Electrophotography – Document handling – Copy
Reexamination Certificate
1999-03-09
2001-06-26
Grainger, Quana M. (Department: 2852)
Electrophotography
Document handling
Copy
C270S058070
Reexamination Certificate
active
06253057
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sheet processing apparatus, and more particularly, it relates to a sheet processing apparatus used with an image forming apparatus such as a copying machine and having a sheet punching device for perforating a sheet to be discharged, and an image forming apparatus having such a sheet processing apparatus.
2. Related Background Art
Conventionally, in some cases, a puncher for forming perforations in an end portion of a sheet (outputted from an image forming apparatus such as a printer, a copying machine and the like) to permit the sheets to be filed in a binder as a sheet bundle has additionally been used with a sheet processing apparatus.
Such a puncher serves to collectively form perforations in a sheet bundle including discharged sheets on which images were formed. In such a puncher, since the sheet bundle must be set in the puncher manually, workability is worsened. Further, if the sheet bundle includes a large number of sheets, a punch and a die of the puncher are subjected to great load, with the result that a greater force is required for perforating the sheet bundle and/or the punch and die are worn to generate poor punching and burrs in the perforations. To avoid this, if the sheet bundle includes a large number of sheets, the sheet bundle must be divided into sheet bundles each including a predetermined number of sheets or less and the divided sheet bundles must be perforated respectively, which results in further reduction of workability.
To cope with this, there has been proposed a sheet processing apparatus in which a puncher is provided in a sheet convey path and sheets stacked (as a sheet bundle) on a process tray in the apparatus are aligned and perforated collectively. With this arrangement, a conventional procedure for setting the sheet bundle in the puncher can be omitted, thereby enhancing the sheet processing ability.
However, in this apparatus, since the sheet bundle stacked on the process tray is perforated collectively, a next sheet cannot be conveyed while the sheet bundle is being perforated, with the result that it is difficult to increase a sheet conveying and processing speed of the image forming apparatus. Further, since the sheet bundle is perforated collectively, for every predetermined number of sheets, the perforating operation must be performed.
To solve this problem, there has been proposed a sheet processing apparatus in which a puncher comprising a rotatable punch and a rotatable die is provided in a sheet convey path, and a sheet conveying speed and a rotational speed of the puncher are synchronized. An example of such a puncher is shown in
FIGS. 10A and 10B
. In
FIGS. 10A and 10B
, a sheet (not shown) is conveyed through a sheet guide
13
a
of a puncher
13
from the above, and a rear end portion of the sheet is perforated by a punch
14
rotated in a direction shown by the arrow A and a die
15
rotated in a direction shown by the arrow B. Punch debris (punched pieces) PW produced in the punching operation is collected in a die cover
15
a
integrally formed with the die
15
. As shown by the arrow a, the punched pieces PW are discharged into a puncher frame
25
through an opening
15
e
of the die cover
15
a
and are collected in a punch dust box (not shown) through a dust dropping hole
16
of the puncher frame
25
. When the box is filled with the punched pieces PW, the punch dust box is removed from the image forming apparatus and the punched pieces PW are discarded.
With an arrangement as mentioned above, it is possible to perforate each sheet without stopping the conveyance of the sheet.
However, although a large amount of punched pieces PW discharged from the die cover
15
a
are dropped through the dust dropping hole
16
, some of punched pieces PW are gradually accumulated in an area where the hole
16
does not exist, thereby sometimes closing the dust dropping hole
16
.
Further, when the die cover
15
a
containing the punched pieces PW therein continues to rotate, the die cover
15
a
is electrically charged, with the result that the punched pieces PW are adhered to inner and outer peripheral surfaces of the die cover
15
a
to accumulate the punched pieces PW within the die cover
15
a
and the punched pieces PW adhered to the outer surface of the die cover
15
a
are scattered into the sheet guide
13
a.
Further, when the sheet is punched by the punch die
15
, the punched pieces PW may not be advanced inwardly of the die but are scattered outwardly of the die toward the sheet guide.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a sheet processing apparatus having a puncher, in which punched pieces discharged from a die cover into a punch dust box can be discharged from a dust dropping hole smoothly thereby to prevent the punched pieces from being accumulated within a puncher frame, and an image forming apparatus having such a sheet processing apparatus.
A sheet conveyed to the puncher through a sheet convey path is perforated by a punch and a die disposed within the puncher frame, and the punched pieces produced during the perforating operation and trapped within the die cover are discharged to a dust guide means through an opening of the die cover as the die cover is rotated and then are discharged out of the puncher frame while being guided by a partition plate and an inclined plate of the dust guide means. Thus, the punched pieces can be discharged from the puncher frame without inclining the puncher frame, thereby preventing the punched pieces from being accumulated within the puncher frame or from closing the dust dropping hole.
Further, by forming the die cover from antistatic material, the punched pieces can be prevented from being adhered to the die cover, thereby preventing the punched pieces from being accumulated within the die cover and from scattering into the sheet guide due to adhesion of the punched pieces to the outer surface of the die cover.
Further, the produced punched pieces are collected in the die cover and are discharged from the opening along a tapered portion of the die cover. Since the punched pieces in the die cover are discharged positively, the punched pieces can be prevented from being accumulated within the die cover.
Further, by providing a boss on the punch, during the punching operation, the punched pieces are pushed inwardly of the die by the boss, thereby preventing the punched pieces from scattering outwardly of the die.
Further, when a punch job is continuously effected for the sheets, under the action of a centrifugal force generated by the rotation of the die, the punched pieces may be adhered to the inner surface of the die. However, after the punch job was finished or immediately before the punch job is started, by rotating the die through a predetermined angle at a low speed and then rotating it in a reverse direction through a predetermined angle, the punched pieces can be dropped within the die cover.
REFERENCES:
patent: 5290020 (1994-03-01), Matsui et al.
patent: 5746162 (1998-05-01), Hosoi et al.
patent: 56-33239 (1981-04-01), None
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Grainger Quana M.
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