Sheet processing apparatus, image forming system and sheet processing method

According to one embodiment, a sheet processing apparatus includes a reinforce roller to further reinforce the fold of a sheet which has been folded by a fold roller pair, a support portion to move the reinforce roller in a direction perpendicular to a sheet conveying direction, a sensor to sense a position of the support portion, a distance sensing portion to sense a distance to a first position and a distance to a second position from a stop position of the support portion, when the sensor senses an abnormal stop of the support portion, and a control unit to compare the distance to the first position and the distance to the second position sensed by the distance sensing portion and to control the support portion to move in a direction where a moving distance is shorter.

FIELD

Exemplary embodiments described herein relate to a sheet processing apparatus, an image forming system and a sheet processing method provided with processing functions, such as, sorting, stapling and reinforcing functions.

BACKGROUND

With respect to the fold of a sheet at the time of reinforcing, sheet processing apparatuses are known which reinforces the fold of a sheet with a reinforce roller unit having a roller separate from a fold roller pair. However in case that the reinforce roller is distant from a home position when an abnormality is sensed, there is a problem that the moving distance of the reinforce roller to the home position is long and thereby a long time is required.

DETAILED DESCRIPTION

In general, according to one embodiment, there is provided a sheet processing apparatus including: a fold roller pair to fold a sheet being pushed into a nip thereof, a reinforce roller to reinforce a fold of the sheet folded by the fold roller pair; a support portion to move the reinforce roller in a direction perpendicular to a sheet conveying direction; a sensor to sense a position of the support portion; a distance sensing portion to sense a distance to a first position and a distance to a second position from a stop position of the support portion, when the sensor senses an abnormal stop of the support portion; and a control unit to compare the distance to the first position and the distance to the second position sensed by the distance sensing portion and to control the support portion to move in a direction where a moving distance is shorter.

Hereinafter, an embodiment of a sheet processing apparatus will be described with reference to the accompanied drawings.

First Embodiment

At the time of the jam, an embodiment compares a distance to a first position and a distance to a second position from a stop position of a reinforce roller for a width of a sheet during a reinforcing operation, and causes the reinforce roller to move in a direction where the moving distance is shorter.

FIG. 1shows a construction of an image forming system composed of a finisher PD as a sheet processing apparatus of a first embodiment and an image forming apparatus PR.FIG. 1shows the whole of the finisher PD and a part of the image forming apparatus PR.

InFIG. 1, the finisher PD is fixed to the image forming apparatus PR, and a recording medium discharged from a sheet discharge port of the image forming apparatus PR is lead to an inlet18of the finisher PD. Here, the recording medium is a sheet. A sheet passes through a path A having finishing means for finishing the sheet, and then is sorted by path selectors15,16into any one of a path B for leading the sheet to an upper tray201, a path C for leading the sheet to a shift tray202, a path D for leading the sheet to a processing tray F (hereinafter referred to also as a staple tray) which aligns, staples or otherwise processes the sheet or sheets.

The sheets led to the staple tray F through the paths A and D and then aligned and stapled in the staple tray F are sorted by a guide plate54and a movable guide55that composes deflecting means into the path C for leading the sheet to the shift tray202and a processing tray G (hereinafter referred to also as a fold processing tray) which folds or otherwise processes the sheets. The sheets which have been folded or otherwise processed in the fold processing tray G are further strongly folded by a reinforce roller unit400, and then are lead to a lower tray203through a path H. In addition, a path selector17is arranged in the path D, and is kept in the state shown inFIG. 1by a low load spring. After the back end of the sheet passes through the path selector17, at least a conveying roller9out of the conveying rollers9,10and a staple outlet roller11, and a refeed roller8are rotated in the reverse direction to thereby lead the back end thereof to a prestacking portion E and to cause the sheet to stay there, and the sheet is conveyed together with the next sheet superposed thereon. Such an operation like this is repeated and thereby two or more sheets can also be conveyed in the superposed state.

