Sheet feeding or delivering – Feeding – Separators
Reexamination Certificate
2000-04-10
2002-04-09
Ellis, Christopher P. (Department: 3651)
Sheet feeding or delivering
Feeding
Separators
C271S121000, C271S137000, C271S138000
Reexamination Certificate
active
06367795
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a paper feed apparatus, and more particularly to a bottom-drawing-type paper feed apparatus which is suitable for, for example, an image scanner and which has an improved sheet separation performance, eliminates necessity of a pre-operation before setting of sheets of paper to thereby facilitate operation, and prevents occurrence of a paper jam and/or upturn of a leading end of a sheet.
2. Description of the Related Art
In general, an image scanner is provided with an automatic paper feed apparatus which enables the image scanner to automatically transport and read a huge amount of documents. Such an automatic paper feed apparatus comprises a picking mechanism for transporting a plurality of sheets of paper stacked on a shooter to a predetermined standby position; a separation mechanism for drawing inside a sheet of paper at a time from the standby position; a feed mechanism for feeding the separated sheet; and a discharge mechanism for discharging the sheet to a stacker or the outside of the scanner after the sheet has been scanned. Recently, such an automatic paper feed apparatus has been controlled by means of a microprocessor.
FIG. 13
is an explanatory view showing a main portion of a conventional paper feed apparatus. As shown in
FIG. 13
, a picking roller
72
and a separation roller
73
are drivingly linked via a gear
83
so that the picking roller
72
and the separation roller
73
rotate in the same direction; and the separation roller
73
is drivingly linked to a feed roller
74
via a gear
79
. Further, a pressing arm
81
is disposed in sliding contact with the picking roller
72
, and a separation pad
80
is disposed in sliding contact with the separation roller
73
. Moreover, a gate
84
is disposed on a paper feed path between the picking roller
72
and the separation roller
73
.
The pressing arm
81
is provided in order to enable reliable transport of sheets of paper set on a shooter
71
and is formed from a spring member. One end of the pressing arm
81
is fixed to an unillustrated frame, and the other end of the pressing arm
81
is biased toward the picking roller
72
to thereby come into contact with the top sheet of paper while applying a certain pressing force to the sheets of paper. By means of frictional force which is generated between the picking roller
72
and the sheets of paper due to the pressing force, the sheets of paper are transported from the shooter
71
to the separation roller
73
.
The gate
84
is provided so as to secure a clearance in the thickness direction of sheets on the paper feed path in order to enable passage of a few sheets of paper, thereby enabling reliable transport of the sheets. The gate
84
has a paper-abutting surface which forms an acute angle with respect to the paper transport direction along the paper feed path.
A one-way clutch is attached to each of the picking roller
72
, the separation roller
73
, and the discharge roller
75
such that the separation roller
73
rotates in the counterclockwise direction in
FIG. 13
, and the discharge roller
75
rotates in the clockwise direction (paper transport direction) only. Further, a sensor
82
for detecting the leading end of each sheet of paper is disposed along the paper feed path in the vicinity of and on the downstream side of the separation roller
73
. Further, a sensor
85
for detecting the leading and trailing ends of each sheet of paper is disposed along the paper feed path in the vicinity of and on the downstream side of the feed roller
74
.
In the above-described automatic paper feed apparatus, when a pulley
76
connected to an unillustrated motor is rotated in the counterclockwise direction, a belt
77
engaged with the pulley
76
causes the feed roller
74
to rotate in the counterclockwise direction, or in a direction opposite the paper transport direction. At this time, the discharge roller
75
does not rotate even when the belt
77
moves. Meanwhile, the picking roller
72
and the separation roller
73
are rotated in the counterclockwise direction (paper transport direction) via gears
79
and
83
. Therefore, a single sheet of paper is drawn inside from the unillustrated paper stack on the shooter
71
by the picking roller
72
and is transported toward the separation roller
73
. If a plurality of sheets of paper are picked erroneously, the gate
84
and the separation pad
80
prevent transfer of the plurality of sheets, so that only a single sheet of paper in close contact with the picking roller
72
and the separation roller
73
is transported toward the feed roller
74
. Therefore, transportation of two sheets (double feed or a like) problem does not occur.
Even when the leading end of the transported sheet of paper reaches the feed roller
74
, the sheet of paper is not supplied to the feed roller
74
instantaneously but is stopped there for a short period of time, because the feed roller
74
is rotating in the counterclockwise direction, which is opposite the paper transport direction. During this period, positioning of the leading end of the sheet is performed. The stop time is controlled on the basis of a predetermined number of pulses or a predetermined period of time after the sensor
82
detects the leading end of a sheet of paper. After elapse of the predetermined period of time, the unillustrated motor rotates in the reverse direction in order to rotate the pulley
76
in the clockwise direction. Therefore, the feed roller
74
and the discharge roller
75
are also rotated in the clockwise direction via the belt
77
. As a result, the sheet of paper is transported by the feed roller
74
to a reading mechanism
78
. Immediately before the leading end of the sheet of paper reaches the reading mechanism
78
, the leading end is detected by the sensor
85
. In response to a detection signal generated by the sensor
85
, the read operation is started. When the sensor
85
detects the trailing end of the sheet of paper, the read operation is ended, and the discharge roller
75
is operated to discharge the sheet of paper onto an unillustrated stacker.
In the above-described automatic paper feed apparatus, when, as shown in
FIG. 14A
, a large number of sheets of paper
90
are placed onto the shooter
71
, the sheets of paper
90
must be aligned in a staggered manner beforehand such that the leading ends of the sheets of paper
90
form a knife-edge-like shape
91
, as shown in
FIG. 14B
, in order to make it easy to feeding the sheets of paper to the separation roller
73
.
The above-described conventional paper feed apparatus has the following drawbacks.
Since the gate—which forms a clearance in the thickness direction of sheets of paper on the paper feed path—extends at an acute angle with respect to the paper transport direction, a vertical component force is generated and is applied to the sheets of paper, resulting in an impairment in paper separation performance.
Further, when a large number of sheets of paper are placed onto the shooter, the sheets of paper must be aligned in a staggered manner beforehand such that the leading ends of the sheets of paper form a knife-edge-like shape. However, this pre-operation is considerably cumbersome, and is sometimes neglected or forgotten. In this case, sheets of paper cannot be supplied smoothly.
Moreover, the separation roller is disposed between the picking roller and the feed roller; the pressing arm is disposed in sliding contact with the picking roller; and the separation pad is disposed in sliding contact with the separation roller. Therefore, the transport mechanism portion of the paper feed apparatus has a relatively large size.
Further, since the picking roller is disposed such that a portion of the outer circumference of the picking roller is exposed to the outside from an opening provided in a paper guide, when the picking roller picks and transfers a sheet of paper, the sheet may be caught between the picking roller and the paper guide, resulting in occurrence of
Matsuda Yasuhiro
Tsuchiyama Yoshiki
PFU Limited
Shapiro Jeffrey A.
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