Sheet process apparatus

Information

  • Patent Grant
  • 6264189
  • Patent Number
    6,264,189
  • Date Filed
    Monday, November 16, 1998
    25 years ago
  • Date Issued
    Tuesday, July 24, 2001
    22 years ago
Abstract
The present invention provides a sheet process apparatus comprising a sheet discharge means for discharging a sheet, a first stacking means for stacking the sheet discharged by the sheet discharge means, a bundle discharge means for discharging a sheet bundle rested on the first stacking means, and a second sheet stacking means for stacking the sheet bundle discharged by the bundle discharge means. Wherein the number of sheets in the sheet bundle to be discharged onto the second stacking means is selected to become smaller, when a sheet size in a sheet conveying direction is great, than when a sheet size in the sheet conveying direction is small.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention relates to a sheet process apparatus, and more particularly, it relates to a sheet process apparatus in which, after imaged sheets discharged from an image forming apparatus such as a copying machine, a printer and the like are aligned or stapled, the sheets are stably discharged onto a stacking means.




2. Related Background Art




There has been proposed a sheet process apparatus in which, sheets discharged on a process tray (first stacking means) are aligned or stapled, the sheets are discharged onto a stack tray (second stacking means). In such a process apparatus, in case of a non-stapled sheet bundle in which a sheet bundle discharged on the stack tray is not stapled by a stapler, if the number of sheets in the sheet bundle is too great, upper several sheets in a sheet bundle already stacked on the stack tray may be disordered to worsen the stacking ability. Thus, to avoid this, in the past, the number of the sheets in the bundle has been selected to be relatively small.




However, in the conventional sheet process apparatus, the number of non-stapled sheets discharged from the process tray was the same or constant (for example, several sheets) regardless of the size of the sheet. Thus, when a length of the sheet in a sheet conveying direction is small, the sheets can stably be discharged onto the stacking means; however, when a length of the sheet in the sheet conveying direction is great, the weight of the sheet bundle may push out the sheet bundle already stacked on the stacking means to worsen the stacking ability.




SUMMARY OF THE INVENTION




An object of the present invention is to provide a sheet process means in which a sheet bundle including a large number of sheets can be discharged on a second stacking means without disordering already stacked sheets.




A sheet process apparatus according to the present invention comprises a sheet discharge means for discharging a sheet; a first stacking means for stacking the sheet discharged by the sheet discharge means; a bundle discharge means for discharging a sheet bundle rested on the first stacking means; and a second sheet stacking means for stacking the sheet bundle discharged by the bundle discharge means. And, wherein the number of sheets in the sheet bundle to be discharged onto the second stacking means is selected to become smaller, when a sheet size in a sheet conveying direction is great, than when a sheet size in the sheet conveying direction is small.




Concretely, the number of sheets in the sheet bundle discharged from the bundle discharge means is selected to a larger number as small size when the sheet size in the sheet conveying direction is smaller than 200 mm and 200 mm to 400 mm, and to a smaller number as large size when the sheet size in the sheet conveying direction is greater than 400 mm. Meanwhile, the number of sheets in the sheet bundle discharged from the bundle discharge means is selected to a larger number as small size when the sheet size in the sheet conveying direction is B5 size, A4 size and LTR size and R-type size such as B5R size, A4R size and LTRR size, and to a smaller number as large size when the sheet size in the sheet conveying direction is A3 size, B4 size and LEGL size.




An image forming apparatus according to the present invention comprises an image forming means; a sheet discharge means for discharging a sheet on which an image was formed, a first stacking means for stacking the sheet discharged by the sheet discharge means; a bundle discharge means for discharging a sheet bundle rested on the first stacking means; a second stacking means for stacking the sheet bundle discharged by the bundle discharge means; a sheet size detect means for detecting a size of the sheet; and a number counting means for counting the number of sheets discharged onto the first stacking means. And, wherein the number of sheets in the sheet bundle discharged from the first stacking means to the second stacking means is selected to become smaller, when a sheet size in a sheet conveying direction is great, than when a sheet size in the sheet conveying direction is small, on the basis of detection of the sheet size detect means and counting of the number counting means.




With the above-mentioned arrangement, the plurality of sheets are discharged onto the first stacking means by the sheet discharge means, and the sheet bundle on the first stacking means is discharged onto the second stacking means by the bundle discharge means. The number of the sheets in the sheet bundle to be discharged onto the second stacking means is determined in accordance with the length of the sheet in the sheet conveying direction (for example, about five when the length is small, and, about three when the length is great). In this way, the discharged sheet bundle is prevented from disordering the already stacked sheets by its own weight, thereby improving the sheet stacking ability for stacking the sheets onto the second stacking means.




Further, the number of the sheets in the sheet bundle may be determined in accordance with sheet groups (for example, small size group such as B5, A4 and LTR size, R-type size group such as LTRR, A4R and B5R size, and large size group such as B4, A3 and LEGL size).




