Sheet feeding or delivering – Feeding – Separator and conveyor
Utility Patent
1999-03-15
2001-01-02
Skaggs, H. Grant (Department: 3651)
Sheet feeding or delivering
Feeding
Separator and conveyor
C271S122000, C271S125000, C271S242000
Utility Patent
active
06168146
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a sheet feeding apparatus for feeding and conveying sheets (paper leaves such as originals, transfer paper, photosensitive paper, electrostatic recording paper, thermosensitive paper, printing paper, OHP sheets, envelopes and postcards) such as cards and thin paper leaves piled in various sheet-using apparatuses such as image forming apparatuses including rotary type cameras, facsimile apparatuses, printing machines, copying machines, printers, word processors, etc. and other apparatuses such as automatic original feeding apparatuses, punching machines and paper binding machines one by one to a sheet processing portion such as an image forming portion, an exposure portion and a processing portion.
2. Related Background Art
As one of the sheet separating mechanisms of sheet feeding apparatus for separating and conveying piled sheets one by one, there is known a mechanism using a pair of comb-toothed rollers.
This mechanism is such that two comb-toothed rollers formed with comb-tooth-like grooves in the outer peripheral portion thereof are disposed in opposed relationship with each other substantially in parallelism to each other with the concave surfaces and convex surfaces of their grooves axially overlapping each other in non-contact with each other, and one of the two rollers is used as a feeding roller and the frictional force thereof with respect to a sheet is made great and the other roller is used as a separating roller and the frictional force thereof with respect to the sheet is made smaller than that of the feeding roller. The feeding roller is rotated in a forward feeding direction and the separating roller is rotated in a reverse feeding direction, and the sheet is fed to the nip portion between this pair of rollers. Thereby, even if a plurality of sheets are fed in overlapping relationship with one another, only the sheet which is in contact with the feeding roller is passed through the nip portion by the feeding force of the feeding roller rotated in the forward feeding direction, irrespective of the separating roller rotated in the reverse feeding direction, and the other sheets are reversely conveyed by the separating roller rotated in the reverse feeding direction and is prevented from coming into or being passed through the nip portion, whereby only that sheet which is in contact with the feeding roller is separated and conveyed.
There is also known a mechanism in which when sheets are separated and conveyed one by one, a movable guide plate provided at one side or both sides of the sheet to prevent skew feeding is moved and the side portion of a skew-fed sheet is pushed against the guide plate to thereby correct skew feeding, or a mechanism in which the skew feeding of a sheet being fed is detected by the use of a sensor and as required, a conveying roller is rotatively driven by an amount corresponding to the skew feeding to thereby forcibly effect correction.
FIG. 13A
schematically shows the construction of a sheet feeding apparatus using a pair of comb-toothed rollers as a sheet separating mechanism.
sheets
200
are piled and set in a predetermined manner on a sheet supply tray
1
. This sheet supply tray
1
is vertically controlled to a sheet supply position indicated by solid line and a standby position indicated by dots-and-dash line.
An upper guide plate
2
and a lower guide plate
3
together constitute a sheet conveying path. The sheet supply tray side of the lower guide plate
3
is downwardly bent forwardly of the fore end of the sheet supply tray
1
to provide a sheet leading end ramming plate portion
3
a
for uniformizing the position of the leading end surface of the sheets piled on the sheet supply tray
1
.
A sheet feeding roller
4
picks up and feeds the sheets
200
piled and set on the sheet supply tray
1
.
A pair of feeding roller and separating roller
5
and
6
are disposed downstream of the sheet feeding roller
4
with respect to the direction of sheet conveyance. The feeding roller
5
is an upper roller and the separating roller
6
is a lower roller.
The feeding roller
5
and the separating roller
6
, as shown in the perspective view of
FIG. 13B
, are such that comb-toothed rollers formed with comb-tooth-like grooves in the outer peripheral portions thereof are disposed in opposed relationship with each other substantially in parallelism to each other with the concave surfaces and convex surfaces of the grooves thereof axially overlapping each other in non-contact with each other. The frictional force of the feeding roller
5
with respect to the sheet is made greater than the frictional force of the separating roller
6
with respect to the sheet.
Registration rollers
16
and conveying rollers
17
are successively disposed downstream of the pair of feeding roller and separating roller
5
and
6
with respect to the direction of sheet conveyance.
The sheet feeding roller
4
receives the transmission of motive power from a first motor M
1
through a pulley
12
, a belt
11
, a two-step pulley
10
, a belt
8
and a pulley
4
a,
and is rotatively driven in the clockwise direction of arrow which is a forward feeding direction.
Of the feeding roller
5
and the separating roller
6
, the feeding roller
5
receives the transmission of motive power from the first motor M
1
through the pulley
12
, the belt
11
, the two-step pulley
10
, a belt
9
and a pulley
5
a,
and is rotatively driven in the clockwise direction of arrow A which is the forward feeding direction.
Also, the separating roller
6
receives the transmission of motive power from a second motor M
2
through a pulley
13
, a belt
7
and a pulley
6
a,
and is rotatively driven at the nip portion with the feeding roller
5
in the clockwise direction of arrow B which is a reverse feeding direction.
Of the feeding roller
5
and the separating roller
6
, the feeding roller
5
is disposed on a movable chassis
21
pivotally movable about the support shaft of the two-step pulley
10
. The reference numeral
20
designates a shaft provided on the upper side of the movable chassis
21
, and the reference character
20
a
denotes a cam follower provided on one end side of this shaft
20
. The reference numeral
19
designates an eccentric cam, and the movable chassis
21
is counter-clockwisely biased about the support shaft of the two-step pulley
10
by a biasing spring member, not shown, so that the cam follower
20
a
may be normally in contact with the lower surface portion of the eccentric cam
19
. The reference numeral
27
denotes an adjusting knob for rotatively operating the eccentric cam
19
.
The above-described adjusting knob
27
, eccentric cam
19
, can follower
20
a,
shaft
20
, movable chassis
21
, etc. together constitute a mechanism for changing the distance between the shafts of the feeding roller
5
and the separating roller
6
.
That is, by the adjusting knob
27
being turned, the cam
19
is rotated and the motion of the cam is transmitted to the feeding roller
5
through the cam follower
20
a,
the shaft
20
and the movable chassis
21
, and the vertical position of the feeding roller
5
is displaced, and the distance between the shafts of the feeding roller
5
and the separating roller
6
can be changed more or less to thereby adjust the amount of entry or the amount of gap of the feeding roller
5
relative to the separating roller
6
in accordance with the thickness of the sheet.
Thus, during non-sheet feeding, the sheet supply tray
1
is lowered to its standby position indicated by dots-and-dash line, and is downwardly spaced apart from the sheet feeding roller
4
. In this state, the sheets
200
are piled and set on the sheet supply tray
1
. The sheets
200
are sufficiently inserted until the leading end thereof strikes against the ramming plate portion
3
a,
whereby the position of the leading end surface of the sheets piled on the sheet supply tray
1
is uniformized.
On the basis of a sheet feed starting signal, the sheet supply
Komuro Hiroshi
Okitsu Katsuhiko
Sashida Minoru
Sugiyama Kazuhide
Canon Denshi Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Skaggs H. Grant
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