positioned at the fold tray G side of the opening 67, they may, of course, be located at any other position, e.g., a position above the guide plates 91 and 92.
In the illustrative embodiment, the staple tray F is inclined by a large angle in relation to the fold tray G and folding mechanism, i.e., positioned obliquely at as small an angle as possible relative to the fold tray G, as stated earlier. In this arrangement, the fold tray G is positioned below the staple tray F, so that the space above the staple tray F is questionable in the aspect of efficient use of space. In light of this, in the illustrative embodiment, the path D and prestacking portion E are positioned in parallel to the staple tray F while a waste receiver 101a included in the waste unit 101 is held in an inclined position in the space available in the upper right portion, as seen in
In the above configuration, if the sheet size is large, then a sheet stored in the prestacking portion E waits for the next sheet with its trailing edge in the direction of sheet conveyance protruding from the portion E. At this instant, because the sheet prestacking portion E is positioned in the upper right portion of the finisher PD, a sufficient space is available below the portion E and prevents the sheet from jamming the path.
Further, the folding mechanism of the fold tray G is located between the edge stapler S1 and the center staplers S2, so that a sufficient space is available below the fold plate 74 even when the sheet size is large. Therefore, a sufficient space is guaranteed below the leading edge of a sheet despite that the sheet is conveyed vertically along the guide plates 91 and 92.
Reference will be made to
The CPU 360 controls, based on the above various inputs, the tray motor 168 assigned to the shift tray 202, the guide plate motor 167 assigned to the guide plate, the shift motor 169 assigned to the shift tray 202, a knock roller motor, not shown, assigned to the knock roller 12, various solenoids including the knock solenoid (SOL) 170, motors for driving the conveyor rollers, outlet motors for driving the outlet rollers, the discharge motor 157 assigned to the belt 52, the stapler motor 159 assigned to the edge stapler S1, the jogger motor 158 assigned to the jogger fences 53, the steer motor 161 assigned to the guide plate 54 and movable guide 55, a motor, not shown, assigned to rollers for conveying a sheet stack, a rear fence motor assigned to the movable rear fence 73, and a fold roller motor, not shown, assigned to the fold roller 81. The pulse signals of a staple conveyance motor, not shown, assigned to the staple discharge rollers are input to the CPU 360 and counted thereby. The CPU 360 controls the knock SOL 170 and jogger motor 158 in accordance with the number of pulse signals counted. The fold roller motor is implemented by a stepping motor and controlled by the CPU 360 either directly via a motor driver or indirectly via the I/O 370 and motor driver.
Further, the CPU 360 causes the punch unit 100 to operate by controlling a clutch or a motor. The CPU 360 controls the finisher PD in accordance with a program stored in a ROM (Read Only Memory), not shown, by using a RAM (Random Access Memory) as a work area.
Specific operations to be executed by the CPU 360 in various modes available with the illustrative embodiment will be described hereinafter.
First, in a non-staple mode A, a sheet is conveyed via the paths A and B to the upper tray 201 without being stapled. To implement this mode, the path selector 15 is moved clockwise, as viewed in
As shown, before a sheet driven out of the image forming apparatus PR enters the finisher PD, CPU 360 causes the inlet roller pair 1 and conveyor roller pair 2 on the path A to start rotating (step S101). The CPU 360 then checks the ON/OFF state of the inlet sensor 301 (steps S102 and S103) and the ON/OFF state of the upper outlet sensor 302 (steps S104 and S105) for thereby confirming the passage of sheets. When a preselected period of time elapses since the passage of the last sheet (YES, step S106), the CPU 360 causes the above rollers to stop rotating (step S107). In this manner, all the sheets handed over from the image forming apparatus PR to the finisher PD are sequentially stacked on the upper tray 201 without being stapled. If desired, the punch unit 100, which intervenes between the inlet roller pair 1 and conveyor roller pair 2, may punch the consecutive sheets.
In a non-staple mode B, the sheets are routed through the paths A and C to the shift tray 202. In this mode, the path selectors 15 and 16 are respectively moved counterclockwise and clockwise, unblocking the path C. The non-staple mode B will be described with reference to
As shown, before a sheet driven out of the image forming apparatus PR enters the finisher PD, CPU 360 causes the inlet roller pair 1 and conveyor roller pair 2 on the path A and the conveyor roller pair 5 and shift outlet roller pair 6 on the path C to start rotating (step S201). The CPU 360 then energizes the solenoids assigned to the path selectors 15 and 16 (step S202) to thereby move the path selectors 15 and 16 counterclockwise and clockwise, respectively. Subsequently, the CPU 360 checks the ON/OFF state of the inlet sensor 301 (steps S203 and S204) and the ON/OFF state of the shift outlet sensor 303 (steps S205 and S206) to thereby confirm the passage of the sheets.
On the elapse of a preselected period of time since the passage of the last sheet (YES, step S207), the CPU 360 causes the various rollers mentioned above to stop rotating (S208) and deenergizes the solenoids (steps S209). In this manner, all the sheets entered the finisher PD are sequentially stacked on the shift tray 202 without being stapled. Again, the punch unit 100 intervening between the inlet roller pair 1 and conveyor roller pair 2 may punch the consecutive sheets, if desired.