According to the present invention, since the number of the sheets in the sheet bundle discharged from the first stacking means is determined on the basis of the length of the sheet in the sheet conveying direction and the determined sheets are discharged onto the second stacking means as the sheet bundle, the already stacked sheets on the second stacking means are not disordered, thereby stably discharging the sheet bundle onto the second stacking means.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a front view of a sheet process apparatus according to the present invention;





FIG. 2

is a side view showing a stapler and a process tray portion;





FIG. 3

is a plan view of a stapler shifting mechanism, looked at from a direction III in

FIG. 2

;





FIG. 4

is a back view of the stapler, looked at from a direction IV in

FIG. 2

;





FIG. 5

is a longitudinal side view showing a rock guide and a process tray;





FIG. 6

is a back view showing the process tray and an align wall shifting mechanism;





FIG. 7

is a plan view of a retractable tray;





FIG. 8

is a plan view of a stack tray shifting mechanism;





FIG. 9

is a view showing arrangement of sensors around a stack tray;





FIG. 10

is a view for explaining an operation of the sheet process apparatus in a non-sort mode;





FIGS. 11

,


12


,


13


,


14


,


15


,


16


,


17


,


18


A and


18


B are views for explaining an operation of the sheet process apparatus in a staple sort mode;





FIGS. 19 and 20

are views for explaining an operation of the sheet process apparatus in a sort mode;





FIG. 21

is a front view of an image forming apparatus to which the sheet process apparatus according to the present invention can be applied;





FIGS. 22A

,


22


B and


22


C are plan views showing a bundle discharge roller pair and a stack tray portion and further showing a small size sheet, an R-type size sheet and a large size sheet, respectively; and





FIG. 23

is a control block diagram of the sheet process apparatus according to the present invention.











DESCRIPTION OF THE PREFERRED EMBODIMENTS




Now, preferred embodiments of a sheet process apparatus according to the present invention and an image forming apparatus having such a sheet process apparatus will be fully explained with reference to the accompanying drawings.




First of all, an image forming apparatus according to the present invention (in this case, including a sheet process apparatus) will be described.





FIG. 21

is a schematic sectional view showing an example of an image forming apparatus (copying apparatus) having a sheet process apparatus according to a preferred embodiment of the present invention.




In the apparatus, a main body


300


of the image forming apparatus (copying apparatus) is provided with an original reading portion (comprised of an original resting plate


401


such as a platen glass, a light source


42


and a lens system


403


) for reading an original D automatically supplied by an automatic original supply device (RDF)


400


, a sheet supply portion


500


for supplying a sheet P on which an image is to be formed, an image forming portion


600


, and a sheet process apparatus


1


for processing and stacking the imaged sheets P discharged from a pair of discharge rollers (discharge means)


302


.




The sheet supply portion


500


includes cassettes


501


,


502


containing the sheets P and detachably mounted to the main body


300


, and a deck


504


disposed on a pedestal


503


. The image forming portion


600


includes a cylindrical photosensitive drum


601


around which a first charger


602


, an exposure portion


603


, a developing device


604


, a transfer charger


605


, a separation charger


606


and a cleaner


607


are disposed. A fixing device


608


is disposed at a downstream side of the image forming portion


600


with the interposition of a convey device


301


therebetween.




Next, an operation of the image forming apparatus


300


will be described.




When a sheet supply signal is outputted from a control device


310


of the image forming apparatus


300


, the sheet P is supplied from the cassettes


501


,


502


or the deck


504


of the sheet supply portion


500


. On the other hand, an image of an original D rested on the original resting plate


401


is read by light from the light source


402


, and light reflected from the original is illuminated onto the photosensitive drum


601


through the lens system


403


. The photosensitive drum


601


was previously charged by the first charger


602


. When the light is illuminated on the photosensitive drum, an electrostatic latent image is formed on the drum. The latent image is developed by toner from the developing device


604


to form a toner image.




Skew-feed of the sheet P supplied from the sheet supply portion


500


is corrected by a pair of regist rollers


505


, and the sheet is supplied to the image forming portion


600


at a predetermined timing. Then, in the image forming portion


600


, the toner image formed on the photosensitive drum


601


is transferred onto the sheet P by the transfer charger


605


. Then, the sheet P to which the toner image was transferred is charged with opposite polarity by the separation charger


606


to be separated from the photosensitive drum


601


.




Thereafter, the sheet P is sent, through the convey device


301


, to the fixing device


608


, where the transferred image is permanently fixed. The sheet on which the image was formed is discharged toward the sheet process apparatus


1


by the pair of discharge rollers


302


.




Next, the sheet process apparatus according to the present invention will be explained.




<Brief Explanation of Sheet Process Apparatus>




First of all, main parts of the sheet process apparatus will be described with reference to

FIG. 1

which is a schematic sectional view of the sheet process apparatus.




In the sheet process apparatus (referred to as “finisher” hereinafter)


1


, a pair of inlet rollers


2


serve to receive the sheet discharged from the pair of discharge rollers


302


of the image forming apparatus


300


. A pair of first convey rollers


3


serve to conveyed the received sheet P. An inlet sheet detect sensor


31


serves to detect the passage of the sheet. A punch unit


50


serves to form a hole in the sheet P in the vicinity of the trail end thereof. The sheet P is urged against a large convey roller (referred to as “buffer roller” hereinafter)


5


having a relatively large diameter by means of urging sub-rollers


12


,


13


,


14


disposed around the buffer roller.




A non-sort path


21


and a sort path


22


can be selected alternately by a first switch flapper


11


. A second switch flapper


10


can alternately select the sort path


22


and a buffer path


23


for temporarily storing the sheet P. A sensor


33


serves to detect the sheet P in the non-sort path and a sensor


32


serves to detect the sheet P in the buffer path


23


.




A pair of second convey rollers


6


are disposed in the sort path, and a process tray unit


129


includes an intermediate tray (referred to as “process tray” hereinafter) for collecting the sheets P temporarily and aligning the sheets and for permitting staple process of a stapler


101


of a staple unit


100


. A roller (lower bundle discharge roller at a fixed side, in the illustrated embodiment)


180




a


which forms a part of a pair of bundle discharge rollers (transport means) is disposed at a discharge side of the process tray (first stacking tray)


130


. A pair of first discharge rollers


7


for discharging the sheet P onto the process tray (first stacking tray)


130


are disposed in the sort path


22


. A pair of second discharge rollers


9


for discharging the sheet P onto a sample tray


201


is disposed in the non-sort path


21


.




