Sheet-material associating – Associating or disassociating – Sheet associating
Reexamination Certificate
2000-05-17
2002-04-23
Ellis, Christopher P. (Department: 3651)
Sheet-material associating
Associating or disassociating
Sheet associating
C270S058040, C270S058140, C271S003140, C271S003200, C271S262000, C271S265040
Reexamination Certificate
active
06375180
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a sheet finisher which receives sheets having an image formed on them in an image forming apparatus such as an electro-photographic copying machine, a printer, a facsimile apparatus, and a printing machine, and ejects them on to an output tray after applying a binding process by a binding means, to an image forming apparatus equipped with a sheet finisher, and to a sheet conveyance apparatus.
A sheet finisher which collates a plurality of sheets having an image formed on them ejected from an image forming apparatus and applies finish-processing by an finish-processing means such as a binding means are utilized.
The sheet finisher of this kind is functionally connected to an image forming apparatus such as a copying machine, a printer, and a facsimile apparatus, and is driven in accordance with the sequential operation of the copying or printing process.
Accordingly, for an image forming apparatus being capable of processing the image forming process at a high speed, it is required a sheet finisher being capable of high-speed processing which can perform the function in accordance with the process speed.
With respect to such a sheet finisher being capable of high-speed processing, it has already been disclosed in Tokkaisho 60-142359, Tokkaisho 60-158463, Tokkaisho 62-39169, Tokkaisho 62-288002, Tokkaisho 63-267667, Tokkaihei 2-276691 and Tokkouhei 5-41991.
In the above-described sheet finisher, sheets having an image formed on them conveyed out from the image forming apparatus mainframe are gripped and conveyed by a pair of conveyance rollers, and are successively stacked in an intermediate stacker while being collated, to be received as a bunch of sheets for one volume, and then they are subjected to an finish-processing by a stapler etc.; thus, the bunch of sheets subjected to the binding processing is then placed on an ejection belt provided at the bottom of the above-described intermediate stacker to be conveyed, and further it is gripped between an upper-and-lower pair of ejection rollers and ejected onto an output tray.
In Tokkaihei 9-235069, it is disclosed. to efficiently carry out the conveyance of sheets without stopping the sheet finisher during the interval for the transfer of operation from the finish-processing of the preceding bunch of sheets to the conveyance of the succeeding bunch of sheets, using a small-sized sheet finisher comprising a first sheet entry path for guiding a sheet conveyed out of an image forming apparatus, a second sheet entry path which diverges from said first sheet entry path at the upstream side and joins it at the downstream side, and a sheet conveyance means which makes the leading edge portions of the two sheets which have been conveyed through said first sheet entry path and second sheet entry path respectively get engaged with a conveyance roller pair to grip them in the overlapped state and then feeds them to the above-described intermediate stacker, wherein the first one of the succeeding sheets coming through the first sheet entry path is stopped by being engaged with the conveyance roller pair in still standing, the second sheet coming through the second sheet entry path is stopped to be on standby by being engaged with said conveyance roller pair in still standing in the state of being overlapped on the first sheet, and after the preceding bunch of sheets bound by a stapler is ejected from said intermediate stacker, the first one and the second one of the succeeding bunch of sheets are fed into said intermediate stacker at the same time as they are overlapped.
In order to convey two thick sheets in the state of being overlapped at the same time by a pair of conveyance rollers, a large conveying pressure is required, which makes the driving source large-sized too. If the initial sheet is conveyed out by this large conveying pressure and is made to strike against the outer circumferential surface of a conveyance roller located downstream, it produces problems such as roller contamination and the shortening of the roller life.
If the conveying pressure of the conveyance rollers is controlled to be varied, or a conveyance path is separately provided, the sheet finisher is made complex.
When the leading edge portions of the sheets conveyed by a conveyance means is made to strike against a stopper for truing up the leading edges and then the sheets are ejected into the above-described intermediate stacker, in order to improve the conveyance performance of the sheets, a wave-shaped deformation is formed in the direction parallel to the sheet conveying direction by conveyance rollers composed of a driving roller unit and a follower roller unit.
FIG. 17
shows a pair of conveyance rollers in a conventional sheet finisher; FIG.
17
(
a
) shows the front view, and FIG.
17
(
b
) shows the side cross-sectional view.
The rotary shaft RO of the aforesaid driving roller unit at the entrance of the intermediate stacker is supported in a manner capable of rotating by the apparatus mainframe, is connected to the driving source, and rotates for driving. To the rotary shaft R
0
, the driving roller members R
1
having a circumferential surface made of an elastic rubber, and flange rollers R
2
having an outer diameter larger than the outer diameter of the driving roller members R
1
made of a hard material are fixed.
The flange rollers R
2
carry it out to true up the leading edge portion of the sheets having been conveyed by the conveyance means by stopping them, and form a wave-shaped deformation in the sheets.
The follower rollers (pinch rollers) R
3
of the follower roller unit are urged by the roller pressing springs sp, to make pressing contact with the driving roller members R
1
.
When a thick sheet is conveyed by the driving roller members R
1
and the follower rollers R
3
in the state of pressing contact with them, the urging spring force by the roller pressing springs sp must be set to a strong level. However, if a thin sheet is conveyed by this strong urging spring force, the sheet P is damaged.
It is an object of this invention to improve the conveying capability for a thick sheet without damaging a thin sheet.
In the case where sheets ejected from an image forming apparatus are brought in a conveyance path of the conveyance means of a sheet finisher and conveyed by conveyance rollers, during the bind-processing of the preceding bunch of sheets, if two sheets composed of the first one and the second one of the succeeding sheets are conveyed by conveyance rollers at the same time as the two sheets are overlapped, the waiting time for the bind-processing is shortened, which improves the processing speed.
However, if the conveyance of two sheets being overlapped is carried out, the truing-up performance of the sheets by the aligning operation will become worse because the two sheets are made in close contact with each other by the static electricity etc. Further, when the side edges of thick sheets in the width direction is trued up by the aligning plates of the aligning means, if the side edges of the thick sheets in the width direction are strongly pressed by the aligning plates, the stepping motor for driving the aligning plates goes out of tuning by the resisting force of the thick sheets, which lowers the sheet truing-up performance after that.
In a conventional sheet finisher, driving of the stapler has been done at the same measured timer value for a thick sheet and a thin sheet through measuring the passing of the trailing edge by a sheet passage sensor. However, for thick sheets having different conveyance characteristics from a usual sheet, dispersion in the sheet passage time from the sheet passage detecting sensor to the conveyance rollers at the entrance of the intermediate stacker is produced depending on the kinds of sheet.
Especially, with respect to sheets having a smooth surface and a high stiffness, the above-described sheet conveyance time becomes greatly prolonged, and the leading edge portion in the progressing direction of the last sheet can not reach the stoppe
Kawano Minoru
Matsumoto Toshitaka
Ohtsuka Masaru
Okabe Hirohiko
Takahashi Tadahiro
Bierman, Muserlian and Lucas
Ellis Christopher P.
Konica Corporation
Mackey Patrick
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