Sheet-material associating – Associating or disassociating – Sheet associating
Reexamination Certificate
1998-07-22
2001-10-23
Ellis, Christopher P. (Department: 3651)
Sheet-material associating
Associating or disassociating
Sheet associating
C270S058120, C270S058130, C270S058170
Reexamination Certificate
active
06305681
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a sheet processing apparatus having a stapler function to staple sheets discharged from an image forming apparatus such as a copying machine, a facsimile, a printer, an offset printer, or the like, and more particularly to a sheet processing apparatus with an open/close switchable sheet discharging member for discharging a non-stapled sheet and stapled sheets.
2. Discussion of the Background
A sheet processing apparatus having a stapler function to staple sheets discharged from an image forming apparatus generally includes a function of stapling sheets and then discharging the stapled sheets, in addition to a function of discharging sheets without stapling. Further, such a sheet processing apparatus generally includes an output tray which receives sheets which are discharged after being stapled and the sheets discharged without being stapled as well.
FIG. 8
is a schematic drawing illustrating a configuration of a sheet processing apparatus disclosed, for example, in Japanese Patent Laid Open Publication No.5-305786. A sheet P conveyed from an image forming apparatus
500
is selectively guided either to a first conveying path
504
for stapling or a second conveying path
506
for discharging the sheet without stapling by an operation of a separation guide pick
502
. The separation guide pick
502
operates in accordance with a selection between stapling and non-stapling modes.
In the stapling mode, the sheet P is guided to the first conveying path
504
and is stacked and aligned on a stack tray
508
. Then, a plurality of the sheets P stacked in the stack tray
508
are stapled by a stapler (not shown) and the stapled sheets are pushed out by a sheets pushing up member (not shown) in the direction indicated by a broken arrow in the drawing and are discharged to an output tray
512
while being supported and sandwiched by a discharging member
510
, provided at an exit of the sheet processing apparatus, for discharging the sheet therefrom. In the non-stapling mode, the sheet P is guided to the second conveying path
506
and discharged to the output tray
512
after being supported and sandwiched by the discharging member
510
.
The discharging member
510
includes a pair of rollers, including a drive roller
514
and a driven roller
516
. The driven roller
516
is selectively brought into and out of contact with the drive roller
514
in the direction indicated by an arrow. When the sheets P are started to be discharged (pushed upward) from the stack tray
508
in the stapling mode, the driven roller
516
moves apart from the drive roller
514
so that the discharging member
510
is in an open condition for discharging the sheets P without sandwiching them. The sheets P are started to be pushed upward through the discharging member
510
in this open condition. A discharging sensor (not shown) is provided adjacent to and upstream in the sheet conveying direction of the discharging member
510
. When the discharging sensor detects the tail end of the sheets, the discharging member
510
changes to a closed condition with the driven roller
516
returned to the position to contact the drive roller
514
. Thereafter, the sheets P are discharged to the output tray
512
being supported and sandwiched by the discharging member
510
.
If the discharging member
510
supports and sandwiches the sheets P at an earlier timing, in other words if the discharging member
510
supports and sandwiches the sheets P from the tip portion of the sheets P in the conveying direction, the following problem arises. As illustrated in FIG.
9
(
a
), when a curl of a stapled stack of sheets P is large, there exists a deviation of placements between the top and bottom sheets in the sheet conveying direction. Because the sheets P are stapled at the tail end parts thereof, the top side sheets of the stapled stack of sheets P gradually bulge resulting from being sandwiched and pressed by the rollers
514
and
516
. As illustrated in FIG.
9
(
b
), a bulge E is transferred toward the tail end parts of the sheets as the bulge E is pressed by the rollers
514
and
516
, but the bulge E cannot be eliminated because the sheets P are stapled at the tail end parts of the sheets. The bulge E is pressed by the rollers
514
and
516
finally. This makes the sheets P thicken in the vicinity of the tail end of the sheets and as a consequence the sheets may not be discharged smoothly through the rollers
514
and
516
. Though the above-mentioned problem is not described in the Japanese Patent Laid Open Publication No.5-305786, it seems that the problem does not exist in the sheet processing apparatus of the above publication because the sheets are started to be supported and sandwiched by the rollers after the discharging sensor provided in the vicinity of the discharging member
510
detects the tail end of the sheets.
However, in the sheet processing apparatus disclosed in the Japanese Patent Laid Open Publication No.5-305786, the discharging member
510
changes to the open condition from the closed condition when the stapled sheets are started to be discharged (pushed out) from the stack tray
508
. Therefore, in order to stack and align sheets of every size in the conveying direction for stapling in the stack tray
508
, a space for accommodating the biggest sized sheet is necessary between the discharging member
510
and the bottom part of the stack tray
508
. Therefore, the apparatus is hard to be made compact, irrespective of the presence or absence of the non-stapling mode. In addition, the first conveying path for stapling and the second conveying path for non-stapling are located apart from each other with an open space existing between them, further making it harder to realize a compact design.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide a sheet processing apparatus that can realize a compact design irrespective of the presence or absence of non-stapling mode using an open/close switching structure of a discharging member for discharging sheets.
A sheet processing apparatus according to the present invention includes a sheet conveying path for receiving a sheet conveyed from the outside and conveying the sheet therethrough to be discharged, a stack tray for stacking a plurality of the conveyed sheets for stapling, a stapling device for stapling the plurality of the sheets stacked on the stack tray, and an output tray for receiving the discharged sheets. The sheet conveying path includes a first conveying path for guiding the conveyed sheet to the stack tray for stapling, and a second conveying path for guiding the conveyed sheet to the output tray bypassing the stack tray. The sheet processing apparatus further includes a discharging member for discharging the conveyed sheet or the sheets guided by the first conveying path or second conveying path, a discharging member switching device which selectively switches the discharging member to a closed condition for discharging the sheet or sheets by sandwiching them or to an open condition for discharging the sheet or sheets without sandwiching them, and a control device to control the discharging member switching device to switch the discharging member to the open condition before a tip end of the sheet being conveyed through the first conveying path reaches the discharging member.
In the above configuration, when a sheet is discharged to the stack tray, because the control device controls the discharging member switching device to switch the discharging member to the open condition before the conveyed sheet being conveyed toward the stack tray reaches the discharging member, a space downstream of the discharging member in the sheet conveying direction, that is, a space outside the apparatus, can be used as a part of the sheet conveying path. Therefore, a length of the stack tray or the distance from the entrance for the sheet to the stack tray to the nip portion of the discharging member can be shortened, and thereby the
Tsutsui Kazuya
Ushirogata Yoshiaki
Watanabe Tetsuji
Ellis Christopher P.
Mackey Patrick
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ricoh & Company, Ltd.
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