An upper discharge roller


180




b


is supported by a rock guide


150


so that, when the rock guide


150


is brought to a closed position, the upper discharge roller is urged against the lower bundle discharge roller


180




a


to bundle-discharge the sheets stacked on the process tray


130


onto a stack tray (second stacking means)


200


. A bundle stacking guide


40


serves to support a trail edge (in a bundle discharging direction) of the sheet bundle rested on the stack tray


200


and the sample tray


201


and also acts as an outer frame of the sheet process apparatus


1


.




<Detailed Explanation of Staple Unit>




Next, the staple unit


100


will be fully described particularly with reference to

FIGS. 2

,


3


and


4


.




A stapler (staple means)


101


is secured to a shift plate


103


via a holder


102


. The shift plate


103


has a set of stud shafts


104


,


105


fixed in parallel with trail edges of the sheets stacked on the process tray


130


. Rolling sub-rollers


106


,


107


rotatably attached to the stud shafts


104


,


105


are shiftably engaged by a series of hole-shaped parallel guide rails


108




a


,


108




b


,


108




c


formed in a fixed plate


108


.




The rolling sub-rollers


106


,


107


have flanges


106




a


,


107




a


having a diameter greater than widths of the series of hole-shaped guide rails


108




a


,


108




b


,


108




c


, and three support sub-rollers


109


are provided at a lower part of the shift plate


103


for holding the stapler


101


so that the shift plate


103


can be shifted on the fixed plate


108


along the series of hole-shaped guide rails


108




a


,


108




b


and


108




c.






As apparent from

FIG. 3

, the series of hole-shaped guide rails


108




a


,


108




b


and


108




c


are designed to include a main guide rail hole portion (


108




a


), a left end guide rail hole portion (


108




b


) branched from the left end portion of the main portion and extending in parallel with the main portion, and a right end guide rail hole portion (


108




c


) branched from the right end portion of the main portion and extending in parallel with the main portion. Accordingly, (i) when the stapler


101


is positioned at a left end side, the rolling sub-roller


106


is located at the left end of the rail hole portion


108




b


and the rolling sub-roller


107


is located at the left end of the rail hole portion


108




a


so that the stapler is maintained in a condition that the stapler is inclined rightwardly by a predetermined angle, and (ii) when the stapler is positioned at an intermediate position, the rolling sub-rollers


106


,


107


are both located within the rail hole portion


108




a


to maintain the stapler in a non-inclined condition or parallel condition, and (iii) when the stapler


101


is positioned at a right end side, the rolling sub-roller


107


is located at the right end of the rail hole portion


108




c


and the rolling sub-roller


106


is located at the right end of the rail hole portion


108




a


so that the stapler is maintained in a condition that the stapler is inclined leftwardly by a predetermined angle. Changing of such postures of the stapler


101


is effected by an action cam (not shown).




The staple unit


100


is provided with a position sensor (not shown) for detecting home positions of the stapler


101


. Normally, the stapler


101


is located at the left end home position (front side).




<Detailed Explanation of Stapler Shifting Mechanism>




Next, a mechanism for shifting the stapler


101


will be fully described.




The rolling sub-roller


106


of the shift plate


103


is provided with a pinion gear


106




b


integrally formed with the lower flange


106




a


and an upper belt pulley


106




c


integrally formed. The pinion gear


106




b


is connected to a drive motor M


100


via a drive belt extending between an output pulley of the drive motor and the belt pulley


106




c


and is meshed with a rack gear


110


secured to the fixed plate


108


along the rail hole portion so that the shift plate


103


can be shifted together with the stapler


101


in a width-wise direction of the sheet in accordance with normal and reverse rotations of the drive motor M


100


.




Stopper laying sub-rollers


112


provided on stud shafts


111


extending downwardly from the lower surface of the shift plate


103


serve to rotate a trail end stopper


131


of the process tray


130


in order to prevent interference between the trail end stopper


131


and the stapler


101


(described later).




<Detailed Explanation of Trail End Stopper>




Next, the trail end stopper


131


for receiving and supporting the trail edges of the sheets P rested on the process tray


130


will be fully described.




The trail end stopper


131


is formed to protrude vertically from a stacking surface of the process tray


130


and has an abutment support surface


131




a


for receiving and supporting the trail end of the sheet P. The abutment support surface


131




a


can be rocked downwardly in a direction shown by the arrow around a pivot pin


131




b


provided on a lower surface of the process tray


130


. A main link


132


has a cam surface


132




a


against which the stopper laying sub-roller


112


abuts to urge the cam surface and is positioned by abutting it against an abutment plate


136


. Further, the main link can be rocked around a shaft


134


secured to a frame (not shown) in opposition to a tension spring


135


. A pin


132




b


provided at an upper end of the main link is slidably received in an elongated hole formed in one end of a connection link


133


having the other end pivotally connected to the trail end stopper


131


via a pin


131




c.






Accordingly, in this case, regarding the trail end stopper


131


shifted to a position where the stopper interferes with the stapler


101


as the shift plate


103


is shifted, when the cam surface


132




a


of the main link


132


is pushed by the stopper laying sub-rollers


112


of the shift plate


103


, the trail end stopper is rocked to a non-interference position shown by the two dot and chain line in

FIG. 3

, so that the interference between the stapler


101


and the trail end stopper is avoided. After a staple process (described later) is finished, when the shift plate


103


is returned to the home position, the trail end stopper


131


is also returned to its initial position. In order to hold the trail end stopper


131


in the non-interference position or retard position during the operation of the stapler


101


, a plurality of such stopper laying rollers


112


are provided along the shifting direction of the shift plate


103


.




Staple stoppers


113


(shown by the two dot and chain line in

FIG. 2

) provided with a support surface having the same configuration as the abutment support surface


131




a


of the trail end stopper


131


are disposed on both side surfaces of the holder


102


for holding the stapler


101


, so that, even when the trail end stopper


131


is in the retard position, the trail ends of the sheets can be supported.