In a sort/stack mode, the sheets are also sequentially delivered from the path A to the shift tray 202 via the path C. A difference is that the shift tray 202 is shifted perpendicularly to the direction of sheet discharge copy by copy in order to sort the sheets. The path selectors 15 and 16 are respectively rotated counterclockwise and clockwise as in the non-staple mode B, thereby unblocking the path C. The sort/stack mode will be described with reference to
As shown, before a sheet driven out of the image forming apparatus PR enters the finisher PD, CPU 360 causes the inlet roller pair 1 and conveyor roller pair 2 on the path A and the conveyor roller pair 5 and shift outlet roller pair 6 on the path C to start rotating (step S301). The CPU 360 then energizes the solenoids assigned to the path selectors 15 and 16 (step S302) to thereby move the path selectors 15 and 16 counterclockwise and clockwise, respectively. Subsequently, the CPU 360 checks the ON/OFF state of the inlet sensor 301 (steps S303 and S304) and the ON/OFF state of the shift outlet sensor 303 (step S305)
If the sheet passed the shift outlet sensor 303 is the first sheet of a copy (YES, step S306), then the CPU 360 turns on the shift motor 169 (step S307) to thereby move the shift tray 202 perpendicularly to the direction of sheet conveyance until the shift sensor 336 senses the tray 202 (steps S308 and S309). When the sheet moves away from the shift outlet sensor 303 (YES, step S310), the CPU 360 determines whether or not the sheet is the last sheet (step S311). If the answer of the step S311 is No, meaning that the sheet is not the last sheet of a copy, and if the copy is not a single sheet, then the procedure returns to the step S303. If the copy is a single sheet, then the CPU 360 executes a step S312.
If the answer of the step S306 is NO, meaning that the sheet passed the shift outlet sensor 303 is not the first sheet of a copy, then the CPU 360 discharges the sheet(step S310) because the shift tray 202 has already been shifted. The CPU 360 then determines whether or not the discharged sheet is the last sheet (step S311). If the answer of the step. S311 is NO, then the CPU 360 repeats the step S303 and successive steps with the next sheet. If the answer of the step S311 is YES, then the CPU 360 causes, on the elapse of a preselected period of time, the inlet roller pair 1, conveyor roller pairs 2 and 5 and shift outlet roller pair 6 to stop rotating (step S312) and deenergizes the solenoids assigned to the path selectors 15 and 16 (step S313). In this manner, all the sheets sequentially entered the finisher PD are sorted and stacked on the shift tray 202 without being stapled. In this mode, too, the punch unit 100 may punch the consecutive sheets, if desired.
In a staple mode, the sheets are conveyed from the path A to the staple tray F via the path D, positioned and stapled on the staple tray F, and then discharged t the shift tray 202 via the path C. In this mode, the path selectors 15 and 16 both are rotated counterclockwise to unblock the route extending from the path A to the path D. The staple mode will be described with reference to
As shown, before a sheet driven out of the image forming apparatus PR enters the finisher PD, CPU 360 causes the inlet roller pair 1 and conveyor roller pair 2 on the path A and the conveyor roller pairs 7, 9 and 10 and staple outlet roller 11 on the path D and knock roller 12 to start rotating (step S401). The CPU 360 then energizes the solenoid assigned to the path selector 15 (step S402) to thereby cause the path selector 15 to rotate counterclockwise.
After the stapler HP sensor 312 has sensed the edge stapler S1 at the home position, the CPU 360 drives the stapler motor 159 to move the edge stapler Si to a preselected stapling position (step S403). Also, after the belt HP sensor 311 has sensed the belt 52 at the home position, the CPU 360 drives the discharge motor 157 to bring the belt 52 to a stand-by position (step S404). Further, after the jogger fence motor HP sensor has sensed the jogger fences 53 at the home position, the CPU 360 moves the jogger fences 53 to a stand-by position (step S405). In addition, the CPU 360 causes the guide plate 54 and movable guide 55 to move to their home positions (step S406).
If the inlet sensor 301 has turned on (YES, step S407) and then turned off (YES, step S408), if the staple discharge sensor 305 has turned on (YES, step S409) and if the shift outlet sensor 303 has tuned on (YES, step S410), then the CPU 360 determines that a sheet is present on the staple tray F. In this case, the CPU 360 energizes the knock solenoid 170 for a preselected period of time to cause the knock roller 12 to contact the sheet and force it against the rear fences 51, thereby positioning the rear edge of the sheet (step S411). Subsequently, the CPU 360 drives the jogger motor 158 to move each jogger fence 53 inward by a preselected distance for thereby positioning the sheet in the direction of width perpendicular to the direction of sheet conveyance and then returns the jogger fence 53 to the stand-by position (step S412). The CPU 360 repeats the step S407 and successive steps with every sheet. When the last sheet of a copy arrives at the staple tray F (YES, step S413), the CPU 360 moves the jogger fences 53 inward to a position where they prevent the edges of the sheets from being dislocated (step S414). In this condition, the CPU 360 turns on the stapler S1 and causes it to staple the edge of the sheet stack (step S415).