On the path A which is mutual to the paths B, C, D, an inlet sensor301to sense the sheet received from the image forming apparatus PR is arranged at the upstream side, and at the down stream side thereof an input roller pair1, a punch unit100, a waste hopper101, a conveying roller pair2, the path selectors15,16are sequentially arranged. The path selectors15,16are maintained in the state shown inFIG. 1by the springs, and when their solenoids are turned ON, the path selector15rotates upward and the path selector16rotates downward to thereby sort the sheet into one of the paths B, C, D.

The finisher PD selectively performs punching (the punch unit100), jogging and edge stapling (jogger fences53and an edge stapler S1), jogging and center stapling (jogger fences53and center staplers S2), sorting (the shift tray202) or center folding (a fold plate74, a fold roller pair81and the reinforce roller unit400) for a sheet or sheets.

A shift tray outlet section I which is located at the most downstream position of the finisher PD includes shift outlet rollers6, a return roller13, a sheet surface sensor330, the shift tray202, a shifting mechanism J shown inFIG. 2and a shift tray elevating mechanism K shown inFIG. 3.FIG. 2is an enlarged perspective view of the main portion indicating the shifting mechanism J, andFIG. 3is an enlarged perspective view of the main portion of the shift tray elevating mechanism K.

InFIGS. 1 and 3, the return roller13contacts a sheet discharged from the shift outlet rollers6and causes the back end of the sheet to abut against an end fence32shown inFIG. 2for thereby aligning it. The return roller13is caused to be rotated by the rotation force of the shift outlet rollers6. A limit switch333is arranged in the vicinity of the return roller13, and when the shift tray202is lifted and raises the return roller13, the limit switch333turns on to cause a tray motor168to stop rotating. This prevents the shift tray202from overrunning. Furthermore, as shown inFIG. 1, the sheet surface sensor330is provided as a sheet surface sensing means which senses a sheet surface position of a sheet or that of a sheet stack discharged out on the shift tray202.

As shown inFIG. 3, the sheet surface censor330has a lever30, a sheet surface sensor330a(for stapling use) and a sheet surface sensor330b(for non-stapling use). The lever30rotates around its shaft portion and has a contact end30awhich makes contact with the top of the back end of a sheet loaded on the shift tray202and a sectorial interrupter30b.

When the sheet surface sensor330a(for stapling use) and the sheet surface sensor330b(for non-stapling use) sense that sheets are stacked on the shift tray202to a prescribed height, the tray motor168is driven to lower the shift tray202by a prescribed amount. The sheet surface position of the sheet stack on the shift tray202is therefore maintained at a substantially constant height.

FIG. 4is a perspective view showing a construction of the outlet section I to the shift tray202.

InFIGS. 1 and 4, the shift outlet roller6has a drive roller6aand a driven roller6b. The driven roller6bis supported at its upstream side in the sheet discharge direction and is supported swingably in the up-and-down direction, and is rotatably supported to the free end of a guide plate33. The driven roller6bcontacts the drive roller6adue to its own weight or a biasing force, and a sheet is nipped between both the rollers6a,6band is discharged.

When a stapled sheet stack is to be discharged, the guide plate33is lifted upward and then lowered at a prescribed timing. This timing is determined on the basis of a sensing signal of a shift outlet sensor303. Its stop position is determined on the basis of a sensing signal of a guide plate sensor331, and the guide plate33is driven by a guide plate motor167. In addition, the guide plate motor167is drive controlled in accordance with the ON/OFF state of a limit switch332.

A construction of the staple tray F for stapling will be described.

FIG. 5is a plan view of the staple tray F as seen from the direction perpendicular to the sheet conveying plane,FIG. 6is a perspective view showing the staple tray F and its driving mechanism, andFIG. 7is a perspective view showing a sheet stack discharging mechanism. As shown inFIG. 6, firstly sheets which are led by the staple outlet roller11to the staple tray F are sequentially stacked on the staple tray F. At this instant, a knock roller12aligns every sheet in the longitudinal direction (a sheet conveying direction), while jogger fences53aligns the sheet in the lateral direction (a direction perpendicular to the sheet conveying direction—sometimes referred to as a sheet width direction). Between consecutive jobs, i.e., during an interval between the last sheet of a sheet stack and the first sheet of the next sheet stack, an edge stapler S1is driven by a staple signal from a control unit to thereby perform a stapling operation. The sheet stack which has been stapled is immediately conveyed to the shift outlet roller6by a discharge belt52with hooks52aand is discharged to the shift tray202which is set at a receiving position.