<Detailed Explanation of Process Tray Unit>




Next, the process tray unit


129


will be fully described with reference to FIG.


5


.




The process tray unit


129


is constituted by the process tray


130


, the trail end stopper


131


, an align means


140


, the rock guide


150


, retract paddles


160


, the retractable tray


170


and the pair of bundle discharge rollers


180


.




In this case, the process tray


130


is located in an inclined condition that a downstream (in a discharging direction of the sheet bundle) (left in

FIG. 5

) end of the tray becomes higher than an upstream (right in

FIG. 5

) of the tray. The trail end stopper


131


is positioned at the upstream or lower end of the tray, and, the retract paddles


160


and the align means


140


are positioned at an intermediate portion of the tray on both sides thereof, and, the rock guide


150


including the retract paddles


160


and the pair of bundle discharge rollers


180


is positioned at the downstream or upper end of the tray (upper area of the unit). Further, the retractable tray


170


is positioned at the downstream or upper end of the tray (lower area of the unit) above the stack tray


200


. These elements will be described later.




The sheet P discharged from the pair of first discharge rollers


7


is slid on the process tray


130


by its own weight and by the action of the retract paddles


160


(described later) until the trail end of the sheet P abuts against the abutment support surface


131




a


of the trail end stopper


131


.




As mentioned above, the lower bundle discharge roller


180




a


forming the part of the pair of the bundle discharge rollers


180


is positioned at the upper end of the process tray


130


, and the other bundle discharge roller


180




b


which can be engaged by and disengaged from the lower bundle discharge roller


180




a


is positioned at the front and rear part of the rock guide


150


. The pair of bundle discharge rollers


180




a


,


180




b


can be rotated reversibly by a drive motor M


180


.




<Detailed Explanation of Align Means>




Next, the align means


140


will be fully described with reference to

FIGS. 5 and 6

.




A set of align members


141


,


142


constituting the align means


140


are disposed in an opposed relation on the process tray


130


in correspondence to both lateral edges of the sheet P at an upper portion (front portion) and a lower portion (rear portion). The first front align member


141


and the second rear align member


142


have align surfaces


141




a


,


142




a


(perpendicular to the surface of the process tray


130


) for urging and supporting the lateral edges of the sheet, and rack gear portions


141




b


,


142




b


for supporting the rear surface of the sheet. The rack gear portions


141




b


,


142




b


are disposed below the rear surface of the process tray through a set of parallel guide slots


130




a


,


130




b


formed in the process tray


130


in an up-and-down direction (corresponding to the width-wise direction of the sheet P).




That is to say, briefly speaking, the align surfaces


141




a


,


142




a


are disposed on the upper surface of the process tray


130


in the opposed relation, and the rack gear portions are assembled below the rear surface of the process tray for shifting movement in the aligning direction.




Pinion gears


143


,


144


reversibly rotated by drive motors M


141


, M


142


are meshed with the rack gear portions


141




b


,


142




b


so that the first and second align members


141


,


142


can be shifted in the aligning direction. There are provided position sensors (not shown) for detecting home positions of the first and second align members


141


,


142


. Normally, the first align member


141


is positioned at a home position at the upper end side (front side) and the second align member


142


is positioned at a home position at the lower end side (rear side).




<Detailed Explanation of Rock Guide>




Next, the rock guide


150


will be fully described with reference to FIG.


5


.




As mentioned above, the rock guide


150


is provided at its front lower end portion (corresponding to the downstream end or left end in

FIG. 5

) with the upper bundle discharge roller


180




b


which can be urged against the lower bundle discharge roller


180




a


of the bundle discharge roller pair


180


, and a rear lower end portion (corresponding to the upstream end or right end in

FIG. 5

) of the rock guide is pivotally mounted on a support shaft


151


. The rocking movement of the rock guide is controlled by a rotation cam


152


driven by a drive motor M


150


. The rock guide


150


has a home position (closed condition) where the upper bundle discharge roller


180




b


is urged against the lower bundle discharge roller


180




a


, which home position can be detected by a position sensor (not shown).




In a normal condition, when the sheets P are discharged onto the process tray


130


, the roller pair


180


and the guide


150


are shifted to an open condition (that the upper bundle discharge roller


180




b


is separated from the lower bundle discharge roller


180




a


by the upward rocking movement of the rock guide


150


), so that-the discharging and aligning of the sheets are permitted and the operation of the retract paddles (described later) is also permitted. After the process of the sheet bundle is finished, when the sheet bundle on the process tray


130


is discharged onto the stack tray


200


, the roller pair


180


and the guide


150


are shifted to the closed condition (that the upper bundle discharge roller


180




b


is urged against the lower bundle discharge roller


180




a


by the downward rocking movement of the rock guide


150


).




<Detailed Explanation of Retract Paddles>




Next, the retract paddles


160


will be fully described.




The retract paddles


160


are located above the process tray (

FIG. 5

) and are secured to a shaft


161


and can be rotated in an anti-clockwise direction in

FIG. 5

by a drive motor M


160


at a proper timing. A length of each retract paddle


160


is selected to become slightly greater than a distance between the shaft


161


and the surface of the process tray


130


, and a home position (shown by the solid line in

FIG. 5

) of the retract paddle is selected so that the retract paddle does not obstruct the discharging of the sheet P from the pair of first discharge rollers


7


onto the process tray


130


.




In this condition, when the sheet P is discharged onto the process tray


130


, the retract paddles


160


are rotated in the anti-clockwise direction to retract the sheet P discharged on the process tray


130


until the trail end of the sheet abuts against the abutment support surface


131




a


of the trail end stopper


131


. Thereafter, the retract paddles are returned, at a predetermined timing, to the home position detected by the position sensor (not shown).