On the other hand, the CPU 360 lowers the shift tray 202 by a preselected amount (step S416) in order to produce a space for receiving the stapled sheet stack. The CPU 360 then drives the shift discharge roller pair 6 via the shift discharge motor (step S417) and drives the belt 52 by a preselected amount via the discharge motor 157 (step S418), so that the stapled sheet stack is raised toward the path C. As a result, the stapled sheet stack is driven out to the shift tray 202 via the shift outlet roller pair 6. After the shift outlet sensor 303 has turned on (step S419) and then turned off (step S420), meaning that the sheet stack has moved away from the sensor 303, the CPU 360 moves the belt 52 and jogger fences 53 to their stand-by positions (steps S421 and S422), causes the shift outlet roller pair 6 to stop rotating on the elapse of a preselected period of time (step S423), and raises the shift tray 202 to a sheet receiving position (step S424). The rise of the shift tray 202 is controlled in accordance with the output of the sheet surface sensor 330 responsive to the top of the sheet stack positioned on the shift tray 202.
After the last copy or set of sheets has been driven out to the shift tray 202, the CPU 360 returns the edge stapler S1, belt 52 and jogger fences 53 to their home positions (steps S426, S427 and S428) and causes the inlet roller pair 1, conveyor roller pairs 2, 7, 9 and 10, staple discharge roller pair 11 and knock roller 12 to stop rotating (step S429). Further, the CPU 360 deenergizes the solenoid assigned to the path selector 15 (step S430. Consequently, all the structural parts are returned to their initial positions. In this case, too, the punch unit 100 may punch the consecutive sheets before stapling.
The operation of the staple tray F in the staple mode will be described more specifically hereinafter. As shown in
The staple discharge sensor 305 senses the trailing edge of the sheet and sends its output to the CPU 360. In response, the CPU 360 starts counting drive pulses input to the staple motor, not shown, driving the staple discharge roller pair 11. On counting a preselected number of pulses, the CPU 360 energizes the knock solenoid 170 (step S412). The knock solenoid 170 causes the knock roller 12 to contact the sheet and force it downward when energized, so that the sheet is positioned by the rear fences 51. Every time a sheet to be stacked on the staple tray F1 passes the inlet sensor 301 or the staple discharge sensor 305, the output of the sensor 301 or 305 is sent to the CPU 360, causing the CPU 360 to count the sheet.
On the elapse of a preselected period of time since the knock solenoid 170 has been turned off, the CPU 360 causes the jogger motor 158 to move each jogger fence 53 further inward by 2.6 mm and then stop it, thereby positioning the sheet in the direction of width. Subsequently, the CPU 360 moves the jogger fence 53 outward by 7.6 mm to the stand-by position and then waits for the next sheet (step S412). The CPU 360 repeats such a procedure up to the last page (step S413). The CPU 360 again causes the jogger fences 53 to move inward by 7 mm and then stop, thereby causing the jogger fences 53 to retain the opposite edges of the sheet stack to be stapled. Subsequently, on the elapse of a preselected period of time, the CPU 360 drives the edge stapler S1 via the staple motor for thereby stapling the sheet stack (step S415). If two or more stapling positions are designated, then the CPU 360 moves, after stapling at one position, the edge stapler S1 to another designated position along the rear edge of the sheet stack via the stapler motor 159. At this position, the edge stapler S1 again staples the sheet stack. This is repeated when three or more stapling positions are designated.
After the stapling operation, the CPU 360 drives the belt 52 via the discharge motor 157 (step S418). At the same time, the CPU 360 drives the outlet motor to cause the shift outlet roller pair 6 to start rotating in order to receive the stapled sheet stack lifted by the hook 52a (step S417). At this instant, the CPU 360 controls the jogger fences 53 in a different manner in accordance with the sheet size and the number of sheets stapled together. For example, when the number of sheets stapled together or the sheet size is smaller than a preselected value, then the CPU 360 causes the jogger fences 53 to constantly retain the opposite edges of the sheet stack until the hook 52a fully lifts the rear edge of the sheet stack. When a preselected number of pulses are output since the turn-on of the sheet sensor 310 or the belt HP sensor 311, the CPU 360 causes the jogger fences 53 to retract by 2 mm and release the sheet stack. The preselected number of pulses corresponds to an interval between the time when the hook 52a contacts the trailing edge of the sheet stack and the time when it moves away from the upper ends of the jogger fences 53.
On the other hand, when the number of sheets stapled together or the sheet size is larger than the preselected value, the CPU 360 causes the jogger fences 53 to retract by 2 mm beforehand. In any case, as soon as the stapled sheet stack moves away from the jogger fences 53, the CPU 360 moves the jogger fences 53 further outward by 5 mm to the stand-by positions (step S422) for thereby preparing it for the next sheet. If desired, the restraint to act on the sheet stack may be controlled on the basis of the distance of each jogger fence from the sheet stack.