As shown inFIG. 7, an HP sensor311senses the hook52aof the discharge belt52brought to its home position. The HP sensor311is turned ON/OFF by the hook52a. Two hooks52aare arranged at spaced face-to-face positions on the outer circumference of the discharge belt52, and alternately move and convey the sheet stacks housed on the staple tray F. The discharge belt52can be rotated in the reverse direction such that one hook52aheld in a stand-by position so as to move the sheet stack and the back of the other hook52aat the opposite side align the leading end of the sheet stack housed in the staple tray F in the sheet conveying direction, as needed. The hook52afunction as aligning means of the sheet stack in the sheet conveying direction at the same time.

As shown inFIG. 5, a discharge motor157causes the discharge belt52to move via a discharge shaft65. The discharge belt52and a drive pulley62therefor are positioned at the center of the discharge shaft65in the direction of sheet width. The discharge rollers56are mounted on the discharge shaft65in a symmetrical arrangement. The discharge rollers56rotate at a higher peripheral speed than the discharge belt52.

As shown inFIG. 6, a solenoid170causes the knock roller12to move about a fulcrum12ain a pendulum fashion, so that the knock roller12intermittently acts on the sheets transferred to the staple tray F and causes the sheets to abut against rear fences51. In addition, the knock roller12rotates counterclockwise. The jogger fences53are driven by a jogger motor158rotatable in the forward and reverse directions via a timing belt, and move back and forth in the sheet width direction.

InFIG. 8, the edge stapler S1is driven by a stapler motor159which is rotatable in the forward and reverse directions via a timing belt, and moves in the sheet width direction in order to staple a sheet stack at a prescribed position of the sheet end portion. A stapler HP sensor312to sense the home position of the edge stapler S1is provided at one end of the movable range of the edge stapler S1, and the stapling position in the sheet width direction is controlled in terms of the displacement of the edge stapler S1from the home position. As shown in the perspective view ofFIG. 9, the edge stapler S1is constructed so that a striking angle of a staple can be selectively set in parallel to or obliquely to the edge portion of the sheet, and so that only the stapling mechanism portion of the edge stapler S1at the home position is made rotatable by a prescribed angle obliquely so as to replace staples easily. The edge stapler S1is rotated obliquely by an oblique motor160, and when a sensor313senses that the stapling mechanism has reached a prescribed oblique angle or a staple replacement position, the oblique motor160stops. After oblique stapling is finished or the replacement of staples is finished, the stapling mechanism is rotated to the original position to prepare for next stapling.

As shown inFIGS. 1 and 5, the center staplers S2are arranged by two, fixed to a stay63, and are arranged respectively at positions where the distance between the rear fences51and stapling positions of the center staplers S2are not less than a distance corresponding to one-half of the length of the maximum sheet size that can be center stapled, as measured in the conveying direction, and are arranged symmetrically to each other with respect to the alignment center in the sheet width direction. In the case of center stapling, after a sheet stack is aligned by the jogger fences53in the direction perpendicular to the sheet conveying direction and is aligned in the sheet conveying direction by the rear fences51and the knock roller12, the discharge belt52is driven to lift the back end portion of the sheet stack with its hook52to a position where the center portion of the sheet stack in the sheet conveying direction coincides with the stapling positions of the center staplers S2. The discharge belt52stops at this position and causes the center staplers S2to staple the sheet stack. The stapled sheet stack is conveyed to the fold processing tray G side and is folded at the center.

In the drawings, a symbol64ais a front side wall,64bis a rear side wall, and a symbol310is a sheet sensor to sense the existence or non existence of the sheets on the staple tray F.

