Paper feeder

Details Paper feeder Paper feeder

2000-08-25

2002-05-21

Skaggs, H. Grant (Department: 3651)

Sheet feeding or delivering

Feeding

Separators

C271S121000

Reexamination Certificate

active

06390463

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of Invention
The invention relates to a paper feeder for use in an image forming apparatus, such as a copying machine, a printer, and a facsimile machine. More particularly, it relates to the paper feeder that stably feeds out paper, such as a document.
2. Description of Related Art
Conventional paper feeders that are employed in, for example, facsimile machines, include a separation roller to separate pages from a stack of documents, one by one, and a pick-up roller, disposed upstream of the separation roller in a document feeding direction, to feed out the pages in the feeding direction thereof. Typically, the separation roller and the pick-up roller are rotatably supported by a frame member.
An example of a conventional paper feeder
50
is shown in FIG.
5
.
FIG. 5
is a schematic, partially sectional side view of the conventional paper feeder
50
. A set of documents P is stacked on a paper feed slope
51
. A separation pad
52
, disposed downstream of the paper feed slope
51
in the document P feeding direction (right side in FIG.
5
), separates leading edges of the documents P, one by one. Disposed above the separation pad
52
, is a separation roller
53
. The separation roller
53
separates pages from the stack of the documents P, one by one, in cooperation with the separation pad
52
, and transfers the pages of the documents P in the feeding direction thereof. The separation roller
53
is mounted on a separation roller shaft
53
a,
which extends through the frame member
54
. The separation roller
53
is rotatably supported by the separation roller shaft
53
a,
in the body of the image reading device
2
. Mounted on the separation roller shaft
53
a,
near one end of the separation roller
53
, is a gear (not shown), that is engaged with an idle gear
56
(described below), to transmit the rotation of the separation roller
53
thereto.
Disposed on the document P feeding upstream side in the frame member
54
(left side in FIG.
5
), is a pick-up roller
55
. Similar to the separation roller
53
, the pickup roller
55
transfers separated individual pages of the documents P in the feeding direction thereof. The pick-up roller
55
is rotatably supported by a pick-up roller shaft
55
a
in the frame member
54
. Mounted on the pick-up roller shaft
55
a,
near one end of the pick-up roller
55
, is a gear (not shown) that is engaged with the idle gear
56
, to transmit the rotation of the pick-up roller
55
thereto, similar to the separation roller
53
.
Between the pick-up roller
55
and the separation roller
53
, the idle gear
56
is disposed in a position where the idle gear
56
is engaged with each gear mounted near the ends of the separation roller
53
and the pick-up roller
55
. The idle gear
56
transmits the rotation of the separation roller
53
to the pick-up roller
55
, while being engaged with the gears mounted near the separation roller
53
and the pick-up roller
55
.
The idle gear
56
is rotatably supported by an idle gear shaft
56
a,
which is provided on the frame member
54
. In
FIG. 5
, an outer circle of the idle gear
56
indicates an addendum circle. An inner circle of the idle gear
56
indicates a dedendum circle. A circle written in dot-dash lines between the outer and the inner circles of the idle gear
56
indicates a pitch circle of the idle gear
56
.
As described above, the idle gear
56
is disposed between the pick-up roller
55
and the separation roller
53
, in a position where the idle gear
56
is engaged with each gear mounted near the ends of the separation roller
53
and the pick-up roller
55
. With this structure, the separation roller
53
and the pick-up roller
55
may rotate in the same direction. A top page of the documents P, may be transferred in the feeding direction thereof, by the separation roller
53
, the pick-up roller
55
, and the separation pad
52
.
Loading a set of documents P on the paper feed slope
51
is difficult if the pick-up roller
55
makes contact with an upper surface of the paper feed slope
51
. Conventionally, a hook
54
a
protruding upwardly from an upper portion of the frame member
54
, and another hook
50
a
protruding downwardly from the body of the paper feeder
50
are connected by an extension spring
57
. A user pulls upwardly the pick-up roller
55
to load a set of documents P on the paper feed slope
51
.
As the set of documents P is loaded and the feeding thereof is started, the user moves the pick-up roller
55
down, so that the separation roller
53
and the pick-up roller
55
make contact with the top page of the documents P. Then, the separation roller
53
and the pick-up roller
55
start to rotate in the direction to feed the documents P in the feeding direction thereof.
However, with the above-described structure, the pick-up roller
55
is pulled upwardly by the extension spring
57
, even after the document P feeding is started. Therefore, the pick-up roller
55
unstably makes contact with the documents P, resulting in an unstable feeding thereof.
SUMMARY OF THE INVENTION
One aspect of the invention is to provide a paper feeder that stably feeds out paper, such as a document. To achieve this aspect, the paper feeder of the invention may include a separation roller that separates a plurality of stacked documents, one by one, a pick-up roller that is disposed upstream of the separation roller in a document feeding direction, and that feeds out the documents toward the separation roller, a frame member that supports a rotating shaft for the separation roller and a rotating shaft for the pick-up roller, and a lifting member that turns the frame member in a direction away from a document positioning portion, so as to move the pick-up roller away from the document positioning portion, by transmitting a rotation of the rotating shaft for the separation roller to the frame member, when the rotating shaft for the separation roller rotates opposite to a direction to feed the documents in the document feeding direction.
In the paper feeder, after a set of the documents has been fed, the lifting member transmits the rotation of the rotating shaft for the separation roller to the frame member, as the rotating shaft for the separation roller rotates opposite to the direction to feed documents in the document feeding direction, by a predetermined amount. Accordingly, the frame member is turned in the direction away from the document positioning portion, so as to move the pick-up roller away therefrom.
In the paper feeder of the invention, the lifting member may include a frame collar that projects from an insertion portion of the rotating shaft for the separation roller in the frame member, the frame collar placing the rotating shaft for the separation roller therein, a first collar that is disposed near the frame collar and rotatably inserted over the rotating shaft for the separation roller, a second collar that is disposed near a first collar end opposite to the frame collar, and fixedly inserted over the rotating shaft for the separation roller, a first clutch member that places the frame collar and the first collar therein, wherein when the rotating shaft for the separation roller rotates in the direction to feed the documents in the document feeding direction, the first clutch member causes the frame collar and the first collar to separately and independently act, and when the rotating shaft for the separation roller rotates opposite to the direction to the document feeding direction, the first clutch member causes the frame collar and the first collar to act as one-piece, and a second clutch member that places the first collar and the second collar therein, wherein when the rotating shaft for the separation roller rotates in the direction to feed the documents in the document feeding direction, the second clutch member causes the first collar and the second collar to act as one-piece, and when the rotating shaft for the separation roller rotates opposite to the document feeding direction, the second clutch member

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