In a center staple and bind mode, the sheets are sequentially conveyed from the path A to the staple tray F via the path D, positioned and stapled at the center on the tray F, folded on the fold tray G, and then driven out to the lower tray 203 via the path E. In this mode, the path selectors 15 and 16 both are rotated counterclockwise to unblock the route extending from the path A to the path D. Also, the guide plate 54 and movable guide plate 55 are closed, as shown in
As shown, before a sheet driven out of the image forming apparatus PR enters the finisher PD, CPU 360 causes the inlet roller pair 1 and conveyor roller pair 2 on the path A and the conveyor roller pairs 7, 9 and 10 and staple outlet roller 11 on the path D and knock roller 12 to start rotating (step S401) The CPU 360 then energizes the solenoid assigned to the path selector 15 (step 5402) to thereby cause the path selector 15 to rotate counterclockwise.
Subsequently, after the belt HP sensor 311 has sensed the belt 52 at the home position, the CPU 360 drives to the discharge motor 157 to move the belt 52 to the stand-by position (step S503). Also, after the jogger fence HP sensor has sensed each jogger fence 53 at the home position, the CPU 360 moves the jogger fence 53 to the stand-by position (step 5504) Further, the CPU 360 moves the guide plate 54 and movable guide 55 to their home positions (steps S505).
If the inlet sensor 301 has turned on (YES, step S506) and then turned off (YES, step S507), if the staple discharge sensor 305 has turned on (YES, step S508) and if the shift outlet sensor 303 has tuned on (YES, step 5509), then the CPU 360 determines that a sheet is present on the staple tray F. In this case, the CPU 360 energizes the knock solenoid 170 for the preselected period of time to cause the knock roller 12 to contact the sheet and force it against the rear fences 51, thereby positioning the 6 trailing edge of the sheet (step S510). Subsequently, the CPU 360 drives the jogger motor 158 to move each jogger fence 53 inward by the preselected distance for thereby positioning the sheet in the direction of width perpendicular to the direction of sheet conveyance and then returns the jogger fence 53 to the stand-by position (step S511). The CPU 360 repeats the step S407 and successive steps with every sheet. When the last sheet of a copy arrives at the staple tray F (YES, step S512), the CPU 360 moves the jogger fences 53 inward to the position where they prevent the edges of the sheets from being dislocated (step S513).
After the step S513, the CPU 360 turns on the discharge motor 157 to thereby move the belt 52 by a preselected amount (step S514), so that the belt 52 lifts the sheet stack to a stapling position assigned to the center staplers S2. Subsequently, the CPU 360 turns on the center staplers S2 at the intermediate portion of the sheet stack for thereby stapling the sheet stack at the center (step S515). The CPU 360 then moves the guides 54 and 55 by a preselected amount each in order to form a path directed toward the fold tray G (step S516) and causes the upper and lower roller pairs 71 and 72 of the fold tray G to start rotating (step S517). As soon as the movable rear fence 73 of the fold tray G is sensed at the home position, the CPU 360 moves the fence 73 to a stand-by position (step S518). The fold tray G is now ready to receive the stapled sheet stack.
After the step S518, the CPU 360 further moves the belt 52 by a preselected amount (step S519) and causes the discharge roller 56 and press roller 57 to nip the sheet stack and convey it to the fold tray G. After the leading edge of the stapled sheet stack has arrived at the stack arrival sensor 321 (step S520), the CPU 360 causes the fold roller pair 81 to rotate in the reverse direction (step 5521), so that the sheet stack can be conveyed downward without being folded at a portion Q (see
In the above condition, the CPU 360 determines whether or not the trailing edge of the folded sheet stack has moved away from the lower outlet sensor 324 (steps S532 and S533). If the answer of the step S533 is YES, then the CPU 360 causes the fold roller pairs 81 and 82 and lower outlet roller pair 83 to further rotate for a preselected period of time and then stop (step S534) and then causes the belt 52 and jogger fences 53 to return to the stand-by positions (steps S535 and S536). Subsequently, the CPU 360 determines whether or not the above sheet stack is the last copy of a single job to perform (step S537) If the answer of the step S537 is NO, then the procedure returns to the step S506. If the answer of the step S537 is YES, then the CPU 360 returns the belt 52 and jogger fences 53 to the home positions (steps S538 and 5539). At the same time, the CPU 360 causes the inlet roller pair 1, roller pairs 2, 7, 9 and 10, staple discharge roller pair 11 and knock roller 12 to stop rotating (step S540) and turns off the solenoid assigned to the path selector 15 (step S541). As a result, all the structural parts are returned to their initial positions.
