Sheet-material associating – Associating or disassociating – Sheet associating
Reexamination Certificate
1997-12-29
2001-06-05
Ellis, Christopher P (Department: 3651)
Sheet-material associating
Associating or disassociating
Sheet associating
Reexamination Certificate
active
06241234
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
The present invention relates to a sheet processing apparatus which is employed in, for example, a copying machine, a laser beam printer, or the like. More specifically, it relates to a sheet processing apparatus which comprises a first means (hereinafter, “processing tray”) and a second means (hereinafter, “stacking tray”), for processing, for example, sorting or binding, the sheets discharged from the main assembly of an image forming apparatus.
In the past, a large number of inventions related to an apparatus constituted of a combination of a processing tray for stapling sheets as needed, and a stacking tray which receives and stores the sheets, have been submitted for a patent. One of such inventions is disclosed in U.S. Pat. No. 5,021,837.
FIG. 38
is a schematic vertical section of the apparatus depicted in the invention.
In this drawing, referential
figure 501 and 502
designate a processing tray and a stacking tray, respectively. Along the periphery of the processing tray, a stapler
503
for binding sheets, and a jogger
504
which shuttles in the direction perpendicular to the drawing to align sheets, are disposed.
With the provision of the above described structure, a set of sheets is discharged into the stacking tray
502
by a pair of sheet discharge rollers
505
and
506
after being aligned and stapled in the processing tray (stapling tray). The stacking tray
502
is enabled to alternately move frontward and backward (in the direction of sheet width) each time a stapled set of sheets is discharged into the stacking tray
502
, so that the stapled sets of sheets are sorted as they are discharged into the stacking tray
502
. It is also enabled to move vertically so that it aligns with the pair of discharge rollers
505
and
506
each time a stapled set of sheets is discharged. In other words, the stacking tray
502
gradually descends while alternately moving frontward and backward to sort the stapled sets of sheets.
Both the processing tray and the stacking tray
502
are slanted so that their downstream sides (left side of the drawing) are slightly higher. Therefore, the sheets are regulated, on the trailing edge side, by the trailing edge side wall
507
.
As an image forming operation continues, the number of sheets which are discharged into, and stacked in, the stack tray
502
becomes large. As a result, the sheets in the bottom portion of the stack are subjected to a large amount of pressure generated by the weight of the sheets stacked above, hence the contact pressure between the trailing edges of the sheets in the bottom portion of the stack, and the trailing end wall
507
, becomes very large. In the case of the apparatus based on the prior art, the stacking tray
502
is alternately moved frontward and backward in this condition, to sort the sheets. Therefore, the trailing edges of the sheets in the bottom portion of the stack are liable to sustain damages such as scratching, buckling, or the like anomalies, due to the friction between them and the trailing end wall
507
.
Further, in the case of a sheet processing apparatus based on the prior art, each sheet is discharged without being aligned with the preceding sheets, and therefore, a sheet processing apparatus based on the prior art could be improved greatly in terms of sheet alignment.
Further, in the case of a sheet processing apparatus based on the prior art, when a large number of sheets is discharged one by one into a stacking tray to be aligned as a set of sheets, the sheets which are already in the stack tray are liable to be disturbed, and therefore, means for holding them down from above, or the like, is necessary.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide a sheet processing apparatus comprising a means for desirably stacking sheets, in terms of alignment.
According to an aspect of the present invention, there is provided a sheet processing apparatus comprising first stacking means for stacking sheets discharged thereto; feeding means for feeding a set of sheets from said first stacking means; second stacking means for stacking the set of sheets fed by said feeding means; shifting means for shifting the sheets stacked on said first stacking means; control means for grouping the sheet in a set into a plurality of groups of sheets, and stacking, shifting and feeding the sheets, for each group, to said first stacking means, and for stacking the set of sheets on said second stacking means.
According to another aspect of the present invention, there is provided a sheet processing apparatus comprising first stacking means for stacking sheets discharged thereto; feeding means for feeding a set of sheets from said first stacking means; second stacking means for stacking the set of sheets fed by said feeding means; shifting means for shifting the sheets stacked on said first stacking means; control means for grouping the sheet in a set into a plurality of groups of sheets, and stacking, shifting and feeding the sheets, for each group, to said first stacking means, and for stacking the set of sheets on said second stacking means, said control means controlling said shifting means to stack a set of sheets and a set of sheets at offset positions on said stacking means.
According to a further aspect of the present invention, there is provided a sheet processing apparatus comprising first stacking means for stacking sheets discharged thereto; feeding means for feeding a set of sheets from said first stacking means; second stacking means for stacking the set of sheets fed by said feeding means; aligning means for aligning the sheets stacked on said first stacking means; control means for grouping the sheet in a set into a plurality of groups of sheets, and stacking, aligning and feeding the sheets, for each group, to said first stacking means, and for stacking the set of sheets on said second stacking means.
As described above, according to the present invention, a sheet set to be transferred from the first stacking means to the second stacking means is shifted, relative to the immediately preceding set of sheets, prior to its transfer onto the second stacking means, so that it does not need to be shifted after it is transferred into the second stacking means. Therefore, such sheet misalignment that occurs when a set of sheets is shifted in the second stacking means of a processing apparatus based on the prior art can be prevented, and also, the power source for driving the sheet processing means can be reduced in size.
Further, according to the present invention, when a set of a large number of sheets is transferred from the first stacking means to the second stacking means, the sheet set is divided into a number of sub-sets comprising a smaller number of sheets, and then, each sub-set of sheets is separately transferred into the second stacking means, and therefore, even a plurality of sets of a large number of sheets can be desirably stacked in terms of sheet alignment within in each set, and in terms of their displacement in the alternate direction, relative to the adjacent sets.
Further, according to the present invention, when a set of sheets constituted of a large number of sheets is processed, the set is divided into two or more sub-sets constituted of a relatively small number of sheets, and then, each sub-set of sheets is aligned independently from other sub-sets, and then discharged. Therefore, two or more sets of sheets can be stacked in a desirably staggered arrangement.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4424963 (1984-01-01), Bartholet et al.
patent: 4782363 (1988-11-01), Britt et al.
patent: 4926220 (1990-05-01), Matysek et al.
patent: 5021837 (1991-06-01), Uto et al.
patent: 5177548 (1993-01-01), Nakamura et al.
patent: 5201517 (1993-04-01), Stemmle
patent: 5
Hayashi Ken-ichi
Iwamoto Kazuyuki
Kawata Wataru
Saitoh Naho
Takehara Yoshifumi
Bower Kenneth W
Canon Kabushiki Kaisha
Ellis Christopher P
Fitzpatrick ,Cella, Harper & Scinto
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