<Detailed Explanation of Retractable Tray>




Next, the retractable tray


170


will be fully described with reference to

FIGS. 5 and 7

.




The retractable tray


170


is disposed below the lower bundle discharge roller


180




a


of the bundle discharge roller pair


180


and can be extended and retracted in the sheet bundle discharging direction (shown by the arrow X in

FIGS. 5 and 7

) substantially along the inclination of the process tray


130


. That is to say, in an extended position, a tip end of the retractable tray


170


is protruded toward an upper side of the stack tray


200


(as shown by the two dot and chain line in FIG.


5


), and, in a retracted position (home position), the tip end of the retractable tray is retracted inwardly of the lower bundle discharge roller


180




b


(as shown by the solid line in FIG.


5


). The extended condition of the retractable tray


170


is selected so that the gravity center of the sheet P discharged on the process tray


130


does not exceed the extended position, i.e., the tip end portion of the sheet P is not depended downwardly.




The retractable tray


170


is slidably supported by a pair of guide rails


172


secured to a frame


171


, and a rotary cam sub-roller


173


rotated around a shaft


174


is received in a groove


175


formed in the lower surface of the retractable tray


170


. The retractable tray


170


is extended and retracted by rotation of the rotary cam sub-roller


173


effected by a drive motor M


170


. In a normal condition, the retractable tray is located at the home position detected by a position sensor (not shown).




<Detailed Explanation of Stack Tray and Sample Tray>




Next, the stack tray


200


and the sample tray


201


will be fully described with reference to FIGS.


8


and


9


.




The stack tray


200


and the sample tray


201


are used properly on demand. That is to say, the stack tray


200


positioned at a lower side is selected when the sheet bundle is received in the copy output and printer output, and the sample tray


201


positioned at an upper side is selected when the sheet is received in the sample output, interruption output and job mix stack output.




The stack tray


200


and the sample tray


201


are hold by a tray base plate


202


and


203


, respectively and are self-shifted independently in an up-and-down direction by stepping motors M


200


and M


201


secured to the base plates


202


and


203


via attachment frame plates


204


and


205


. In this case, since the stack tray


200


and the sample tray


201


have the same construction, only the stack tray


200


will be explained mainly.




A pair of frames


250


are provided on both vertical ends of the sheet process apparatus


1


, and rack gear members


251


also acting as vertical guide rail portions are attached to the frames. A pair of guide sub-rollers


206


,


207


rotatably provided on a rear end portion extended from one (


202


) (left side regarding the width-wise direction of the sheet) of the tray base plates and a rear end of a rear end portion extended from the attachment frame plate


204


opposed (right side regarding the width-wise direction of the sheet) to the base plate


202


are received in the corresponding guide rail portions, so that the stack tray


200


is held for vertical movement. Further, by engaging a regulating member


208


by a bent end of one of the frames


250


, any play in the width-wise direction of the sheet is absorbed.




On the other hand, rotational output of the stepping motor M


200


is transmitted to a pulley


212


of a drive shaft


213


via a timing belt


211


. A ratchet wheel


215


provided on the drive shaft


213


for only sliding movement and biased by a spring


216


is engaged by a drive gear


214


on the shaft for permitting one-way driving. One of a pair of idler gears


218


provided on both ends of a driven shaft


217


is meshed with the drive gear


214


, and the idler gears


218


are engaged by the rack gear members


251


via lift/lower gears


219


. That is to say, the stack tray


200


can be lifted and lowered through a drive system comprised of such a gear train.




The ratchet wheel


215


provided on the drive shaft


213


and biased toward one direction is arranged so that, when the stack tray


200


is lowered, a foreign matter is not pinched, thereby preventing damage of the gear train. In the illustrated embodiment, a biasing force of the spring


216


is selected to a predetermined value so that, only when the stack tray


200


is lifted, the ratchet wheel is idly rotated in opposition to the biasing force of the spring


216


if the predetermined condition is exceeded, thereby protecting the gear train. In case of the idle rotation, i.e., if abnormality occurs, in order to immediately stop the stepping motor M


200


, a clock slit formed in a flange portion of the drive gear


214


is detected by a sensor S


201


. Incidentally, the sensor S


201


is also used to detect out-of-phase during the normal operation.




Now, sensors for controlling lifted and lowered position of the stack tray


200


and the sample tray


201


will be described.




A sensor S


202


serves to detect a stacking area of the sample tray


201


and detects the fact that the tray is located within a range belonging an area from a lifted position detect sensor S


203




a


to a process tray sheet surface detect sensor S


205


. A sensor S


203




b


serves to detect the fact that the number of sheets P discharged from the pair of second discharge rollers


9


onto the sample tray


201


reaches a predetermined value. In the illustrated embodiment, the sensor S


203




b


is located at a height position corresponding to a thickness of 1000 sheets, above a non-sort sheet surface detect sensor S


204


.




A sensor S


203




c


serves to detect the fact that the number of sheets P discharged from the process tray


130


onto the sample tray


201


reaches a predetermined value. In the illustrated embodiment, the sensor S


203




c


is located at a height position corresponding to a thickness of 2000 sheets, above the sheet surface detect sensor S


205


. A sensor S


203




d


serves to limit a stacking height when the stack tray


200


receives the sheets P from the process tray


130


. In the illustrated embodiment, the sensor S


203




d


is located at a height position corresponding to a thickness of 2000 sheets, above the sheet surface detect sensor S


205


.




A sensor S


203




e


serves to set a lower limit position of the stack tray


200


. The stack tray


200


and the sample tray


201


are provided with sheet presence/absence detect sensors S


206




a


and S


206




b


, respectively.




