Sheet feeding or delivering – Feeding – Separators
Reexamination Certificate
2000-10-12
2003-04-01
Walsh, Donald P. (Department: 3651)
Sheet feeding or delivering
Feeding
Separators
C221S109000, C221S121000
Reexamination Certificate
active
06540219
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to a paper feed apparatus. More particularly, the invention relates to a paper feed apparatus of a bottom discharge type having an automatic paper feed apparatus for use in image reading system where paper sheet separating performance for separating paper sheets being fed, such as manuscripts and cut sheets, can be enhanced, and operability can be improved by eliminating the need for special preliminary operations when setting paper sheets.
BACKGROUND ART
Most image reading devices for reading a large amount of manuscripts transported automatically have an automatic paper feed apparatus comprising a paper pickup mechanism for causing a plurality of paper sheets stacked on a chute to move to a predetermined standby position, a separating mechanism for separating and picking up and transporting the paper sheets onto the standby position one by one, a feed mechanism for transporting the paper sheet, and a paper discharge mechanism for discharging the paper sheets after image reading to a stacker or outside the paper feed apparatus. In recent years, the aforementioned automatic paper feed apparatus is controlled by a microprocessor in most cases.
FIG. 27
is a diagram illustrating a prior-art paper feeding apparatus. In the figure, a pickup roller
72
and a separating roller
73
are disposed so that both the rollers
72
and
73
can be rotated in the same direction via a gear
83
, and also can be rotated in conjunction with a feed roller
74
via a gear
79
, The pickup roller
72
is caused to make a sliding contact with a pressure arm
81
, and the separating roller
73
is caused to make a sliding contact with a separating pad
80
, respectively. A gate
84
is provided in a paper feed path between the pickup roller
72
and the separating roller
73
.
The pressure arm
81
, which is typically made of a spring member, is provided to ensure the transportation of a paper sheet set on the chute
71
. An end of the pressure arm
81
is fixedly fitted to a (not shown), and the other end thereof is forced onto the paper sheet by a pushing force in the direction of the pickup roller
72
. The pushing force, together with force between the pickup roller and the paper, acts to take up and transport the paper sheet to the separating roller
73
.
The gate
84
is used to provide a clearance in the direction of paper thickness in the paper feed path so that a few sheets of paper can pass, and is disposed at an acutely inclined position with respect to the direction of paper entry into the paper feed path to ensure positive paper transport.
A one-way clutch is provided on each of the shafts of the pickup roller
72
, the separating roller
73
and a discharge roller
75
so that the separating roller
73
can rotate only in a counterclockwise direction, and the discharge roller
75
only in a clockwise direction (paper feed direction). A sensor
82
for sensing the leading edge of paper is provided on the downstream side of the paper feed path near the separating roller
73
. A sensor
85
for sensing the leading/trailing end of paper is also provided on the downstream side of the paper feed path near the feed roller
74
.
In the aforementioned automatic paper feed apparatus, as a pulley
76
of a motor (not shown) is rotated in a counterclockwise direction, the feed roller
74
is rotated in a counterclockwise direction by a belt
77
, that is, in the direction opposite to the direction of paper feed. The discharge roller
75
remains stationary even when the belt
77
is rotated. The pickup roller
72
and the separating roller
73
are rotated in a counterclockwise direction by gears
79
and
83
. Consequently, paper sheets (not shown) stacked on the chute
71
are taken up one by one by the pickup roller
72
, and transported toward the separating roller
73
. Should multiple paper sheets be erroneously taken up en bloc, only one paper sheet that is in close contact with the pickup and separating rollers
72
and
73
is transported toward the feed roller
74
by the blocking action of the gate
84
and the separating pad
80
. Thus, what is called double feeding can be prevented.
Next, even when the leading edge of the transported paper sheet reaches the feed roller
74
, the paper sheet is not immediately fed to the feed roller
74
, staying there for a while because the feed roller
74
is, rotated counterclockwise, or in the direction opposite to the paper feed direction. Thus, the edge of the paper sheet is aligned during the period. The retention time of the paper sheet is controlled based on a predetermined number of pulses or a predetermined time after the sensor
82
has detected the leading edge of the paper sheet. After the lapse of a predetermined retention time, the motor (not shown) is reversed to cause the pulley
76
to rotate clockwise. As a result, the feed and discharge rollers
74
and
75
are also caused to rotate clockwise by the belt
77
, with the paper sheet transported to the reading mechanism
78
by the feed roller
74
. Immediately before it, the leading edge of the paper sheet is detected by the sensor
85
, and reading is initiated by a signal generated by the sensor
85
. As the sensor
85
detects the trailing end of paper, reading is terminated and the paper sheet is discharged onto a stacker (not shown) by the discharge roller
75
.
In the aforementioned automatic paper feed apparatus where multiple sheets of paper
90
as shown in FIG.
28
(
a
) are set on the chute
71
, a preparatory operation is required to form the leading edges of the paper sheets into a knife edge
91
, or cause the leading edges of the paper sheets to feather, as shown in
FIG. 28
(
b
), to ensure that paper sheets are taken up onto the separating roller
73
smoothly and positively.
As described above, the paper feed apparatus of the prior art has the following problems:
(1) Since the gate for providing a clearance in the paper thickness direction in the paper feed path is disposed at an acutely inclined position to the paper entry direction, the resulting vertical component force produces a force contributing to unwanted multiple-sheet feeding, lowering the paper separating performance.
(2) When setting multiple sheets of paper on the chute, a preparatory operation is needed to form the leading edges of paper sheets into a knife edge (or cause the front face of the paper stack to feather). This preparatory operation, however, is so complex that the operator is often induced to neglect it. This may result in failure to ensure smooth paper feeding.
(3) As described above, the separating roller is disposed between the pickup and feed rollers, and the pickup roller is caused to make sliding contact with the pressure arm, and the separating roller with the separating pad. All these arrangements have made the transport mechanism of the prior-art paper feed apparatus an oversized unit.
It has been required that the aforementioned problems in the prior-art paper feed apparatus be solved, and that all paper sheets, large or small, be properly supplied in the paper feed apparatus. That is, pickup errors that could happen when handling a large amount of paper sheets, or multiple-sheet feeding associated with a small number of paper sheets, or paper jams associated with thin paper sheets must be prevented.
It is an object of this invention to provide a paper feed apparatus that can feed paper sheets properly.
DISCLOSURE OF THE INVENTION
To overcome the above-mentioned problems, a paper feed apparatus embodying the present invention employs the following means:
In a paper feed apparatus having a pickup mechanism to pick up a plurality of sheets of paper stacked on a chute one by one from the bottom, and carrying the paper sheet to a predetermined preparatory position;
a gate disposed facing the pickup roller almost vertically with respect to the direction of paper entry to form a predetermined clearance, a paper-sheet separating pad making sliding contact with the pickup roller to pick up the paper sheets placed on the prepar
Kumon Kouichi
Naruse Akira
Sato Mitsuru
Bower Kenneth W
PFU Limited
Walsh Donald P.
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