Sheet feeding or delivering – Delivering – With transfer means between conveyor and receiver
Reexamination Certificate
2001-06-11
2002-12-17
Skaggs, H. Grant (Department: 3653)
Sheet feeding or delivering
Delivering
With transfer means between conveyor and receiver
C271S187000, C271S315000
Reexamination Certificate
active
06494447
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to apparatus for inspecting or processing sheet materials such as bank notes, and in particular to the stacking or accumulation unit of a sheet material inspecting or processing apparatus. The stacking or accumulation unit includes at least one impeller or stacker wheel to which sheets are selectively fed following inspection or processing, a stepper motor for rotating the stacker wheel in order to accept the sheets and deposit them in a stack, and a stepper motor control circuit for synchronizing movement of the wheel with movement of the sheets by start-stop or intermittent operation of the stepper wheel. Movement of the stacker wheel is timed by the controller so that movement of the wheel occurs solely during the intervals between sheet arrivals, the wheel remaining stationary as individual sheets enter grooves in the wheel so as to prevent collisions between the arriving sheets and edges of the accumulation grooves in the wheel.
The invention also relates to a method of accumulating or stacking sheets following inspection or processing and selective diversion to a stacking or accumulation unit of the type which utilizes an impeller or stacker wheel to collect the sheets and deposit them in a stack. The method involves controlling the stacker wheel so that it moves only during the intervals between arrival of the sheets, and is stationary and perfectly positioned upon arrival of each sheet in order to prevent collisions between the arriving sheets and edges of the accumulation grooves in the wheel.
2. Description of Related Art
In general, the use of stacker wheels, also known as star wheels or accumulation impellers, for the purpose of accumulating and stacking sheet materials such as bank notes following inspection or processing, is well-known. As shown in
FIGS. 1-3
, the conventional stacker wheel
1
includes a plurality of spiral blades
4
which define accumulation grooves
5
. As the wheel is rotated so that the grooves
5
successively are presented to a sheet arrival chute
6
, the sheets are selectively diverted into the chute by a pivotal gate
7
based on the results of sheet inspection (for example, based on a determination of banknote denomination). The grooves absorb the forward momentum of the sheets so that they can be stacked without causing damage to the sheets. Following insertion of the sheets into grooves
5
, the wheel is operated in a purge mode which deposits the sheets in an accumulation tray or bin
8
.
Because of the high speed at which bank notes are processed, damage which can lead to misfeeding or jamming may occur if a sheet collides with one of the spiral blades
4
before properly entering the corresponding groove, as illustrated in FIG.
2
. The possibility of collision results from even slight differences in arrival times of the sheets at the entrance to the accumulation device.
To reduce the possibility of collision, it has been proposed to increase the entrance angle so as to decrease the likelihood that a sheet will encounter the trailing side of a blade before entering the groove, but the reduction in collisions that can be achieved is limited. A more effective, but also more difficult solution to the problem of reducing collisions and jamming has been to synchronize rotation of the wheel with detected sheet arrivals by varying the rotation speed of the wheel, and in particular by accelerating or decelerating the wheel to adjust for deviations in arrival times of the sheets at the entrance to the accumulation device.
In order to synchronize rotation of the stacker wheel with arrival of sheets, the conventional apparatus includes, as shown in
FIG. 3
, at least one optical sensor
9
positioned upstream of the stacker wheel or accumulation unit and arranged to indicate the arrival of the sheet in the entrance chute
6
. The optical sensor or sensors have outputs connected to a microcontroller
10
. Microcontroller
10
supplies timing signals to a motor controller
11
to enable the motor controller to determine the arrival time of a sheet for the purpose of adjusting the speed that the stacker wheel is rotated by stepper motor
12
, so that a sheet will begin entering one of the grooves
5
of the stacker wheel at the exact moment that the groove is aligned with the incoming sheet. In addition, microcontroller
10
synchronizes operation of the gate
7
and/or gate controller
7
′ so that notes are properly diverted into the accumulation device or sent downstream to another accumulation device or for further processing.
In the conventional method of controlling the apparatus of
FIG. 3
, as illustrated in
FIG. 4
, the motor controller
11
, upon being informed by microcontroller
10
of an incoming sheet (step
1
), calculates an arrival time for the sheet at the entrance to the groove based on the output of optical sensor
9
(step
2
). Based on the detected position or phase of the stepper motor
12
, the stepper motor controller
11
then calculates the deceleration or acceleration necessary to cause the groove to be in the proper position at the time of arrival of the sheet (step
3
). The process is repeated for the next sheet.
In this method, all speed calculations and adjustments must be carried out between the time of arrival of a sheet at the optical sensor
9
and the time of arrival of the sheet at the stacker wheel
1
. In the case of a U.S. or Canadian banknote inspection apparatus, in which individual sheets in the form of banknotes are fed at a rate of 10 sheets per second, the available time between arrival of the leading edge of one of the notes at the optical sensor and entry of the note into the stackerwheel is approximately 13.5 ms, while an additional 22 to 24 ms are required for the trailing edge of the note to enter the groove. Not only does this necessitate rapid processing capabilities, but the high torques required to accelerate or decelerate the motor in the limited time between completion of the speed calculation and arrival of the banknote places great physical demands on the conventional stepper motor used to rotate the stacker wheel.
An example of a prior continuous stacker wheel motor control arrangement which addresses the problem of high torques is disclosed in U.S. Pat. No. 5,641,156. In the system of this patent, in order to reduce the amount of acceleration or deceleration necessary to achieve precise phasing of the stacker wheel and the arriving notes, the stepper motor only accelerates or decelerates the stacker wheel if the pitch, i.e., spacing between notes is outside a predetermined range, and only accelerates or decelerates the note by an amount sufficient to bring the stacker wheel within a predetermined insertion range. In addition, an auxiliary drive is used to accelerate or decelerate the notes themselves in order to further reduce the amount by which the rotation speed of the stacker wheel needs to be varied.
Even with the modifications described in U.S. Pat. No. 5,641,156, however, sophisticated processing capabilities and a relatively high capacity motor are required in order to effect the continuous control necessary to ensure proper phasing, limiting the speed at which notes can be processed, and increasing the cost, weight, and power consumption of the device.
SUMMARY OF THE INVENTION
It is accordingly a first objective of the invention to provide a high speed sheet material processing and/or inspection apparatus of the type including a stacker wheel made up of a plurality of spiral blades defining grooves for collecting the sheets following inspection and/or processing, which minimizes the possiblity of jamming due to improperly timed arrival of the sheets.
It is a second objective of the invention to provide a high speed sheet material processing and/or inspection apparatus of the type including a stacker wheel made up of a plurality of spiral blades defining grooves for collecting the sheets following inspection and/or processing, in which successive grooves are perfectly positioned
Giesecke & Devrient America, Inc.
Skaggs H. Grant
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