Among these sensors, only the sheet surface detect sensors S


204


, S


205


are of light permeable type for detecting the presence/absence of the sheet by light from one lateral edge to the other lateral edge of the sheet P. In the illustrated embodiment, as a method for detecting the sheet surfaces, initial positions are determined as conditions that the trays


200


,


201


are lifted from below the sheet surface detect sensors S


204


, S


205


to positions where the sensors are covered by the trays, and, after the sheet is stacked, the trays are lowered until the sensor optical axes are revealed and thereafter the trays are lifted until the sensor optical axes are covered, and such operations are repeated.




<Detailed Explanation of Flow of Sheet P>




When the operator selects a non-sort mode via an operation portion (not shown) of the image forming apparatus, the pair of inlet rollers


2


, the pair of convey rollers


3


and the large convey roller (buffer roller)


5


are rotated as shown in

FIG. 10

to convey the sheet P conveyed from the image forming main body


300


. The flapper


11


is rotated to a position shown in

FIG. 10

by a solenoid (not shown) to convey the sheet P into the non-sort path


21


. After the trail end of the sheet P is detected by the sensor


3




s


, the pair of rollers


9


are rotated at a speed suitable for stacking, thereby discharging the sheet P onto the sample tray


201


.




Next, an operation when the operator selects the staple sort mode will be explained.




The flappers


10


,


11


are stopped at positions shown in FIG.


11


. The pair of inlet rollers


2


, the pair of convey rollers


3


and the large convey roller


5


are rotated to convey the sheet P conveyed from the image forming main body


300


. The sheet P passes through the sort path


22


and is discharged onto the process tray


130


by the pair of first discharge rollers


7


. In this case, since the retractable tray


170


is in the extended position, the tip end of the sheet is prevented from being suspended downwardly when the sheet P is discharged by the pair of first discharge rollers


7


, thereby preventing poor returning and improving the aligning ability of the sheets on the process tray.




The discharged sheet P starts to shift toward the trail end stopper


131


by its own weight, and, the paddle which were stopped at the home position are rotated in the anti-clockwise direction by the motor M


160


to aid the shifting of the sheet. When the trail end of the sheet abuts against the stopper


131


and is stopped there, the paddles


160


are also stopped, and the discharged sheet is aligned by the align members.




After all of the sheets constituting the first part are discharged on the process tray


130


and are aligned to each other, as shown in

FIG. 12

, the rock guide


150


is lowered to urge the upper bundle discharge roller


180




b


against the sheet bundle, and the sheet bundle is stapled by the stapler


101


.




Meanwhile, as shown in

FIG. 12

, the sheet P


1


discharged from the image forming main body


300


is wound around the large convey roller


5


by the rotation of the flapper


10


and is stopped at a position spaced apart from the sensor


32


by a predetermined distance. When a next sheet P


2


advances from the sheet detect sensor


31


by a predetermined distance, as shown in

FIG. 13

, the large convey roller


5


is rotated to advance the second sheet P


2


greater than the first sheet P


1


by a predetermined distance, thereby overlapping the sheets together, and, as shown in

FIG. 14

, the sheets P


1


, P


2


are wound around the large convey roller


5


and the large convey roller is stopped at a predetermined distance. On the other hand, the sheet bundle on the process tray


130


is discharged onto the stack tray


200


. However, in this case, the retractable tray


170


is shifted to the home position before the sheet bundle leaves the pair of bundle discharge rollers, thereby permitting the dropping of the sheet bundle onto the stack tray


200


.




As shown in

FIG. 15

, when a third sheet P


3


reaches a predetermined position, the large convey roller


5


is rotated to overlap the third sheet P


3


with slight distance deviation, and the flapper


10


is rotated to permit the conveyance of three sheets into the sort path


22


.




As shown in

FIG. 16

, in the condition that the rock guide


150


is lowered, three sheets P are received by the bundle discharge rollers


180




a


,


180




b


. As shown in

FIG. 17

, when the trail ends of the sheets leave the pair of first discharge rollers


7


, the bundle discharge rollers


180




a


,


180




b


are rotated reversely. Before the trail end of the sheet bundle abuts against the trail end stopper


131


(FIG.


18


A), as shown in

FIG. 18B

, the rock guide


150


is lifted to separate the roller


180




b


from the sheet surface. Similar to the first part, a fourth sheet and so on are passed through the sort path and are discharged onto the process tray. Regarding a third part and so on, the operation similar to the second part are repeated. In this way, a predetermined number of parts (sheet bundles) are stacked on the stack tray


200


, and then the operation is finished.




In the above-mentioned overlap conveyance of the plurality of sheets, the sheets P are offset from each other in the conveying direction. For example, the sheet P


2


is offset from the sheet P


1


toward the downstream side, and the sheet P


3


is offset from the sheet P


2


toward the downstream side.




A timing between the offset amount of the sheet and the lifting of the rock guide


150


depends upon the settling time of the sheet determined by the returning speed of the bundle discharge roller pair, i.e., the timing is determined on the basis of the processing ability of the image forming main body


300


. In the illustrated embodiment, when the sheet conveying speed is 750 mm/s, offset amount (b) is about 20 mm and returning speed of the bundle discharge roller pair is about 500 mm/s, the separation timing of the bundle discharge roller pair is selected to a time when the sheet P


1


reaches a position in front of the stopper by about 40 mm (value “a” in FIG.


18


A).




<Detailed Explanation of Sort Mode>




The operator sets the originals in the RDF


400


, selects the sort mode via the operation portion (not shown) and turns a start key (not shown) ON. As is in the staple sort mode, the pair of inlet rollers


2


and the pair of convey rollers


3


are rotated as shown in

FIG. 19

similar to the staple sort mode to stack the sheets P on the process tray


130


. After small number of sheets on the process tray


130


are aligned together by the align means


140


, as shown in

FIG. 20

, the rock guide


150


is lowered, so that the small number of sheets are bundle-conveyed by the rollers


180




a


,


180




b.