FIG. 10andFIG. 11are views, each describing an operation of a moving mechanism of a fold plate74for center folding.

The fold plate74is supported in such a manner that each of elongate slots74aformed in the fold plate74is movably received in one of two pins64cstudded on each of the front and rear side walls64aand64b. In addition, a pin74bstudded on the fold plate74is movably received in an elongate slot76bformed in a link arm76, and the link arm76swings about a fulcrum76a, causing the fold plate74to move in the right-and-left direction inFIGS. 10 and 11. That is, a pin75bstudded on a fold plate cam75is movably received in an elongate slot76cformed in the link arm76, and the link arm76swings in accordance with the rotation movement of the fold plate cam75, and in response to this movement, the fold plate74reciprocates in the direction perpendicular to a lower guide plate91and an upper guide plate92inFIG. 12.

The fold plate cam75is rotated in the direction of an arrow shown inFIG. 10by a fold plate motor166. The stop position of the fold plate cam75is determined by sensing both end portions of a semicircular interrupter portion75awith a fold plate HP sensor325.

FIG. 10shows the position of the fold plate74in the home position where the fold plate74is fully retracted from the sheet stack housing range of the fold processing tray G. When the fold plate cam75is rotated in the direction of an arrow, the fold plate74is moved in the direction of the arrow and enters the sheet stack housing range of the fold processing tray G.FIG. 11shows a position where the fold plate74pushes the center of the sheet stack on the fold tray G into the nip between the fold roller pair81. When the fold plate cam75is rotated in the direction of an arrow, the fold plate74moves in the direction of the arrow and thereby retracts from the sheet stack housing range of the fold processing tray G.

In the first embodiment, with respect to center folding, to fold a sheet stack at the center is assumed, but the first embodiment is also applied to a case to fold a single sheet at the center. In such a case, because a single sheet does not have to be stapled at the center, at a time point when the sheet is discharged, the sheet is fed to the fold processing tray G side, folded by the fold plate74and the fold roller pair81, and then discharged to the lower tray203.

Next, the reinforce roller unit400will be described. As shown inFIG. 1, the reinforce roller unit400is provided on the path H between the fold roller pair81and an outlet roller pair83. The sheet stack which has been folded by the fold plate74is pushed into the nip of the fold roller pair81and folded, and then the fold thereof is reinforced by the reinforce roller unit400.

As shown in a plan view ofFIG. 13and a side view ofFIG. 14, the reinforce roller unit400has a reinforce roller409, a support mechanism of the reinforce roller409, and a drive mechanism of the reinforce roller409. The drive mechanism of the reinforce roller409includes a drive pulley402, a driven pulley404, an endless timing belt403which is passed over both the pulleys402and404, and a pulse motor401for driving the timing belt403(FIG. 14) to rotate.

The support mechanism of the reinforce roller409includes a support portion407which is connected with and moves integrally with the timing belt403, a guide portion405which the support portion407slides with and regulates the moving direction, an upper guide plate415which extends to the opposite side of the reinforce roller of the support portion407, regulates the tilt of the reinforce roller409, and prevents the guide portion405from bending, a roller support portion408, a biasing member411(a coil spring inFIG. 14) as biasing means for biasing the reinforce roller409toward the folding direction of the sheet stack (downward inFIG. 13,FIG. 14). The support mechanism is arranged in the direction perpendicular to the sheet conveying direction, and the drive mechanism causes the reinforce roller409to move inside the support mechanism in the direction in which the support mechanism is arranged.

The rotation driving force of the pulse motor401is transferred to the support portion407connected with the timing belt403, via the timing belt403which is passed over the drive pulley402and the driven pulley404, and the support portion407is guided by the guide portion405and moves while sliding in the thrust direction of the guide member405. A bend-preventing portion406is provided between the support portion407and the upper guide plate415, and is rotatably supported to the support portion407, and being roller-shaped, the bend-preventing portion406can move integrally with the support portion407in the axial direction of the guide portion405. The reinforce roller409is arranged between the support portion407and a lower guide plate416, and a friction portion410is fitted on the circumference of the reinforce roller409. The reinforce roller409moves back and forth.

