Sheet feeding or delivering – Feeding – Separators
Reexamination Certificate
1999-11-02
2002-05-07
Bollinger, David H. (Department: 3651)
Sheet feeding or delivering
Feeding
Separators
C271S121000, C271S167000
Reexamination Certificate
active
06382621
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a paper feeder for feeding, one by one, sheets stacked together which is for use in an image forming apparatus or the like for forming images on sheets.
2. Description of the Related Art
A conventional paper feeder for use in image forming apparatuses adopts a slope surface separation system in which separation of sheets is effected by utilizing a slope surface. In the slope surface separation type paper feeder, a slope surface is provided at the forward end of the stacked sheets, and a paper feeding roller contacts the uppermost sheet to deliver it, the delivered sheet abutting the slope surface, whereby the sheets are separated from each other.
Usually, this slope surface separation type paper feeder is used when delivering sheets stacked horizontally. However, by inclining the sheet stacking surface, the installation area of the image forming apparatus can be reduced, and the apparatus size can be reduced, so that it is to be considered appropriate to apply the slope surface separation system to this inclined structure.
An example in which the slope surface separation system is applied to a paper feeder in which the sheet stacking surface is inclined will be described with reference to
FIGS. 14 and 15
. In the drawings, numeral
101
indicates a sheet stacking surface on which sheets S are to be placed, and numeral
102
indicates a paper feeding roller integrally holding a gear (not shown). Numeral
103
indicates an idler gear A in mesh with the gear of the paper feeding roller, numeral
104
indicates an idler gear B in mesh with the idler gear A
103
, numeral
105
indicates a drive shaft, and numeral
106
indicates a drive gear fastened to the drive shaft
105
and in mesh with the idler gear B. Numeral
107
indicates a paper feeding roller arm rotatably holding the paper feeding roller
102
and the idler gears
103
and
104
and rotatably held by the drive shaft
105
.
Numeral
108
indicates a separation slope surface which supports the sheets and which is at an angle &thgr; with respect to the sheet stacking surface
101
, numeral
109
indicates a lower guide which is integral with the separation slope surface
108
and which guides the lower side of the sheets fed, and numeral
110
indicates an upper guide for guiding the upper side of the sheets. Numeral
111
indicates a conveying roller which rotates to thereby apply to the sheets fed a conveying force for guiding the sheets in a predetermined direction, and numeral
112
indicates a rotatable conveying roller arranged opposite to the conveying roller
111
. Numeral
113
indicates a roller holder which rotatably holds the conveying roller
112
and which is held by the upper guide, etc., and numeral
114
indicates a conveying spring which biases the roller holder
113
and which presses the conveying roller
112
against the conveying roller
111
.
Numeral
115
indicates a conveying guide for guiding the lower side of the sheets between the paper feeding and the fixing unit. Numeral
116
indicates a toner cartridge, numeral
117
indicates a development drum in the toner cartridge, numeral
118
indicates a transfer roller which is pressed against the development drum
117
and rotates and which transfers the toner image on the development drum
117
to the sheet, numeral
119
indicates a fuser for fixing the toner image to the sheet, numeral
120
indicates a heating device for heating the toner and sheet in the fuser
119
, and numeral
121
indicates a fixing roller which rotates as it presses the sheet against the heating device
120
to convey the sheet.
Numeral
128
indicates a scanner for writing the latent image on the development drum
117
by a laser beam or the like, numeral
129
indicates an optical stand securing the scanner in position, and numeral
130
indicates an electrical portion formed by a power source for the entire image forming apparatus, a control circuit, etc.
Numeral
122
indicates a paper discharge roller pair A for conveying the sheet after fixing, numerals
123
and
124
indicate an upper paper discharge guide and a lower paper discharge guide for guiding the sheet conveyed by the discharge roller pair A, numeral
125
indicates a paper discharge roller B for discharging the sheet guided by the paper discharge guides
123
and
124
to the exterior of the image forming apparatus, numeral
126
indicates a rotatable paper discharge roller pressurized toward the paper discharge roller B
125
, and numeral
127
indicates a paper discharge tray on which the sheets discharged are stacked.
The paper feeding operation of the paper feeder constructed as described above will now be described.
The drive shaft
105
is driven by a controllable drive mechanism (not shown). As a result, the starting and stopping of the paper feeding operation is controlled. When starting paper feeding, the drive shaft
105
is driven by a drive mechanism (not shown) and rotates. This rotation is transmitted through the idler gear B
104
and the idler gear A
103
to the paper feeding roller
102
, and the paper feeding roller
102
starts to rotate. The paper feeding roller arm
107
holding the paper feeding roller
102
so as to be rotatable around the drive shaft
102
is biased so as to rotate counterclockwise as seen in the drawing by a biasing means (not shown) or by its own weight, and, by this biasing force, the paper feeding roller
102
is slightly in press contact with the upper surface of the uppermost sheet S
1
of the pile of sheets S stacked on the sheet stacking surface.
Thus, by starting rotation of the paper feeding roller
102
, a feeding force F due to frictional force is applied to the sheet S
1
. The sheet S
1
receives a reactive force F
2
from the separation slope surface
108
; due to this reactive force F
2
, the sheet S
1
is bent, whereby the sheet S
1
moves on the separation slope surface
108
, with its forward end portion abutting and being bent.
The proceeding direction of the sheet S
1
is determined by the upper guide
110
and the lower guide
109
, and it enters a nip defined by the conveying roller
112
biased toward the conveying roller
111
, and, by the rotation of the conveying roller
111
, it is further fed downward with respect to the sheet conveying direction.
The sheet S
1
is then guided by the conveying guide
115
and fed to the nip between the development drum
117
and the transfer roller
118
. The latent image written to the development drum
117
by the scanner
128
is developed in the toner cartridge
117
and transferred to the sheet by the transfer roller
118
. The toner transferred to the sheet is fixed in the fuser to the sheet, and the sheet to which the image has been fixed is stacked on the paper discharge tray
127
outside the image forming apparatus by the paper discharge roller pair A
122
and the paper discharge roller B
125
.
The above-described conventional apparatus has the following problems.
If, when inserting a pile of sheets S in the paper feeder for the purpose of supplying sheets, etc., the pile of sheet is put in by firmly abutting it against the separation slope surface
108
along the sheet stacking surface
101
or by causing it to drop in by its own weight, the forward end portion of the pile of sheets S abuts the separation slope surface
108
and is bent (buckles) as shown in FIG.
15
. When the forward end portion of the pile of sheets S is thus bent, a plurality of sheets begin to deform simultaneously at the time of paper feeding, resulting in duplicate or multifold feeding.
Further, the sheets other than the uppermost sheet are influenced by frictional force when the uppermost sheet is fed, so that, by repeating the paper feeding operation, part of the pile of sheets S is bent as shown in
FIG. 15
, resulting in multifold feeding. This often happens near the boundary between the pile of sheets S, which has been reduced in volume as a result of paper feeding, and another pile of sheet newly supplied and placed ther
Inoue Ryukichi
Matsuo Yoshihiro
Bollinger David H.
Bower Kenneth W
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
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