Then, the conveyed sheet passes over the flapper


10


and is wound around the large convey roller


5


as is in the staple sort mode and is discharged onto the process tray


130


after the bundle-discharge is finished. From tests, it was found that the number of sheets included in the sheet bundle to be bundle-discharged is desirably twenty or less. The number is selected to satisfy the following relation:






Number of originals≧number to be bundle-discharged≦20






Thus, when the program is set so that the number to be bundle-discharged becomes five (5), if the number of originals is four (4), the sheet bundle including four sheets are bundle-discharged. If the number of originals is greater than five, for example, the number of originals is 14, the sheets are aligned and bundle-discharged as groups of five sheets, five sheets and four sheets.




Regarding the second part, the sheets are aligned together at the offset position and are bundle-discharged every small number of sheets similar to the first part. After the second part was processed, the front align member and the rear align member


143


are returned to the position where the first part is aligned and are used to align a third part.




Incidentally, there is an embodiment for reducing an influence of the discharged sheet bundle upon the already stacked sheets by determining the number of sheets included in a non-stapled sheet bundle on the basis of a length of the sheet in a sheet conveying direction, and such an embodiment will be explained with reference to

FIGS. 22A

to


22


C and FIG.


23


.




<Detailed Explanation of Movements of Stack Tray


200


and Sample Tray


201


>




In

FIGS. 8 and 9

, the sample tray


201


and the stack tray


200


are normally waiting at the sheet surface detect sensor positions (normal stacking positions) S


204


, S


205


. The copy output or printer output is normally stacked on the stack tray


200


, and the stack tray can receive the sheets processed by the stapler


101


or the sheet bundle including small number of non-stapled sheets. The tray


200


can receive 2000 sheets at the maximum, and the stacking of the sheets is detected by the sensor S


203




d.






When the copy output from the printer is further continued, the stack tray


200


is lowered from the sensor S


203




d


by a distance corresponding to a thickness of 1000 sheets (to a position shown by “S


203




d


′” in FIG.


9


). Then, the sample tray


201


is lowered up to the sheet surface detect sensor S


205


for the sample tray to start to receive the sheets again. The sample tray


201


can receive 1000 sheets at the maximum, and the stacking of the sheets is detected by the sensor S


203




c.






Then, after the job for 2000 sheets or less is finished, when the next job is started without removing the sheets on the stack tray


200


or when interruption is effected during the present job, the process operation cannot be performed, but, the sheets can be discharged from the non-sort discharge path


21


by using the sample tray


201


. In the normal condition, as mode in which the sheets are outputted to the sample tray


201


by using the non-sort discharge path


21


, there are a mode in which the sheet included in only one part are outputted for sampling without no process and a mode in which sample tray output is set to function sort.




Next, main portions (according to the present invention) of the sheet process apparatus will be explained with reference to

FIGS. 22A

to


22


C and FIG.


23


.




As shown in FIG.


19


and

FIGS. 22A

to


22


C, the small number of non-stapled sheets discharged on the process tray


200


are discharged onto the stack tray


200


by the rotation of the bundle discharge roller pair


180


. The number of non-stapled sheets is determined on the basis of the length of the sheet in the sheet conveying direction.




The sheet bundle P


1


to be discharged as shown in

FIG. 22A

includes sheets having small size such as B5 size, A4 size or LTR size, the sheet bundle P


2


shown in

FIG. 22B

includes sheets having R-type size such as LTRR size, A4R size or B5R size, and the sheet bundle P


3


shown in

FIG. 22C

includes sheets having large size such as B4 size, A3 size or LEGL size. And, the number of sheets included in the sheet bundle is determined on the basis of the above size. For example, in case of the small size sheet bundle P


1


and R-type size sheet bundle P


2


, the number of sheets in the sheet bundle is selected to five, and, in case of the large size sheet bundle P


3


, the number of sheets in the sheet bundle is selected to three.




By determining the number of sheets in the sheet bundle on the basis of the length of the sheet in the sheet conveying direction in this way, the non-stapled sheet bundle can stably discharged without disordering the already stacked sheets.




The size of the sheet stacked on the process tray


200


may be detected by a sheet size detect means S


211


of the image forming main body


300


from which the sheet is supplied to the sheet process apparatus


1


, and the number of sheets in the sheet bundle may be determined on the basis of the detected sheet size. For example, the sheet sizes are grouped into small size (smaller than 200 mm (in length) in the sheet conveying direction), middle size (from 200 mm to 400 mm (in length) in the sheet conveying direction), and large size greater than 400 mm (in length) in the sheet conveying direction), and, in case of the small size sheet bundle and the middle size sheet bundle, the number of sheets in the sheet bundle is selected to five, and, in case of the large size sheet bundle P


3


, the number of sheets in the sheet bundle is selected to three.




On the basis of detection of the size of the sheet by means of the sheet size detect means S


211


and detection of the number of sheets discharged on the process tray


130


by means of a sheet number detect means S


212


, the bundle discharge roller pair


180


is driven by the bundle discharge motor M


180


, thereby discharging the predetermined number of sheets depending upon the sheet size.




The control for determining the number of sheets (to be discharged) depending upon the sheet size is effected by a control apparatus


4


of the sheet process apparatus and a control apparatus


310


of the image forming apparatus, as shown in FIG.


23


.




Incidentally, while an example that the number of sheets in the small size sheet bundle and R-type size sheet bundle is selected to five and the number of sheets in the large size sheet bundle is selected to three was explained, such numbers are only exemplary and do not limit the invention.



