Sheet feeding or delivering – Feeding – Separator and conveyor
Reexamination Certificate
2000-09-27
2003-08-26
Bollinger, David H. (Department: 3658)
Sheet feeding or delivering
Feeding
Separator and conveyor
C271S010130, C271S122000, C271S127000, C271S160000
Reexamination Certificate
active
06609707
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to feeding apparatuses and, more particularly, to a feeding apparatus for use in image forming apparatuses and image reading apparatuses such as a copying machine and a printer or the like.
2. Related Background Art
FIG. 13
is a schematic sectional view of a manual sheet feeding apparatus capable of continuous sheet feeding using a retard separation system according to a conventional art.
Referring to
FIG. 13
, reference numeral
102
denotes a pick-up roller driven and controlled by a conveyor clutch
108
for rotation and suspension of rotation, so as to feed a sheet S carried on a sheet feeding tray
101
one by one. After the sheet S is transported to a separation position between a separating roller
104
and a sheet feeding roller
103
, a pick-up solenoid
106
causes the pick-up roller
102
to be detached from the sheet S.
This detachment is necessary to ensure that, in the case where a plurality of sheets are transported to a separation position at the time of a pick-up operation by the pick-up roller
102
(hereinafter, such a situation will be referred to as double feeding), the double feeding can be certainly prevented by not hindering any reverse force of the sheet which is double fed at the time of separation by the separating roller
104
.
Moreover, in a non-active state of the main system, the pick-up roller
102
is also caused by the pick-up solenoid
106
to be detached from the sheet to ensure that the pick-up roller
102
does not hinder a setting operation performed by a user.
Additionally, a shutter
110
activated only when a sheet feeding apparatus is in a non-active state is provided to ensure that a user's inappropriate operation performed in setting a bundle of sheets does not cause the bundle of sheets to advance to the separation position and to provide the user with a feedback pressure so that the inappropriate setting operation does not cause a malfunction of the pick-up operation. The shutter solenoid
107
causes the shutter
110
to operate properly.
As described above, the manual sheet feeding apparatus according to the conventional art that employs the retard separating system requires the pickup roller
102
for feeding the sheet S one by one from the bundle of sheets. Further, a mechanism for detaching the pick-up roller
102
from the sheet, implemented by the solenoid
106
, is necessary not to hinder any setting operation.
The shutter
110
, which prevents the user's inappropriate operation, and the shutter solenoid
107
for controlling the shutter
110
are necessary.
Consequently, the requirement for space for housing the system may grow significantly, the construction may become complex and the cost of manufacturing may become relatively expensive.
Another disadvantage is that, in the construction described above, the driving and control of the pick-up roller
102
for rotation and suspension of rotation, as well as the control of the pick-up roller
102
for elevation and lowering require the conveyor clutch
108
and the shutter solenoid
106
. Therefore, the likelihood that an error is produced in actuating the conveyor clutch
108
and the shutter solenoid is relatively great. As a result, the operation of the sheet feeding apparatus may be improperly timed, thereby causing double feeding or paper jam.
For example, the detachment of the pick-up roller
102
should be properly timed to occur when the leading edge of the sheet S reaches a nip between the sheet feeding roller
103
and the separating roller
104
. Otherwise, delayed feed paper jam occurs. The detachment of the pick-up roller
102
should also occur before the leading edge of the sheet reaches a feed roller pair
105
provided downstream. Otherwise, the pick-up roller
102
loses the chance to force the sheet backward, thus causing double feeding. Thus, double feeding or paper jam is caused.
Moreover, timing requirement for the control of the conveyor clutch
108
and the solenoid
106
is so great as to make the control procedure extremely complex.
SUMMARY OF THE INVENTION
The present invention has been developed in view of the disadvantages described above and has an object of providing a sheet feeding apparatus and an image forming apparatus provided with the same, in which the cost and size are reduced by simplifying the construction, and in which proper timing is maintained and the stable sheet feeding and separation are performed. A typical components of the apparatus include displaceable sheet supporting means for supporting sheets; a feeding rotation body for feeding the sheet forward by contacting the sheet supported by the displaceable sheet supporting means and rotating in a direction of transportation of the sheet; and a separating roller pressed against the feeding rotation body and rotated in a direction to force the sheet fed by the feeding rotation body backward so as to separate the sheet. The sheet supporting means, the feeding rotation body and the separating rotation body are disposed such that an angle &thgr; satisfies a condition 15×(&pgr;/180) rad (=15°)≦&thgr;≦50×(&pgr;/&pgr;180) rad (=50°), where &thgr; denotes an angle between a line tangent to the feeding rotation body when the sheet supporting means is displaced to cause the topmost sheet supported by the sheet supporting means comes into contact with the feeding rotation body, and a nip line of a nip where the feeding rotation body and the separating rotation body are pressed against each other.
REFERENCES:
patent: 5016866 (1991-05-01), Takahashi
patent: 5582399 (1996-12-01), Sugiura
patent: 5725208 (1998-03-01), Miyauchi
patent: 6045220 (2000-04-01), Kiyohara et al.
patent: 6059281 (2000-05-01), Nakamura et al.
patent: 6260840 (2001-07-01), Suga et al.
patent: 0082746 (1981-07-01), None
patent: 0196422 (1988-08-01), None
Bollinger David H.
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
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