EP0042860B1 - Apparatus for detecting the passage of multiple documents - Google Patents
Apparatus for detecting the passage of multiple documents Download PDFInfo
- Publication number
- EP0042860B1 EP0042860B1 EP81900285A EP81900285A EP0042860B1 EP 0042860 B1 EP0042860 B1 EP 0042860B1 EP 81900285 A EP81900285 A EP 81900285A EP 81900285 A EP81900285 A EP 81900285A EP 0042860 B1 EP0042860 B1 EP 0042860B1
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- European Patent Office
- Prior art keywords
- gauging
- documents
- modulating
- detecting
- roller
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H7/00—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles
- B65H7/02—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors
- B65H7/14—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors by photoelectric feelers or detectors
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H7/00—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles
- B65H7/02—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors
- B65H7/06—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors responsive to presence of faulty articles or incorrect separation or feed
- B65H7/12—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors responsive to presence of faulty articles or incorrect separation or feed responsive to double feed or separation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H2553/00—Sensing or detecting means
- B65H2553/40—Sensing or detecting means using optical, e.g. photographic, elements
- B65H2553/41—Photoelectric detectors
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H2701/00—Handled material; Storage means
- B65H2701/10—Handled articles or webs
- B65H2701/19—Specific article or web
- B65H2701/1912—Banknotes, bills and cheques or the like
Definitions
- This invention relates to an apparatus for detecting the passage of multiple documents in a transport system.
- the invention has application, for example, to an apparatus which monitors a currency dispenser in order to detect the simultaneous feeding of multiple bills.
- a major function of any currency dispenser is to remove bills from a stack and present them one at a time to a transport mechanism for delivery to the customer. This function may also be deemed the most critical, since problems in delivering the bills, such as failure to feed or the feeding of more than one bill at a time, generally begin at this stage. Because of the wide disparity in bill quality, ranging from new, crisp bills to limp, torn ones, as well as the occurrence of foreign matter between bills, preventing their separation, it is not possible to achieve perfect performance. Therefore, it is important to detect the problem situation and take corrective action immediately, such as the activation of a diverter gate, to capture the erroneously fed bills.
- a double document detector acknowledged in the preamble of claim 1, is described in the U.S. Patent No. 4,095,781.
- the documents are arranged to pass between a pair of cooperating rollers.
- One of the rollers is carried by a pivotally mounted bracket and is displaceable relative to the other by an extent dependent on the thickness of the documents passing between the rollers.
- the bracket has a rod attached thereto which at its other end is secured to the core of a variable displacement transformer. If more than one document is positioned between the rollers, the pivoting bracket elevates the rod and the core a distance sufficient to provide an output from the transformer to trigger associated circuitry operable to divert the multiple documents into a bin.
- a disadvantage of this arrangement is that static changes in the position of the rollers, caused by wear, elasticity or accumulation of foreign matter, may result in a drift of the operating range of the transformer causing erroneous operation.
- an apparatus for detecting the passage of multiple documents in a transport system including gauging means through which documents are arranged to pass, said gauging means being displaceable by an extent dependent on the thickness of one document or multiple documents passing therethrough; modulating means attached to said gauging means for movement therewith; detecting means positioned in operative relationship with said modulating means and arranged to produce an output in response to displacement of the latter; and circuit means responsive to said detecting means for producing an indication of whether multiple documents have simultaneously passed through said gauging means, characterized in that said circuit means include blocking means for inhibiting a voltage representative of the quiescent position of said modulating means, allowing said circuit means to respond only to changes in the position of said modulating means relative to said detecting means resulting from documents passing through said gauging means.
- Fig. 1 there are shown certain components of a currency dispenser.
- Currency bills or other documents 10 are urged against a table 12 by spring 13 for feeding.
- a pair of spaced-apart driving wheels 14, each located between two adjacent arms of an assembly 16, are fixed to a shaft 18 to be driven thereby.
- currency 10 is urged by driving wheels 14 between a pair of rollers 20 and 22.
- both rollers are composed of an aluminum core with a polyurethane covering.
- Feed roller 20 is fixed at the end of a motor shaft 24, which rotates at a surface speed of 250 centimeters per second.
- Idler roller 22 is rotatably mounted on a short shaft 26, which freely rotates in the arms of assembly 16.