The stapling and folding operations to be performed in the center fold mode will be described in more detail hereinafter. A sheet is steered by the path selectors 15 and 16 to the path D and then conveyed by the roller pairs 7, 9 and 10 and staple discharge roller 11 to the staple tray F. The staple tray F operates in exactly the same manner as in the staple mode stated earlier before positioning and stapling (see
Subsequently, as shown in
As shown in
As shown in
As shown in
As stated above, in the illustrative embodiment, the direction of rotation of the fold roller is switched in accordance with whether a sheet should be folded by the fold roller or whether it should be guide to a preselected position on a path before folding. It is therefore possible to guide the leading edge of a sheet stack in the direction of conveyance when the sheet stack should be introduced into the path. The illustrative embodiment therefore protects the leading edge portion of a sheet stack from bending without resorting to a shutter or similar special member, thereby insuring desirable folding and therefore desirable center stapling and folding.
More specifically, in the illustrative embodiment, the prestacking portion E is positioned on the path D, which extends to the staple tray F, and allows two or more sheets to be conveyed to the staple tray F together. Therefore, the entry or the first sheet of the next set of sheets in the stapling section can be delayed without regard to the edge/center staple mode. It follows that high productivity is achievable the positioning and stapling time being intentionally reduced.
The comparatively short path C allows sheets to be driven out to the same tray (shift tray 202) without regard to stapling/non-stapling. Sheets can therefore be driven out in two different modes at the minimum cost.
Further, either one of the edge stapler S1 and center staplers S2, which are independent of each other, suitable for stapling is always positioned in the vicinity of the position assigned to the jogger fence 53. This successfully reduces the overall positioning and stapling time and thereby guarantees high productivity. In addition, the belt 52 and hook 52a can selectively move a sheet stack to the upstream side or the downstream side in the direction of conveyance, implementing the delicate adjustment of the stapling position, as desired.
Moreover, the stack moving means plays the role of an edge guide for guiding the lower edge of a sheet stack at the same time, simplifying the construction and reducing cost. In addition, the positioning position is variable in accordance with the sheet size and the number of sheets to be stapled together, so that accurate positioning and productivity are enhanced.
An alternative embodiment of the sheet finisher and image forming apparatus in accordance with the present invention will be described hereinafter. The illustrative embodiment is essentially similar to the previous embodiment except for the following.
In the center staple and fold mode, the illustrative embodiment also executes the procedure shown in
In the steps S527 and S528, the illustrative embodiment makes the fold of a sheet stack more sharp, or more firm, with a sequence of steps shown in
In the step S527-2, after the fold roller pair 82 has nipped the leading edge of the sheet stack, the CPU 360 causes both of the fold roller pairs 81 and 82 to stop rotating with the roller pair 81 nipping the intermediate portion of the sheet stack, thereby sharpening the fold of the sheet stack (see
As shown in
While the periods of time T1 through T4 each are variable in accordance with the sheet size and the number of sheets, the larger the sheet size and the larger the number of sheets, the longer the period of time necessary for the next sheet stack to enter the folding section. Therefore, the period of time necessary for the next sheet stack to enter the folding section is used as a pressing time for thereby efficiency pressing the folded sheet stack without lowering productivity, i.e., without wasting time. The fold of the sheet stack is therefore sharpened and efficiently freed from a swell.
As stated above, within the preselected period of time for pressing the fold of the sheet stack, the procedure of
It is to be noted that the duration of the reciprocating motion described with reference to
After the step S527-4, when the trailing edge of the sheet stack moves away from the pass sensor 323 (YES, step S528), the CPU 360 presses the lower rollers 72 against each other (step S529) and moves the fold plate 74 and guide plates 54 and 55 to their home positions (steps S530 and S531).
In the above condition, the lower outlet sensor 324 monitors the passage of the sheet stack (steps 5532 and S533). When the trailing edge of the sheet stack moves away from the lower outlet sensor 324 (YES, step S533), the CPU 360 causes the fold roller pairs 81 and 82 and lower outlet roller pair 83 to further rotate over a preselected period of time and then stop rotating (step 3534). Subsequently, the CPU 360 returns the belt 52 and jogger fence 53 to their stand-by positions (steps S535 and S536) and then determines whether or not the sheet stack is the last stack to be dealt with by the job (step S537). If the answer of the step S537 is NO, then the procedure returns to the step S506. If the answer of the step S537 is YES, then the CPU 360 moves the belt 52 and jogger fence 53 to the home positions (steps S538 and S539), stops rotating the inlet roller pair 1, roller pairs 2, 7, 9 and 10, staple outlet roller pair 11, and knock roller 12 (step S540) Subsequently, the CPU 360 turns off the solenoid assigned to the path selector 15 (step 5541), thereby restoring the initial condition.
The stapling and folding operations which the illustrative embodiment performs in the center staple and fold mode will be described more specifically hereinafter. As shown in
As soon as the leading edge of the sheet stack enters the nip of the fold roller pair 82, the fold roller pairs 81 and 82 stop rotating and again start rotating on the elapse of a preselected period of time (corresponding to the procedure of
Again, within the preselected period of time, the fold roller pair 82 may be caused to repeatedly rotate in opposite directions (solid arrow and phantom arrow,
As shown in
As stated above, the illustrative embodiment has various unprecedented advantages, as enumerated below.
