Sheet feeding or delivering – Delivering – Multiple discharge
Reexamination Certificate
1999-03-15
2001-11-13
Ellis, Christopher P. (Department: 3651)
Sheet feeding or delivering
Delivering
Multiple discharge
C271S302000, C270S058110, C270S058120, C270S058130
Reexamination Certificate
active
06315288
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sheet post-processing apparatus and, more specifically, to a sheet post-processing apparatus which performs a predetermined post-processing operation such as a stapling operation on sheets successively fed therein at a predetermined interval from an image forming apparatus such as a copying machine.
2. Description of Related Art
It is often desired to perform a stapling operation or a punching operation on a relatively large number of sheets each bearing an image transferred thereon by an image forming apparatus such as a copying machine or a printer.
In such a case, a sheet post-processing apparatus or a so-called finisher is conveniently used which automatically performs predetermined post-processing operations including the stapling operation and the punching operation.
An exemplary construction of the finisher is schematically illustrated in FIG.
7
. The finisher
100
is detachably connected to a sheet discharging side of an image forming apparatus such as a copying machine, and includes an intermediate tray
101
which is capable of retaining therein a plurality of sheets P. Where a set of sheets successively discharged at a predetermined interval from the image forming apparatus is to be subjected to the stapling operation, the sheets P are once retained in the intermediate tray
101
.
An introduction section
102
including introduction rollers
102
a
and an introduction guide
102
b
is provided in association with an upper portion of the intermediate tray
101
. The sheets P discharged from the image forming apparatus are fed into the intermediate tray
101
via the introduction section
102
.
The intermediate tray
101
is provided with a sheet receiver
103
which is movable along the intermediate tray
101
. During the introduction of the sheets, the sheet receiver
103
is held on standby at a lower portion of the intermediate tray
101
. The sheets P are successively fed from an upper portion of the finisher
100
onto the sheet receiver
103
along the intermediate tray
101
through the introduction section
102
. Leading edges of the sheets P are supported by the sheet receiver
103
.
A stapler
104
for performing the stapling operation, for example, is provided adjacent a standby position of the sheet receiver
103
. The set of sheets P with their leading edges aligned (or registered) on the sheet receiver
103
is subjected to the stapling operation by the stapler
104
. The sheet set subjected to the stapling operation is transported upward toward the upper portion of the finisher
100
by the sheet receiver
103
, and discharged onto a sheet discharge tray
106
through sheet set discharging rollers
105
.
The time required before the intermediate tray
101
is ready for acceptance of the next set of sheets upon completion of the stapling operation performed on the sheet set currently retained in the intermediate tray
101
is longer than the time interval at which the sheets P are successively introduced into the intermediate tray.
Therefore, where sheets P are fed at the predetermined time interval from the image forming apparatus, the first sheet of the next sheet set should be held on standby in a sheet transportation path
107
for some time until the intermediate tray
101
is ready for the acceptance of the next sheet set upon completion of the stapling operation.
In one conventional apparatus (not shown), having a greater length than the ordinary transportation path
107
is provided so that the first sheet of the next sheet set is transported through the longer transportation path and the second sheet of the next sheet set is transported through the ordinary transportation path
107
for elimination of the standby time.
In another conventional apparatus (not shown), two intermediate trays are provided so that, while sheets retained in one of the intermediate trays are subjected to a predetermined post-processing operation, sheets of the next sheet set are transported into the other intermediate tray for elimination of the standby time.
In the case of the first prior art where the second transportation path is provided which is longer than the ordinary transportation path, however, the second transportation path is complicated because of its greater length. Therefore, the apparatus is liable to cause a sheet jam, and has a difficulty in maintenance operations such as a sheet jam recovering operation.
In the case of the second prior art where the two intermediate trays are provided, the apparatus has a correspondingly complicated construction and increased size.
On the other hand, where a positional relationship between the standby position of the sheet receiver
103
and the introduction section
102
is not proper with respect to the length of a sheet P, an event as shown in
FIG. 8
may occur. More specifically, a sheet P
2
slips into the rear side (the left side as seen in
FIG. 8
) of a sheet P
1
previously fed into the intermediate tray
101
.
Particularly, a sheet has a great warpage immediately after being heated for image fixation, so that the slip-in of the sheet is more liable to occur. If the slip-in of the sheet occurs, sheets to be discharged are arranged in a different collating order from an order in which the sheets have been fed from the copying machine.
The sheets transported into the intermediate tray
101
may have different lengths, as measured with respect to the transportation direction, depending upon the sheet type (A size, B size). Therefore, the conventional sheet post-processing apparatus is adapted to variably adjust the positions of the introduction section
102
and the sheet receiver
103
and the standby position of the stapler
104
in accordance with the sheet type. Thus, the positional relationship between the sheet receiver
103
and the introduction section
102
is optimized.
However, driver systems and the like are required for moving the introduction section
102
, the stapler
104
and the like in accordance with the sheet type. Therefore, the apparatus has a more complicated construction and a greater size.
SUMMARY OF THE INVENTION
It is a first object of the present invention to provide a sheet post-processing apparatus which has a simple and compact construction for reduction of a standby time between processing of one sheet set and processing of the next sheet set.
It is a second object of the present invention to provide a sheet post-processing apparatus which is capable of keeping the collating order of sheets with a simple and compact construction.
In accordance with a first aspect of the present invention, there is provided a sheet post-processing apparatus which comprises a sheet tray capable of retaining therein a plurality of sheets, and a transportation path for feeding a sheet to the sheet tray, the transportation path having a bypass path bypassing at least part of the transportation path. During a predetermined post-processing operation performed on one set of sheets previously supplied into the sheet tray, the first sheet of the next sheet set is once stopped within the transportation path or the bypass path, and the second sheet of the next sheet set is fed into the bypass path or the transportation path. Then, the first and second sheets of the next sheet set are fed into the sheet tray upon completion of the predetermined post-processing operation performed on the one set of sheets.
With this simple and compact construction, the standby time between the processing of the one sheet set and the processing of the nest sheet set can be reduced.
In accordance with a second aspect of the present invention, there is provided a sheet post-processing apparatus which comprises a sheet tray generally vertically disposed and capable of retaining therein a plurality of sheets, and is adapted to perform a predetermined sheet processing operation on a plurality of sheets with edges thereof registered adjacent a lower portion of the sheet tray (on a bottom of the tray or on a sheet receiver separately provided
Kondoh Kazuhisa
Matsuura Sadahiro
Okitsu Tadakazu
Okumura Keiji
Shimoyama Hiroshi
Ellis Christopher P.
Kyocera Mita Corporation
Mackey Patrick
Smith , Gambrell & Russell, LLP
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