- Arm assembly 16 is pivotally mounted on a shaft 28 and tensioned by a spring 30, which spring is attached to arm assembly 16 at connecting pin 32.
- the opposite end of spring 30 is attached to a short shaft 33.
- Spring 30 applies a force on arm assembly 16 such that roller 22 is urged into cooperating engagement with roller 20.
- roller 22 As currency 10 is fed between rollers 20 and 22, roller 22 is forced away from roller 20 a distance equal to the thickness of the currency 10, causing arm assembly 16 to pivot about shaft 28, and displacing the bottom of arm assembly 16 in the direction toward roller 20.
- the distance between shaft 28 and the bottom of arm assembly 16 is three times greater than the distance between shaft 28 and shaft 26; therefore, the bottom of arm assembly 16 is displaced toward roller 20 three times further than roller 22 is moved away from roller 20 when currency 10 is fed between rollers 20 and 22. Consequently, when using U.S. currency, which has a normal average thickness of 0.010 centimeters, the bottom end of arm assembly 16 will travel approximately 0.030 centimeters when a single bill passes between rollers 20 and 22.
- a processed photographic film strip 34 is bonded along a protrusion 35 on the end of arm assembly 16.
- Film strip 34 is attached to arm assembly 16 such that it moves between the light source and sensor of a detector module 36 as the bottom end of arm assembly 16 is displaced. Since film strip 34 is processed in such a manner as to exhibit a relatively rapid change in optical density in a direction parallel to its length, the described motion of arm assembly 16 will change the amount of light activating the sensor of module 36. Thus, the electrical output of detector 36 is relative to the position of arm assembly 16.
- the currency dispenser monitor is used to detect the presence of a single bill in addition to sensing the presence of multiple bills.
- the home position of rollers 20 and 22 may change.
- Causes for the position drift may be variations in the resilience of the polyurethane surface covering of the rollers, wearing of the surfaces, ink deposits from the bills, wear in the bearings, or changes in ambient temperatures which cause expansion or contraction of the machine base and components.
- Experimental analysis of this home position drift indicates that it may shift plus or minus 0.075 centimeters from its initial position. Therefore, assuming a 0.075 centimeter displacement being necessary for detecting multiple bills, a linear measurement range of 0.225 centimeters is preferred for satisfactory operation of the doubles detector.
- a low-cost and commercially-available component in the circuit of detector 36 which is pre-aligned, and has a sufficiently high electrical output to provide direct drive of the associated electronic circuitry.
- a satisfactory component is General Electric type H13B1 photon-coupled inter- ruptor module, which is composed of a gallium arsenide solid-state lamp illuminating a silicon photo-darlington sensor across an air gap of 0.318 centimeters. This component and the film strip provide the entire optical system for the present currency dispenser monitor.
- a method and apparatus for producing such a film strip is disclosed in an international application filed by the present Applicants on the same day as the present application entitled "Method and Apparatus for Fabricating a Translucent Graded Density Medium” (International Publication Number W081/01886).
- the film strip having a substantially linear density gradient enables the detector to operate over a greater travel distance. Any movement of the film will cause a change in the intensity of light which the sensor of the detector receives; therefore, the length of the filmstrip determines the operating range of the detector.
- Fig. 3 shows the electronic circuitry which, taken together with detector 36, comprises the monitor control.
- a phototransistor 40 contained within detector 36 acts as a variable resistor between the supply voltage 42, which is filtered by capacitors 43 and 44, and line 45.
- the resistance of phototransistor 40 is controlled by illumination emitted by a photodiode 46 also contained within detector 36. As the illumination from photodiode 46 increases when film strip 34 is moved in one direction within the air gap between the components of detector 36, the circuit voltage becomes more positive across a resistor 47 with respect to ground 48.
- the voltage on line 45 is also applied to a filtering combination of resistor 49 and capacitor 50.
- the coupling capacitor 50 blocks the DC component of the voltage at 45, which voltage is proportional to the quiescent position of film strip 34, arm assembly 16, and roller 22, allowing the circuit to respond only to changes in the position of film strip 34 between the components of detector 3,.
- the circuit of Fig. 3 is independent of the static position of rollers 20 and 22, and reacts only to a physical movement of roller 22, which also causes movement of arm assembly 16 and film strip 34; mechanical drift of the static roller position will not affect the proper operation of the circuit.