(1) A fold roller pair stops the fold of a sheet stack at its nip over a preselected period of time to thereby sharpen the fold. This frees part of the sheet stack around the fold from smears ascribable to sliding contact with the roller pair, while efficiently obviating the swell of the sheets stack. This is contrastive to the conventional system in which a sheet stack Is moved back and forth via the nip of a roller pair a plurality of times so as to have its fold intermittently pressed.
(2) Because the sheet stack is pressed while in a stop, it should only be nipped by the fold roller over a preselected period of time. Simple control therefore suffices for sharpening the fold.
(3) The fold of the sheet stack is pressed within the nip width of the fold roller pair parallel to the direction of conveyance. Therefore, simple control suffices for sharpening the fold if the fold roller pair is rotated in opposite directions within the above range.
(3) The duration of pressure to act on the fold of the Sheet stack is variable in accordance with the sheet size and the number of sheets constituting a stack. Therefore, by using the fact that the period of time necessary for the next sheet stack to reach a folding section increases with an increase in sheet size or the number of sheets, such a period of time can be used to press the fold. This makes it needless to add a wasteful period of time that would lower the productivity of an image forming apparatus.
Another alternative embodiment of the sheet finisher and image forming apparatus in accordance with the present invention will be described hereinafter. This embodiment is also directed mainly toward the second object and similar to the second embodiment except for the configuration and operation of the fold plate 74 and those of the fold roller pair 81. The following description will concentrate on differences between the second and third embodiments.
In
The plates 511a and 511b are angularly movably supported by fulcrums 510a and 510b, respectively, which are positioned on the front and rear side walls of the fold tray G. The swing arms 520a and 520b are respectively swingably supported by the plates 511a and 511b via bearings 515a and 515b at one end thereof. The second springs 512a and 512b respectively exert on the plates 511a and 511b pressure necessary for conveying a sheet stack at the upstream end in the direction in which the fold rollers 81a and 81b convey the sheet stack. The plates 511a and 511b, fulcrums 510a and 510b, swing arms 520a and 520b and first and second springs 512, 512a and 512b each are provided in pair on the inner surfaces of the front and rear side walls of the fold tray G, although not shown specifically. The fold rollers 81a and 81b are mounted on respective shafts expending perpendicularly to the direction of conveyance.
At the upstream side in the direction of sheet conveyance, the first springs 512a and 512b constantly bias the plates 511a and 511b, respectively, such that their free ends tend to move toward each other. The fold rollers 81a and 81b are respectively supported by the free ends, or downstream ends, of the plates 511a and 511b via the bearings 515a and 515b.
The swing arms 520a and 520b, like the plates 511a and 511b, are respectively supported by the fulcrums 510a and 510b at their upstream ends in the direction of conveyance. The second spring 521 is anchored to the downstream ends of the swing arms 520a and 520b in the direction of- conveyance at opposite ends thereof, constantly biasing the ends of the swing arms 520a and 520b toward each other. As shown in
In the above configuration, when the bearings 515a and 515b of the fold rollers 81a and 81b are moved away from each other by a preselected distance, the bearings 515a and 515b respectively abut against the inner edges of the swing arms 520a and 520b facing each other and are therefore subject to the biasing force of the second spring 521. Before the bearings 515a and 515b abut against the above edges of the swing arms 520a and 520b, the fold rollers 81a and 81b are subject to the biasing forces of the first springs 512a and 512b.
More specifically, the bias of the second spring 521 is selected to be heavier than the bias of the first springs 512a and 512b. Therefore, when a sheet stack enters the nip between the fold rollers 81a and 81b, the comparatively light bias of the springs 512a and 512b acts on the sheet stack. Subsequently, when the bearings 515a and 515b of the fold rollers 81a and 81b abut against the swing arms 520a and 520b, respectively, the comparatively heavy bias of the spring 521 acts on the sheet stack. In this configuration, the play between the position where the fold rollers 81a and 81b contact each other and the position where the bearings 515a and 515b respectively contact the swing arms 520a and 520b plays an essential role in introducing a sheet stack to the nip between the fold rollers 81a and 81b.
The drive motor 164 assigned to the fold rollers 81a and 81b and a drive transmission mechanism associated therewith are used because the fold rollers 81a and 81b not only fold a sheet stack, but also convey it. The drive transmission mechanism is implemented as a reduction gear train including gears 552, 551b and 551a held in mesh with a gear mounted on the output shaft of the drive motor 164. The gears 551b and 551a are respectively held in mesh with gears 550b and 550a, which are respectively coaxial with the fold rollers 81a and 81b, causing the fold rollers 81a and 81b to rotate at the same speed as each other.
