Sheet feeding or delivering – Feeding – With means to align sheet
Reexamination Certificate
2000-05-25
2002-06-11
Skaggs, H. Grant (Department: 3651)
Sheet feeding or delivering
Feeding
With means to align sheet
C271S254000, C271S251000, C271S264000
Reexamination Certificate
active
06402139
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sheet material feeder provided in image forming apparatuses such as printers, copying machines and facsimiles. More particularly, the present invention relates to a sheet material feeder provided with sheet-material lateral position adjusting means for adjusting a widthwise position of a sheet material (referred to hereinafter as “lateral registration”), and an image forming apparatus including the sheet material feeder.
2. Description of the Related Art
Conventional image forming apparatuses such as printers, copying machines and facsimiles sometimes include a sheet material feeder provided with a reversing mechanism for turning a sheet material upside down to print an image on the second or opposite side of the sheet material. By way of example,
FIG. 11
shows an overall construction of such a conventional image forming apparatus provided with a sheet material reversing mechanism.
In
FIG. 11
, a sheet supply cassette N accommodating a number of sheet materials S piled one above another is detachably attached to a bottom portion of an image forming apparatus body M.
Numeral
1
denotes a sheet feed roller, and
2
denotes a transport roller in pressure contact with a pair of rollers
2
a
,
2
b
. Numeral
3
denotes a register roller pair,
4
denotes a photoconductive drum, and
5
denotes a transfer roller. Numeral
6
denotes a fusing roller pair,
7
denotes a transport roller pair, and
8
denotes a transport roller capable of rotating forward and backward selectively (referred to as a “reversing roller” hereinafter). Numeral
9
denotes a semicircular roller having a semicircular shape in section, and
9
a
denotes a driven roll against which the semicircular roller
9
is brought in pressure contact. Numeral
10
denotes a transport roller pair, and
11
denotes a transport roller pair with the function of removing a curl from the sheet. Numeral
12
denotes a scanner mechanism,
13
denotes a returning mirror, and
14
denotes a sheet ejection tray. Numeral
15
denotes a flapper for changing the direction of transport of the sheet material S, and
16
denotes a guide in the form of a pair of sheet material guide plates.
A beam of light scanned by a scanner
12
is introduced to the photoconductive drum
4
after being reflected by the returning mirror
13
.
In the image forming apparatus shown in
FIG. 11
, the guide
16
serves as sheet-material lateral position adjusting means for adjusting a position of the sheet material S in the lateral direction.
FIG. 12
shows a detailed construction of a portion of the sheet material lateral position adjusting means including the guide
16
. As shown in
FIG. 12
, the guide
16
comprises left and right lateral register plates (sheet-material lateral position adjusting means)
16
a
,
16
b
each being substantially U- or channel-shaped in section. The left and right lateral register plates
16
a
,
16
b
are arranged such that their openings face each other with a predetermined spacing between the plates.
One
16
b
of the lateral register plates is attached for sliding movement on a base plate
16
c
, and is biased inward by a compression spring
17
interposed between the lateral register plate
16
b
and a spring seat
16
e
of the base plate
16
c
. The lateral register plate
16
b
engages a stopper
16
d
of the base plate
16
c
for restriction of further sliding movement and tends to be held in the engaging condition.
The base plate
16
c
of the one lateral register plate
16
b
and the other lateral register plate
16
a
are provided for movement in directions of arrows B perpendicular to the direction of transport of the sheet material, and are moved by driving means such as cylinders
19
a
,
19
b.
The cylinders
19
a
,
19
b
are controlled by a CPU (control means)
23
, which is a control unit for the entirety of the image forming apparatus, through cylinder drives
20
a
and
20
b
, respectively.
A semicircular roller
9
is disposed approximately midway between the left and right lateral register plates
16
a
,
16
b
in the direction perpendicular to the direction of transport of the sheet material, and rotation of a motor
9
b
is transmitted to the semicircular roller
9
. The motor
9
b
is controlled by the CPU
22
through a motor driver
21
.
Returning to
FIG. 11
, the sheet material S advanced by the sheet feed roller
1
from the sheet supply cassette N is introduced to a nip between the transport roller
2
and the roller
2
a
, and is further transported to the register roller pair
3
.
Then, the sheet material S is advanced by the register roller pair
3
toward the photoconductive drum
4
in timed relation therewith, and a toner image formed on the photoconductive drum
4
is transferred onto the sheet material S.
Subsequently, the sheet material S is transported to the fusing roller pair
6
for permanent fusing of the toner image. The sheet material S is then fed to the flapper
15
by the transport roller pair
7
.
In the case of printing images on both surfaces of the sheet material S, the sheet material S with an image having been printed on a first surface thereof is fed by transport roller pair
7
and guided in a direction of arrow C by the flapper
15
held in a posture indicated by broken lines, and is then introduced to the reversing roller
8
.
FIG. 13
shows in detail a manner of turning the sheet material S upside down with the reversing roller
8
. The sheet material S having been advanced in the direction C passes a crotch point
18
a
positioned at a lower end of a guide
18
, and a leading end of the sheet material S reaches sensors
23
a
,
23
b
which serve as sheet-material detecting means which are disposed downstream of the crotch point
18
a.
Upon the sensors
23
a
,
23
b
detecting the leading end of the sheet material S, a reversing roller pair
8
a
,
8
b
are rotated in directions of respective solid-line arrows to advance the sheet material S until a tailing end of the sheet material S is detected by the sensors
23
a
,
23
b.
Detection of the tailing end of the sheet material S indicates that the tailing end of the sheet material S has passed the crotch point
18
a
, and the reversing roller pair
8
a
,
8
b
are now rotated in directions of respective broken-line arrows.
Here, a nip between the reversing roller pair
8
a
,
8
b
is oriented in a direction D indicated by a broken-line arrow. Therefore, when the tailing end of the sheet material S has passed the crotch point
18
a
and the reversing operation is started, a new leading end (the tailing end before the reversing operation) of the sheet material S is forwarded to move in the direction D. The sheet material S advanced in the direction D is introduced to the guide
16
.
The CPU
22
shown in
FIG. 12
receives detection signals from the sensors
23
a
,
23
b
(these being denoted by
23
in FIG.
12
), and controls the semicircular roller
9
and the lateral register plates
16
a
,
16
b
in accordance with the received detection signals.
The sheet material S is transported in the reversed state by the reversing roller
8
, and is further transported by the semicircular roller
9
and the driven roll
9
a
until the tailing end of the sheet material S passes beyond the reversing roller
8
. The sheet material S is then stopped while it locates in channel-shaped grooves of the lateral register plates
16
a
,
16
b.
At the time when the sheet material S enters the channel-shaped grooves of the lateral register plates
16
a
,
16
b
, the lateral register plates
16
a
,
16
b
are positioned so as to provide a spacing therebetween which is greater than the width of the sheet material S. Subsequently, the base plate
16
c
of the one lateral register plate
16
b
and the lateral register plate
16
a
are moved in the directions of respective arrows B perpendicular to the direction of transport of the sheet material to reference positions that are different depending on the size of each sheet material, thereby adjust
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Skaggs H. Grant
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