Claims
  • 1. A sheet process apparatus comprising:sheet discharge means for discharging a sheet; first stacking means for stacking the sheet discharged by said sheet discharge means; bundle discharge means for discharging a sheet bundle rested on said first stacking means; and second stacking means for stacking the sheet bundle discharged by said bundle discharge means, wherein when a sheet stack is stacked on said second stacking means, a plurality of sheet bundles are successively piled up to form the sheet stack, and wherein a number of sheets in the sheet bundle to be discharged onto said second stacking means when a length of the sheet in a sheet conveying direction is a large size is smaller than a number of sheets in the sheet bundle to be discharged onto said second stacking means when a length of the sheet in the sheet conveying direction is a small size.
  • 2. A sheet process apparatus according to claim 1, wherein the number of sheets in the sheet bundle discharged by said bundle discharge means when the small size of the sheet in the sheet conveying direction is less than 400 mm is a larger number, and the number of sheets in the sheet bundle discharged by said bundle discharge means when the large size of the sheet in the sheet conveying direction is equal to or larger than 400 mm is a small number.
  • 3. A sheet process apparatus according to claim 1, wherein the number of sheets in the sheet bundle discharged by said bundle discharge means when the length of the sheet in the sheet conveying direction corresponds to one of a sheet size of a B5 size, an A4 size an LTR size, and a R-type size, the R-type size being one of a B5R size, an A4R size, and an LTRR size, is a large number, and the number of sheets in the sheet bundle discharged by said bundle discharge means when the length of the sheet in the sheet conveying direction corresponds to one of an A3 size, a B4 size and an LEGL size, is a small number.
  • 4. A sheet process apparatus according to claim 1, further comprising sheet size detecting means provided in an apparatus body from which the sheet is discharged to the sheet process apparatus and for detecting the length of the sheet in the sheet conveying direction, sheet number counting means for counting the number of sheets discharged onto said first stacking means, and control means for controlling a sheet bundle discharging operation of said bundle discharge means on the basis of a detection result of said sheet size detecting means and a counting result of said sheet number counting means.
  • 5. A sheet process apparatus according to claim 1, wherein the number of sheets in the sheet bundle when the length of the sheet for the small size is smaller than 400 mm is five, and the number of sheets in the sheet bundle when the length of the sheet for the large size is equal to or larger than 400 mm is three.
  • 6. A sheet process apparatus according to claim 1, wherein the number of sheets in the sheet bundle when the small size for the length of the sheet is one of a B5 size, an A4 size, an LTR size, a B5R size, an A4R size, and an LTRR size, and the number of sheets in the sheet bundle when the large size for the length of the sheet is one of an A3 size, a B4 size and a LEGL size is three.
  • 7. A sheet process apparatus according to claim 1, wherein, when a desired number of sheets in the sheet stack to be stacked on said second stacking means is N, sheet bundles including the small number of sheets or the large number of sheets are bundle-discharged plural times so that the desired number N of sheets are stacked on said second stacking means.
  • 8. A sheet process apparatus according to claim 7, wherein said bundle discharge means is a pair of upper and lower rotary members for pinching the sheet bundle on said first stacking means and for conveying the sheet bundle to said second stacking means.
  • 9. An image forming apparatus comprising:a sheet process apparatus according to one of claims 1, 2, 3, 4, 5, 6, 7 or 8; image forming means; and conveying means for conveying a sheet on which an image has been formed to said sheet process apparatus.
  • 10. An image forming apparatus comprising:image forming means; sheet discharge means for discharging a sheet on which an image has been formed; first stacking means for stacking the sheet discharged by said sheet discharge means; bundle discharge means for discharging a sheet bundle rested on said first stacking means; second stacking means for stacking the sheet bundle discharged by said bundle discharge means; sheet size detecting means for detecting a size of the sheet; and sheet number counting means for counting a number of sheets discharged onto said first stacking means, wherein when a sheet stack is stacked on said second stacking means, a plurality of sheet bundles are successively piled up to form the sheet stack, and wherein a number of sheets in the sheet bundle discharged from said first stacking means to said second stacking means when a length of the sheet in a conveying direction is a large size is made smaller than a number of sheets in the sheet bundle discharged from said first stacking means to said second stacking means when a length of the sheet in the sheet conveying direction is a small size on the basis of a detection result of said sheet size detecting means and a counting result of said sheet number counting means.
  • 11. An image forming apparatus according to claim 10, wherein the number of sheets in the sheet bundle discharged by said bundle discharge means when the small size of the sheet in the sheet conveying direction is less than 400 mm is a larger number, and the number of sheets in the sheet bundle discharged by said bundle discharge means when the large size of the sheet in the sheet conveying direction is equal to or larger than 400 mm is a small number.
  • 12. An image forming apparatus according to claim 10, wherein the number of sheets in the sheet bundle discharged by said bundle discharge means when the length of the sheet in the sheet conveying direction corresponds to one of a sheet size of a B5 size, an A4 size, an LTR size, and a R-type size, the R-type size being one of a B5R size, an A4R size, and an LTRR size, is a large number, and the number of sheets in the sheet bundle discharged by said bundle discharge means when the length of the sheet in the sheet conveying direction corresponds to one of an A3 size, a B4 size and an LEGL size, is a small number.
Priority Claims (1)
Number Date Country Kind
9-315527 Nov 1997 JP
US Referenced Citations (8)
Number Name Date Kind
4934687 Hayden et al. Jun 1990
5078378 Kapadia et al. Jan 1992
5181705 Ueda et al. Jan 1993
5462265 Mandel et al. Oct 1995
5621501 Matsuo et al. Apr 1997
5961115 Blanck et al. Oct 1999
5997239 Mimura et al. Dec 1999
6032947 Parker Mar 2000