The rotation axis of reinforce roller409is supported by the roller support portion408, and the roller support portion408is supported in such a manner as to be movable in the up-and-down direction in sliding contact with the support portion407. In addition, the roller support portion408is pressurized from the support portion407toward the lower guide plate416by the biasing member411. In this configuration, the reinforce roller409can move in the thrust direction of the guide portion405, integrally with the support portion407, and during this time, the reinforce roller409is constantly pressurized toward the lower guide plate416by the biasing member411, and moves in the up-and-down direction. In addition, a position sensor412and a position sensor413are provided at opposite sides in the thrust direction of the guide portion405, as sensing means for sensing the position of the support portion407. In case that the support portion407is positioned at positions of the position sensor412and the position sensor413, the position sensors412,413sense the support portion407, respectively. A sheet stack sensor414senses a sheet stack conveyed to the reinforce roller unit400.

The position sensor413senses the home position of the reinforce roller409. After the sheet stack is conveyed to the prescribed position and stops, the reinforce roller409is moved from the position of the position sensor413to that of the position sensor412to perform the reinforcing operation. In this time, the number of pulses is counted, and in case that the reinforce roller409is not sensed by the position sensor412after counting a prescribed number of the pulses, that an abnormality (lock of the mechanism, stop due to an insufficient driving torque, step-out of the motor) occurs during the movement of the reinforce roller409is judged.

When judged to be abnormal, the pulse motor401is reversely rotated so as to return the reinforce roller409in the direction of the position sensor413. In this time, an occurrence of a jam is displayed on the display portion.

FIG. 15is a block diagram showing a control of the sheet processing apparatus. A control unit1500has a CPU1501and an I/O interface1502. Signals from switches and so on of the control panel of the image forming apparatus PR and signals from sensors1503are inputted into the CPU1500via the I/O interface1502. The CPU1501controls to drive a solenoid1504and a motor1505on the basis of the inputted signals.

Signals from the inlet sensor301, the shift outlet sensor303, the sheet surface sensor330, the guide plate sensor331, the sheet sensor310, the HP sensor311, the stapler HP sensor312, the staple changing position sensor313, the fold plate HP sensor325, the position sensor412, the position sensor413and the sheet stack sensor414, for example, are inputted to the CPU1501.

In order to control the finisher PD, the abnormality sensing control, and the display control for a display1507, the CPU1500executes the program written in a memory1506. In addition, a CPU provided in the image forming apparatus PR executes a display control for an operation and display unit in the image forming apparatus PR, in accordance with the control output of the CPU1501.

Hereinafter, a series of flow will be described from the time of the occurrence of abnormality. Even if the pulse motor401is driven to cause the reinforce roller409to move in the direction of the position sensor413, the position sensor413is not turned ON in a prescribed time, this state means that a jam is generated and an abnormality occurs. In this time, a display showing that a jam is generated is made on the operating portion of the image forming apparatus PR. In addition, the finisher PD may have the display1507to display that a jam is generated. Here, the term “jam” means to become in a state in which the reinforce roller409stops abnormally during the reinforcing operation by the reinforce roller409and the sheet can not be conveyed.

FIG. 16is a view showing the reinforce roller409to return the reinforced distance. The moving distance of the reinforce roller409in the direction perpendicular to the sheet conveying direction is judged by the count of the number of steps driven by the pulse motor401, after the position sensor412and the position sensor413are turned OFF. If the reinforce roller409stops at the position shown inFIG. 16at the time of the jam, the count of the number of steps after the position sensor413is turned OFF is not more than the number of steps of a half of the driven distance of the reinforce roller409, and that the reinforce roller409is located at a position near the home position that is the retract position is judged.

