Sheet feeding or delivering – Feeding – Separator and conveyor
Reexamination Certificate
1999-05-14
2001-10-23
Ellis, Christopher P. (Department: 3651)
Sheet feeding or delivering
Feeding
Separator and conveyor
C271S118000, C271S119000, C271S120000, C271S121000, C271S167000, C271S170000
Reexamination Certificate
active
06305682
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sheet supplying apparatus used with a recording apparatus such as a printer, a copying machine, a facsimile and the like.
2. Related Background Art
In conventional recording apparatuses such as printers, copying machines, facsimiles and the like, a thick sheet such as a post card, an envelope or a special sheet such as a plastic film are used as a sheet, as well as a plain sheet. The sheet is manually supplied or inserted one by one, or the sheets are automatically and successively supplied by means of a sheet supplying apparatus.
FIGS. 44 and 45
show an example of a conventional recording apparatus integrally incorporating a sheet supplying apparatus therein. In
FIGS. 44 and 45
, the recording apparatus comprises a sheet supplying apparatus
100
for separating and supplying sheets P one by one, and a recording portion
101
for recording an image on the supplied sheet P. The sheet supplying apparatus
100
has a pressure plate
103
shiftable with respect to a base (sheet stacking means)
102
, and a sheet stack P rested on the pressure plate
103
is urged against a sheet supply roller
105
and rollers
105
coaxial with the sheet supply roller by means of a pressure spring
104
. Further, a separation pawl
107
is located at a position corresponding to one of front corners of the sheet stack P. The separation pawl
107
is disposed at only one corner of the sheet stack.
Tip end of the sheets P stacked on the pressure plate abut against a sheet tip end abutment portion
102
a
provided at a lower end of the base
101
. As shown in
FIG. 45
, an abutment surface of the sheet tip end abutment portion
102
a
is inclined with respect a surface of the sheet stack P within an angular range of &bgr;° to &ggr;°. When a sheet having relatively small resiliency such as a thin sheet is used, as shown in
FIG. 45
, the sheets are supported in an inclined condition in such a manner that one front corner of the sheet stack P is regulated by the separation pawl
107
and the other front edge of the sheet stack (not regulated by the separation pawl) abuts against the sheet tip end abutment portion
102
a
. When the sheet supply roller
105
is contacted with the sheet stack P and is rotated, a conveying force acts on the sheet stack P.
On the other hand, since one front corner of the sheet stack P is regulated by the separation pawl
107
, only an uppermost sheet P overcome the resistance of the separation pawl
107
to ride over the latter, thereby separating the uppermost sheet from the other sheets. The separated sheet is supplied to the recording portion
101
.
When a sheet having relatively great resiliency such as an envelope and a post card is used, since the sheet is not flexed in the vicinity of the separation pawl
107
sufficient to be separated by the separating action of the separation pawl
107
, it is difficult to separate the uppermost sheet from the other sheets by the separation pawl
107
. Thus, regarding the sheet P having relatively great resiliency, the separation pawl
107
(located at one front corner of the sheet stack) is spaced apart from the sheet stack, and the sheet is separated in the following manner. The sheets having relatively great resiliency are prevented from advancing toward a downstream side due to friction between the tip end of the sheet stack and the sheet tip end abutment portion
102
a
when the tip end of the sheet stack abut against the sheet tip end abutment portion
102
a
(regulated condition). In order to release such a regulated condition, it is necessary to overcome the resiliency of the sheet to flex the sheet and to provide a conveying force sufficient to feed the sheet P toward the downstream side in opposition to the friction between the tip end of the sheet stack P and the sheet tip end abutment portion
102
a.
When the uppermost sheet directly contacted with the sheet supply roller
105
is subjected to the conveying force from the sheet supply roller
105
, the conveying force of the sheet supply roller
105
indirectly acts on the other sheets (other than the uppermost sheet) due to friction between the sheets. In consideration of this fact, the inclination angle &bgr;° to &ggr;° (with respect to the surface of the sheet stack P) of the abutment surface of the sheet tip end abutment portion
102
a
is selected so that only the uppermost sheet P directly subjected to the conveying force of the sheet supply roller
105
is supplied and the other sheets P are regulated (i.e., not supplied). With this arrangement, the sheets having relatively great resiliency can be separated and supplied one by one.
Further, in such a recording apparatus, it is requested that the sheet can be supplied or inserted one by one manually. To satisfy this requirement, the inclination angle of the pressure plate
103
and the inclination angle &bgr;° to &ggr;° (with respect to the surface of the sheet stack P) of the abutment surface of the sheet tip end abutment portion
102
a
are selected so that the sheet P can be inserted up to the sheet tip end abutment portion
102
a
without interference and can reach a convey roller (not shown) through the sheet tip end abutment portion
102
a.
As mentioned above, the inclination angle &bgr;° to &ggr;° (with respect to the surface of the sheet stack P) of the abutment surface of the sheet tip end abutment portion
102
a
is selected in a relatively narrow angular range so that both the sheets P having relatively small resiliency and the sheets P having relatively great resiliency can be held, separated and supplied and at the same time the manual sheet insertion is permitted. However, in the above-mentioned conventional sheet supplying apparatus has the following drawbacks:
(1) Since only one front corner of the sheet stack P is regulated by the separation pawl
107
and the other front edge of the sheet stack is supported by the sheet tip end abutment portion
102
a
, when the sheets P having relatively small resiliency are used, the other front corner of the sheet stack (not regulated by the separation pawl
107
) is often protruded toward the downstream side, thereby causing the skew-feed of sheet in the recording portion
101
.
(
2
) When the sheets P are stacked on the pressure plate
103
for a long time, the other front corner of the sheet stack (not regulated by the separation pawl
107
) is gradually protruded toward the downstream side and the regulated condition of the front corner of the sheet stack P regulated by the separation pawl
107
becomes unstable. In such a condition, if the sheet supplying operation is performed, poor sheet separation is generated, thereby causing the double-feed of sheets.
(3) During the stacking operation of the sheets P on the pressure plate
103
, after the tip end of the sheet stack P abut against the sheet tip end abutment portion
102
a
, when the sheet stack P is slid laterally until a side edge of the sheet stack is contacted with a side reference surface
102
b
for positioning the side edge of the sheet stack P, since the tip end of the sheet stack is shifted along the sheet tip end abutment portion
102
a
, the tip end of the sheet stack is gradually slid down from the sheet tip end abutment portion
102
a
toward the downstream side. As a result, when the side edge of the sheet stack is contacted with the side reference surface
102
b
, the front corner of the sheet stack P regulated by the separation pawl
107
is shifted toward the downstream side of the separation pawl
107
, with the result that the front corner of the sheet stack is not regulated by the separation pawl
107
. In this condition, when the sheet supplying operation is performed, a plurality of sheet P not regulated by the separation pawl
107
are supplied at once.
(4) In order to amend the poor sheet tip end holding ability described in the above items (1) and (2), if the inclination angle &bgr;° to &ggr;° (with respect to the surface of the sheet stack P) of the sheet tip end abutment portion
10
Ming Tan At
Saikawa Satoshi
Saito Hiroyuki
Yanagi Haruyuki
Butler Michael E.
Canon Kabushiki Kaisha
Ellis Christopher P.
Fitzpatrick ,Cella, Harper & Scinto
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