Sheet feeding or delivering – Feeding – Separators
Reexamination Certificate
1999-12-17
2001-11-20
Skaggs, H. Grant (Department: 3651)
Sheet feeding or delivering
Feeding
Separators
C271S124000
Reexamination Certificate
active
06318716
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a sheet separating apparatus provided in an image forming apparatus such as a copying machine, a printer or a facsimile apparatus for separating and feeding out recording sheets and originals one by one.
2. Related Background Art
An image forming apparatus has heretofore been equipped with a sheet separating apparatus for separating and supplying recording sheets and originals one by one to an image forming portion and an original reading portion. In this sheet separating apparatus, use is made of various separating systems such as a separating pawl (claw), a separating pad and a reversely rotating roller in conformity with the separating property, cost, etc.
FIG. 5
of the accompanying drawings shows an example of a sheet separating apparatus adopting a separating system using a separating pad according to the prior art. This will hereinafter be schematically described.
The reference numeral
50
designates a sheet feeding roller which is rotated in the direction of arrow E to thereby feed out recording sheets or originals (hereinafter referred to as sheets) P stacked (piled) on a sheet feeding tray
51
and a pressure plate
52
. The pressure plate
52
is supported for pivotal movement in the directions of arrow A-B about a shaft
53
, and biases the leading end side of the piled sheets P toward the sheet feeding roller
50
by a spring member, not shown and brings the sheets into pressure contact with the sheet feeding roller
50
. The pressure plate
52
is provided with a friction pad
52
a
for preventing the sheets from being fed out as a bundle when the number of the piled sheets has become small.
A separating pad
54
for separating the sheets is provided on the downstream side of the pressure plate
52
with respect to the sheet feeding direction. This separating pad
54
is held on a pad holder
56
supported pivotally in the directions of arrow C-D about a shaft
55
, and is brought into pressure contact with the sheet feeding roller
50
by a separating spring
57
.
According to this construction, the sheets brought into pressure contact by the pressure plate
52
are fed out toward the separating pad
54
by the sheet feeding roller
50
being rotated in the direction of arrow E. These sheets thus fed out are separated one by one between the sheet feeding roller
50
and the separating pad
54
and fed toward the downstream side. To reliably separate the sheets in this case, the coefficient of friction between the surface of the separating pad
54
and the surface of the sheet feeding roller
50
must be higher than the coefficient of friction between the sheets, and need generally that &mgr; is equal to 1 or greater with the kind of the sheets used and environmental conditions such as temperature and humidity taken into account.
The sheet separating apparatus adopting the above-described separating pad system according to the prior art, however, has suffered from the following problem.
As described above, the coefficient of friction between the sheet feeding roller
50
and the separating pad
54
is sufficiently high for the separation of the sheets. Therefore, if the sheet feeding roller
50
is rotated with no sheet inserted in the nip portion (the portion of pressure contact) between the sheet feeding roller
50
and the separating pad
54
, i.e., with the sheet feeding roller
50
and the separating pad
54
directly brought into pressure contact with each other as shown in
FIG. 5
, a minute slip stick phenomenon may occur between the sheet feeding roller
50
and the separating pad
54
and the separating pad may be vibrated to thereby cause unpleasant noise (chattering sound).
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-noted problem and has as its object to provide a sheet separating apparatus which can prevent vibration causing the unpleasant noise of a separating pad by a simple construction without adversely affecting the separating performance.
The sheet separating apparatus of the present invention is characterized by:
sheet feeding means for feeding sheets;
a separating pad for separating the sheets between it and said sheet feeding means;
a pad holding member for holding said separating pad;
biasing means for biasing said pad holding member to thereby bring said separating pad into pressure contact with said sheet feeding means;
supporting means for supporting said pad holding member on a frame pivotably and movably in a sheet feeding direction; and
an abutting surface against which said pad holding member abuts when said pad holding member moves to a downstream side with respect to the sheet feeding direction.
REFERENCES:
patent: 466171 A2 (1992-01-01), None
patent: 0321230 (1989-12-01), None
patent: 403061235A (1991-03-01), None
patent: 403102032A (1991-04-01), None
patent: 403088645 (1991-04-01), None
patent: 405043077A (1993-02-01), None
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Skaggs H. Grant
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