When that the reinforce roller409is located at a position near the home position is judged, the reinforce roller409moves in the direction of an arrow a as shown inFIG. 16. The reinforce roller409moves to the outside of the width of the sheet during processing, and thereby returns to the home position as shown inFIG. 14. But even though the reinforce roller409is not located at the home position, the reinforce roller409may move to the outside of the width of the sheet during processing and thereby move to a retracting position.

If the reinforce roller409stops at the position shown inFIG. 17at the time of the jam, the count of the number of steps after the reinforce roller409returns and the position sensor412is turned OFF is not more than the number of steps of a half of the driven distance of the reinforce roller409, and that the reinforce roller409is located at a position near the position (a return position) opposite to the home position is judged. In addition, even though the count of the number of steps after the position sensor413is turned OFF is not less than the number of steps of a half of the driven distance of the reinforce roller409, that the reinforce roller409is located at a position near the position opposite to the home position is judged. The CPU1501executes the position judgment and control of the reinforce roller409based on the number of steps.

When that the reinforce roller409is located at a position near the position opposite to the home position is judged, the reinforce roller409moves in the direction of an arrow b as shown inFIG. 17. The reinforce roller409moves to the outside of the width of the sheet during processing, and thereby moves to the position opposite to the home position as shown inFIG. 18. But even though the reinforce roller409is not located at the position opposite to the home position, the reinforce roller409may move to the outside of the width of the sheet during processing and thereby move to the retracting position. After the reinforce roller409is retracted, a user removes the sheet. After the jam is released, the reinforce roller409automatically returns to the home position.

The means for counting the moving distance is provided not only by counting the number of steps driven by the pulse motor401that is a distance sensing portion, but also the moving distance of the reinforce roller409may be counted by an encoder. For example, the drive pulley402or the driven pulley404may be provided with a rotary encoder to detect the moving distance, or the upper guide plate415may be provided with a linear encoder to detect the moving distance.

By sensing the moving distance, a distance to a first position and a distance to a second position for the sheet width respectively from the reinforce roller409which stops at the time of the jam can be sensed. If the distance to the first position is shorter than the distance to the second position for the sheet width, the reinforce roller409moves to the first position. On the other hand, if the distance to the second position is shorter than the distance to the first position for the sheet width, the reinforce roller409moves to the second position. The fist position is the home position and the second position is the position opposite to the home position, for example. However, the fist position may be the position opposite to the home position and the second position may be the home position.

With the above-described construction, the processing time to move the reinforce roller409to the retract position can be shortened.

Second Embodiment

In a second embodiment, in addition to the first embodiment, the lower guide plate416has a plurality of retract positions. The same symbols are given to the same constituent components as in the first embodiment.

FIG. 19is a view showing the lower guide plate416having a plurality of retract positions1900in the second embodiment. The lower guide plate416has two or more roller retract positions1900other than the home position. InFIG. 19, the lower guide plate416has two retract positions1900in addition to the home position and the position opposite to the home position. After an abnormality is sensed, the reinforce roller409moves to the nearest retract position. When the abnormality is sensed, the reinforce roller409preferably moves to the retract position locating in the direction reverse to its moving direction. But in case that the retract position1900is not present at the side opposite to the moving direction of the reinforce roller409, the torque is raised to cause the reinforce roller409to move to the nearest retract position.

After confirming the jam at the reinforce roller409with the display screen of the display1507, a user pushes a reinforce roller fixing release button. Then the lower guide plate416moves in the direction to separate from the reinforce roller409, or the reinforce roller409moves in the direction to separate from the lower guide plate416, and thereby the lower guide plate416and the reinforce roller409are released from their high pressure state. The solenoid is turned ON and OFF thereby to cause the lower guide plate416and the reinforce roller409to move. The solenoid is controlled by the control unit1500.

In addition, position sensors1901,1901are preferably provided at the retract positions1900,1900, respectively. In addition, the retract positions1900,1900may be at stapling positions1902,1902, respectively.

With the above-described construction, the processing time to move the reinforce roller409to the retract position can be more shortened. In addition, by making the retract positions1900at the stapling positions1902, respectively, the reinforce roller409can also be protected.