US 5,853,089 AGranted

Apparatus for detecting multiple superposed sheets

AssigneeNCR Corporation

InventorDouglas L. Milne

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Abstract

An apparatus for detecting the passage of superposed sheets, e.g. deposited currency notes, along a feed path includes a mechanism which has a pair of cooperating rollers (42,44) and which is arranged to generate an output voltage whose magnitude varies in response to the passage of an item (single or multiple sheet) between the rollers (42,44). Samples of this output voltage are taken during one complete revolution of one of the rollers (42,44). These samples are processed to generate a value representative of the cross-sectional area of said item. In order to take account of sheets of different sizes, a further value is generated representative of the dimension of said item parallel to its direction of feed. The value representing said cross-sectional area is divided by this further value in order to derive a value which represents the average thickness of said item and which enables a determination to be made as to whether said item is a single or multiple sheet.

Claims18

Dependent claims

An apparatus for detecting the passage of superposed sheets along a feed path, said apparatus comprising:

first and second cooperating rollers, said first roller having a fixed axis of rotation;
means for feeding sheets along said feed path between said rollers;
means for mounting said second roller so that its axis is movable relative to that of said first roller and so that it is biased towards said first roller to enable said second roller to be displaced away from said first roller in response to a single or multiple sheet passing between said first and second rollers;
voltage generating means associated with said second roller and arranged to produce an output voltage which varies linearly with movement of the axis of said second roller towards or away from the axis of said first roller;
analog-to-digital converter means to which said output voltage is applied;
pulse generating means for generating timing pulses in timed relationship with the revolution of said rollers;
first sensor means for sensing the presence of an item comprising a single or multiple sheet as it passes a point in said feed path;
and
data processing means connected to the outputs of said converter means, said pulse generating means and said first sensor means, said data processing means being arranged to perform the following steps:
(a) sampling the value of said output voltage, as represented by the output of said converter means, a predetermined number of times for one complete revolution, or for an integral number of complete revolutions, of one of said rollers when no sheet is passing between said rollers;
(b) storing a first digital value representative of the sum of the values of said output voltage sampled in step (a);
(c) sampling the value of said output voltage, as represented by the output of said converter means, said predetermined number of times for one complete revolution, or for an integral number of complete revolutions, of said one of said rollers when said item is passing between said rollers;
(d) storing a second digital value representative of the sum of the values of said output voltage sampled in step (c);
(e) subtracting said first digital value from said second digital value to produce a third digital value;
(f) counting the number of pulses generated by said pulse generating means while said first sensor means is sensing the presence of said item and thereby generating a fourth digital value representative of the dimension of said item corresponding to its direction of feed along said feed path;
(g) dividing said third digital value by said fourth digital value to provide a fifth digital value representative of the mean thickness of said item;
and
(h) making a determination as to whether or not to reject said item on the basis of said fifth digital value.

15 more elements

An apparatus for detecting the passage of superposed sheets along a feed path, said apparatus comprising:

first and second cooperating rollers, said first roller having a fixed axis of rotation;
a feeder unit for feeding sheets along said feed path between said rollers;
a support structure for mounting said second roller so that its axis is movable relative to that of said first roller and so that it is biased towards said first roller to enable said second roller to be displaced away from said first roller in response to a single or multiple sheet passing between said first and second rollers;
a voltage generating unit associated with said second roller and arranged to produce an output voltage which varies linearly with movement of the axis of said second roller towards or away from the axis of said first roller;
an analog-to-digital converter unit to which said output voltage is applied;
a pulse generating unit for generating timing pulses in timed relationship with the revolution of said rollers;
a first sensor unit for sensing the presence of an item comprising a single or multiple sheet as it passes a point in said feed path;
and
a data processing unit connected to the outputs of said converter unit, said pulse generating unit and said first sensor unit, said data processing unit being arranged to perform the following steps:
(a) sampling the value of said output voltage, as represented by the output of said converter unit, a predetermined number of times for one complete revolution, or for an integral number of complete revolutions, of one of said rollers when no sheet is passing between said rollers;
(b) storing a first digital value representative of the sum of the values of said output voltage sampled in step (a);
(c) sampling the value of said output voltage, as represented by the output of said converter unit, said predetermined number of times for one complete revolution, or for an integral number of complete revolutions, of said one of said rollers when said item is passing between said rollers;
(d) storing a second digital value representative of the sum of the values of said output voltage sampled in step (c);
(e) subtracting said first digital value from said second digital value to produce a third digital value;
(f) counting the number of pulses generated by said pulse generating unit while said first sensor unit is sensing the presence of said item and thereby generating a fourth digital value representative of the dimension of said item corresponding to its direction of feed along said feed path;
(g) dividing said third digital value by said fourth digital value to provide a fifth digital value representative of the mean thickness of said item;
and
(h) making a determination as to whether or not to reject said item on the basis of said fifth digital value.

15 more elements

A method of detecting the passage of superposed sheets along a feed path between a first roller and a second roller which is movable away from the first roller in response to an item comprising a single or multiple sheet passing between the first and second rollers, the method comprising the steps of:

(a) sampling the value of an output voltage a predetermined number of times for one complete revolution or for an integral number of complete revolutions of one of the rollers when no sheet is passing between the rollers;
(b) storing a first digital value representative of the sum of the values of the output voltage sampled in step (a);
(c) sampling the value of the output voltage the predetermined number of times for one complete revolution or for an integral number of complete revolutions of the one of the rollers when the item is passing between the rollers;
(d) storing a second digital value representative of the sum of the values of the output voltage sampled in step (c);
(e) subtracting the first digital value from the second digital value to produce a third digital value;
(f) counting the number of pulses generated by a pulse generating unit while a sensor unit is sensing the presence of the item and thereby generating a fourth digital value representative of the dimension of the item corresponding to its direction of feed along the feed path;
(g) dividing the third digital value by the fourth digital value to provide a fifth digital value representative of the mean thickness of the item;
and
(h) making a determination as to whether or not to reject the item on the basis of the fifth digital value.

6 more elements

Dependencies are inferred from the claim text.