Sheet feeding or delivering – Feeding – Separators
Reexamination Certificate
2000-09-28
2003-03-25
Walsh, Donald P. (Department: 3651)
Sheet feeding or delivering
Feeding
Separators
C271S126000, C271S127000, C271S037000
Reexamination Certificate
active
06536759
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a sheet feeding apparatus in an image forming apparatus such as a photocopier, a printer, or the like or in an image reading apparatus for reading image information formed on sheets.
2. Description of Related Art
FIG. 14
shows a schematic cross section of a sheet feeding apparatus capable of successively feeding sheets in use of an intermediate plate
100
, a feeding roller
101
, and a separating roller
102
and a Schematic cross section of a separation guide
103
. The separation guide
103
formed in having a uniform cross section in a sheet width direction near the separating roller
102
is provided at a certain distance away from a separation nipping portion as a sheet nipping portion at which the feeding roller
101
and the separating roller
102
rotating with a prescribed torque in a direction returning the sheet with the feeding roller
101
. A hitting plate
103
extending approximately vertically with respect to the intermediate plate
100
so that the sheet front end stacked on the intermediate plate
100
hits to the plate
103
while the intermediate plate
100
is disengaged is disposed on an upstream side in the sheet feeding direction of the separation guide
103
with respect to the separation nipping portion.
The separation guide
103
has an opening
103
c
to project the separating roller
102
from a guide surface
103
b
to sandwich the sheet with the feeding roller
101
at prescribe pressure. A pulling roller
104
is formed on a downstream side in the sheet conveyance direction of the feeding roller
101
, thereby further feeding in the downstream direction the sheet fed from the feeding roller
101
.
In feeding operation, where the intermediate plate
100
moves in a direction contacting with the feeding roller
101
, the sheets stacked on the intermediate plate
100
come in contact with the feeding roller
101
, thereby conveying the front ends of the sheets sent by the feeding roller
101
to the separation nipping portion along the separation guide
103
.
The sheets are conveyed toward the pulling roller
104
, and when the sheets other than the topmost sheet are sent to the separation nipping portion, the separating roller
102
rotating with a prescribed returning torque reverses the sheets in the direction of the intermediate plate
100
to prevent the plural sheets from being fed at a time. Where a single sheet is nipped at the separation nipping portion, the separating roller
102
rotates in the conveyance direction according to the rotation force of the feeding roller
101
.
In the sheet feeding apparatus thus structured, however, if sheets having a high rigidity and a large frictional coefficient between the sheets are fed, sheets next to the topmost and below may enter in the nipping portion when the sheets enter in the separation nipping portion, and the sheet front end hits the outer peripheral surface of the separating roller in the center direction (or normal direction) of the separating roller, giving the separating roller
102
force in a direction of arrow F, thereby pushing down the separating roller
102
to isolate from the feeding roller
101
.
Where the separating roller
102
separates from the feeding roller
101
and where the front ends of the sheets next to the topmost and below hit the separating roller
102
, the nipping force for nipping the sheets with the feeding roller
101
and the separating roller
102
, or separation pressure that the separating roller
102
contacts in pressure with the feeding roller
101
is greatly reduced. Where the separation pressure is reduced, the separating roller
102
cannot rotate in following the rotation of the feeding roller
101
and the conveyance of the topmost sheet and may rotate in the returning direction. The feeding roller
101
thereby cannot feed the sheet further, so that the sheets cannot be conveyed to pulling roller
104
.
Where the sheets are conveyed from the separation nipping portion, if the sheet has a high rigidity, the sheets are conveyed in a state that the separating roller
102
are pushed down in a direction separating from the feeding roller
101
. That is, the sheets are conveyed in the direction as sinking down in a direction of arrow F. The separation guide
103
has the opening
103
c
only for the roller width of the separating roller
102
, so that the sunken sheet front end may hit an end
103
d
of the opening
103
c
of the separation guide
103
and may cause paper jamming.
This invention is conceived to solve the above problems. It is an object of the invention to provide a sheet feeding apparatus capable of stably feeding sheets without any conveyance failure even where sheets having a high rigidity or having a large frictional coefficient between the sheets are conveyed.
SUMMARY OF THE INVENTION
A representative structure of the invention to accomplish the above objects includes sheet supporting means movable for supporting a sheet or sheets; a feeding rotary member in contact with the sheet supported by the sheet supporting means to feed out the sheet upon rotation of the feeding rotary member; and a separating rotary member forming a contact portion in contact with the feeding rotary member and being rotatable in a direction returning the sheet to separate the sheet fed out of the feeding rotary member, wherein the sheet supporting means, the feeding rotary member, and the separating rotary member are so disposed that an angle formed on a side facing to the feeding rotary member by intersecting a tangential line of the feeding rotary member at a contacting position between the feeding rotary member and the sheet with a tangential line at the contact portion is an obtuse angle, and further includes a conveyance guiding means disposed on a side of the separating rotary member with respect to the contact portion for guiding the sheet fed to the feeding rotary member to the contact portion, the conveyance guiding means having a projection guiding means for projecting the contact portion on an upstream side in the sheet conveyance direction of the contact portion more toward the side of the feeding rotary member than a guide surface of the contact portion.
REFERENCES:
patent: 4852868 (1989-08-01), Fukui et al.
patent: 5350168 (1994-09-01), Sheridan
patent: 5655762 (1997-08-01), Yergenson
patent: 5927706 (1999-07-01), HIroi et al.
patent: 6129347 (2000-10-01), Brooks et al.
patent: 6260840 (2001-07-01), Suga et al.
Canon Kabushiki Kaisha
Deuble Mark A.
Fitzpatrick ,Cella, Harper & Scinto
Walsh Donald P.
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