The cancel links 570, respectively positioned on the inner surfaces of the front and rear side walls, move back and forth along the locus 501 in interlocked relation to the fold plate 74. The release links 570 cancel the pressure acting on the fold rollers 81a and 81b by regulating the positions of the swing arms 520a and 520b. More specifically, the connecting members 524a and 524b respectively connect the swing arms 520a and 520b and a movable shaft 523 positioned downstream of the fold rollers 81a and 81b in the direction of conveyance, thereby relating the position of the cancel links 570 and swing arms 520a and 520b. In this condition, the positions of the cancel links 570 determine the timing for exerting pressure on a sheet stack and the timing for canceling it.
The movable range of the shaft 523 is determined by the dimension of a guide slot 530, which extends in parallel to the locus 501, in the direction of the locus 501. The movable range of the shaft 523 regulates the maximum gap between the fold rollers 81a and 81b. A path 560 along which a sheet stack is conveyed in a folded position is positioned such that the locus 501 is located at the center of the gap. The guide slot 530 that determines the movable range is only illustrative. Alternatively, the connecting members 524a and 524b each may be connected the swing arm 520a or 520b by a single member, in which case the connecting portion will be implemented as a slot having a preselected dimension.
In the above configuration, the movement of the shaft 520 in the direction of sheet discharge is regulated by the dimension of the guide slot 530, so that gaps or plays 523a and 523b are available between the swing arms 520a and 520b and the bearings 515a and 515b at fold roller pressing portions 522a and 522b. In this condition, the transfer of the bias of the first spring 521 is regulated.
The second springs 512a and 512b each may be replaced with a compression spring inserted in the fold roller pressing portion 522a or 522b so as to exert the comparatively light bias. The dimension of each of the gaps 523a and 523b is determined by the position of the downstream end of the guide slot 530 in the direction of conveyance. It follows that the amount of play and the maximum gap between the fold rollers 81a and 81b are determined by the position of the slide guide 530 and the dimension of the cancel link 570 in the direction of movement.
The shaft 523 is connected to each cancel link 570, as stated earlier. Therefore, when the cancel link 570 is moved in a direction indicated by an arrow U, the swing arms 520a and 520b each swing in a direction indicated by an arrow V with the result that a space is formed between each swing arm 520a or 520b and the associated bearing 515a or 515b at the fold roller pressing portion 522a or 522b. Consequently, the transfer of the bias of the first spring 521 is canceled.
As shown in
The fold roller pair 81 and lower outlet roller pair 83, once stopped in the positions shown in
When the pass sensor 323 senses the leading edge of the folded sheet stack, the fold plate 74 is retracted by a preselected distance, as shown in
X=({square root}2−1)R
The above position is derived from the relative position between the sheet stack and the fold roller pair 81 and fold plate 74 and is not limited to X mm.
To effectively sharpen the fold of a sheet stack, the rotation of the fold roller pair 81 in opposite directions, as shown in
After the belt HP sensor 311 has sensed the belt 52 reached its home position, the CPU 360 drives the discharge motor 157 so as to move the belt 52 to the stand-by position. Also, after the jogger fence HP sensor has sensed the logger fence 53 brought to its home position, the CPU 360 moves the jogger fence 53 to the stand-by position. Further, the CPU 360 moves the guide plate 54 and movable guide 55 to their home positions (steps S603 through S605). Subsequently, if the inlet sensor 301 has turned on and then turned off (steps S606 and S607), if the staple outlet sensor 305 has turned on (step S608), and if the shift outlet sensor 303 has turned off (step S609), then the CPU 360 determines that a sheet is present on the staple tray F. The CPU 360 then turns on the knock solenoid 170 over a preselected period of time to bring the knock roller 12 into contact with the sheet and then urges it toward the rear fence 51, thereby positioning the trailing edge of the sheet (step S610).
After the step S610, the CPU 360 drives the jogger motor 158 to move the jogger fence 53 inward by a preselected distance, thereby positioning the sheet in the widthwise direction. The CPU 360 then returns the jogger fence 53 to the stand-by position (step S611). As a result, the sheet on the tray F is positioned in both of the horizontal and vertical directions.
After the last sheet of a single set or copy has been positioned on the staple tray F (YES, step S612), the CPU 360 moves the jogger fence 53 inward by the preselected distance to thereby prevent the edge of the sheet stack from being dislocated (step S613). The CPU 360 then drives the discharge motor 157 in order to move the belt 52 by a preselected amount (step S614), so that the sheet stack is raised to the position where the center staplers S2 are positioned. In this condition, the center staplers S2 staple the sheet stack at the center (step S615).
Subsequently, the CPU 360 causes the belt 52 to move by a preselected amount (step S616) and moves the guide plate 54 and movable guide 55 by a preselected amount each, thereby clearing the path extending to the fold tray G (step S617). At the same time, the CPU 360 causes the upper and lower roller pairs 71 and 72 of the fold tray G to start rotating (step S618). After the movable rear fence 73 of the fold tray G has reached its home position, the CPU 360 causes it to move to the stand-by position (step S619).
After the fold tray G has been prepared for the entry of the sheet stack by the above steps, the CPU 360 causes the belt 52 to move by a preselected amount (step S520) until the sheet stack has been nipped by the discharge roller 56 and press roller 57 and conveyed toward the fold tray G thereby. After the leading edge of the sheet stack has reached the arrival sensor 321 (step 5621) and then further conveyed by a preselected distance, the CPU 360 causes the upper and lower roller pairs 71 and 72 to stop rotating (step S622) and moves the guide plates 51 and 52 to their home positions (step S623). When the sheet stack is fully conveyed by the preselected distance, the CPU 360 causes the roller pairs 71 and 72 to stop rotating for thereby interrupting the conveyance of the sheet stack (step S624). The CPU 360 then releases the lower rollers 72 from each other (step S625).
After the step S625, the CPU 360 determines the number of sheets stapled together (step S625). If the number of sheets is five or less (YES, step S626), then the CPU 360 causes the fold plate 74 to move forward to a position 3 mm short of the nip of the fold roller pair 81 while pushing the sheet stack (step S627). If the answer of the number of sheets is six or more (NO, step 5626), then the CPU 360 causes the fold plate 74 to move to a position 1 mm short of the nip of the fold roller pair 81 while pressing the sheet stack (step S628). Further, the CPU 360 causes the fold roller pair 81 and lower roller pair 83 to start rotating forward (step S629) while stopping the movement of the fold plate 74 (step S630). In this condition, the CPU 360 causes the fold roller pair 81, and lower roller pair 83 to rotate forward by a preselected amount each (
When the pass sensor 323 turns on on sensing the passage of the center-folded sheet stack (step S633;
After the step S638, the CPU 360 causes the fold roller pair 81 and lower roller pair 83 to start rotating forward (step S639) and then causes them to stop rotating when the leading edge of the sheet stack moves away from the pass sensor 323 (YES, step S640). Thereafter, the steps S635 through S641 are repeated. When the preselected operation under way at the upstream side ends or the arrival sensor 321 turns on (YES, step S635) and if the counter reaches the preselected count (YES, step S636), the CPU 360 causes the fold roller pair 81 and lower 6 roller pair 83 to rotate forward (step S642) and returns the fold plate 74 to the home position (step S643). As soon as the arrival sensor 321 turns off (YES, step S644), the CPU 360 presses the lower rollers 72 against teach other to thereby prepare them for the entry of the sheet stack (step S645).
In the above condition, the pass sensor 323 monitors the passage of the sheet stack (steps S646 and S647). When the trailing edge of the sheet stack moves away from the pass sensor 323 (YES, step S647), the CPU 360 causes the fold roller pair 81 and lower roller pair 83 to further rotate over a preselected period of time and then stop (step S648). The CPU 360 then moves the belt 52 and jogger fence 63 to their stand-by positions (steps S 649 and S650). Subsequently, the CPU 360 determines whether or not the sheet stack is the last set or copy to be dealt with by the job (step S651). If the answer of the step S651 is NO, then the CPU 360 returns to the step S606. If the answer of the step 5651 is YES, then the CPU 360 returns the movable rear fence 73, belt 52 and jogger fence 53 to their home positions (steps S652, S653 and S654), causes the inlet roller pair 1, roller pairs 2, 7, 9 and 10, staple outlet roller pair 11 and knock roller 12 to stop rotating (step S655), and turns off the solenoid assigned to the path selector 15 (step S656). This is the end of the procedure shown in
As stated above, the illustrative embodiment has various advantages, as enumerated below.
(1) A single fold roller pair 81, which is rotated in opposite directions, suffices for sharpening the fold of a sheet stack. In addition, the rotation of the fold roller pair 81 occurs within the range of the nip to thereby prevent a sheet stack from moving away from the nip, so that the fold can be sharpened by simple control.
(2) The user can select a desired degree of fold sharpening in accordance with the sheet size and the number of sheets constituting a single stack. This insures an attractive bound sheet stack.
(3) Only the portion relating to fold sharpening is caused to move back and forth, allowing the fold to be most efficiently sharpened.
(4) The rotation of the fold roller pair 81 is controlled on the basis of the output of the pass sensor 323, preventing errors in conveyance length from accumulating. This allows only the target range of the sheet stack to be accurately pressed and therefore promotes efficient sharpening.
(5) The fold roller pair 81 is rotated in the reverse direction at least once, so that the minimum degree of sharpening is achievable without regard to the number of sheets. It follows that the bound sheet stack is attractive without regard to the number of sheets constituting it.
(6) Even if the fold of the sheet stack slips out of the nip of the fold roller pair 81 when the roller pair 81 is reversed, the fold plate held at the stand-by position catches the sheet stack. Therefore, only if the fold roller pair 81 is again rotated forward, the fold of the sheet stack can again easily enter the nip of the roller pair 81 in a short period of time without jamming the path.
Various modifications will become possible for those skilled in the art after receiving the teachings of the present disclosure without departing from the scope thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2002-003650 | Jan 2002 | JP | national |
| 2002-017527 | Jan 2002 | JP | national |
| 2002-351507 | Dec 2002 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10339304 | Jan 2003 | US |
| Child | 11130118 | May 2005 | US |