- Regulator 51 may be an integrated circuit chip, such as Motorola Type MC1723CL or its equivalent, and serves to insure a sufficient calibrated current supply to photodiode 46 for proper operation. Regulator 51 and its associated components (resistors 54, 56, 58 and capacitor 60) may be eliminated if the power supply used to drive the circuit is sufficiently stable.
- the output 61 of regulator 51 which is approximately 8 volts, is applied to another portion of the detection circuitry via resistors 62 and 64 and a diode 66.
- Diode 66 tends to hold the voltage across resistor 64 on the cathode of capacitor 50, which provides a fast recovery from the charge condition on capacitor 50.
- the voltage at 68 is applied to the non-inverting input 69 of a differential comparator 70 via an integrating network of resistor 72 and capacitor 74.
- Comparator 70 which may be a Motorola type MC1414L or its equivalent, detects the presence of more than one bill between rollers 20 and 22.
- the reference voltage for the inverting input 75 of comparator 70 is generated when the supply voltage at 42 is transmitted across a series combination of a resistor 78 and a zener diode 80.
- the voltage present across zener diode 80 which is approximately 3.9 VDC, is transmitted to the strobe input 81 of comparator 70, and also to input 75 via a resistor 82 and a potentiometer 84.
- Potentiometer 84 makes it possible to adjust the reference voltage for input 75 to a desired level for precise detection of a single bill thickness.
- comparator 70 outputs a fast rising TTL compatible signal at terminal 86 across a load resistor 88.
- Detection of the presence of a single bill is accomplished in a similar manner.
- the voltage at 68 is applied to the non-inverting input 90 of a differential comparator 92 via an integrating network of a resistor 94 and a capacitor 96.
- Comparator 92 may be a Motorola type MC1414L or its equivalent.
- the reference voltage across zener diode 80 is applied to the strobe input 97 of comparator 92, and also to the inverting input 98 via a resistor 100 and a potentiometer 102. Potentiometer 102 adjusts the reference voltage for input 98 to a desired level such that the signal received at input 90 exceeding this reference voltage is indicative of one or more bills passing between rollers 20 and 22.
- comparator 92 when the voltage at input 90 exceeds the reference voltage at 98 by a few millivolts, comparator 92 outputs a signal to terminal 104 across a load resistor 106, indicating the presence of at least a single bill between rollers 20 and 22.
- Fig. 4 shows the waveform of the voltage at 68 when a single bill with the leading edge folded back approximately one-half inch is inserted between rollers 20 and 22. The initial bounce caused as the bill enters rollers 20 and 22 is of sufficient amplitude to trigger comparator 70, which would output a false double detection signal.
- Fig. 5 shows the waveform of the voltage at 68 when a double bill travels between rollers 20 and 22. The signal in Fig.
- Fig. 6 shows waveforms of the signals generated by various bills at input 69 to comparator 70, which signals have been smoothed by the integrating network of resistor 72/ capacitor 74.
- Line 110 represents the double detection threshold; any signal rising above this will trigger comparator 70.
- Signal 112 represents a double bill with its leading edge folded back approximately one-half inch; it is readily detected by comparator 70.
- Signal 114 shows a double bill; it is also detected by comparator 70.
- Signal 116 represents a single bill with its leading edge folded back approximately one-half inch; the integrating network has filtered the signal so that it will not cause comparator 70 to falsely trigger.
- Signal 118 shows the waveform for an unfolded single bill; it also is not great enough to activate comparator 70.
- the idle noise of the circuitry is represented by signal 120.
- FIG. 7 shows waveforms of the signals generated by various bills at input 90 to comparator 92, which signals have been smoothed by the integrating network of resistor 94/capacitor 96.
- Line 121 indicates the present detect threshold; any signal rising above this will trigger comparator 92.
- Signal 122 represents a double bill
- signal 124 represents a single bill with the leading edge folded back one-half inch
- signal 126 represents an unfolded single bill. As shown in Fig. 7, these three signals are sufficiently high enough to surpass the present detection threshold, triggering comparator 92.
- Signal 128 represents idle noise picked up by the circuitry; it is not strong enough to activate comparator 92.
- Fig. 8 is a graph showing curves 140 and 142 representing the output voltages of two detectors with respect to the displacement of the graded density film strip which is used in the currency dispensor monitor. The graphs show that as the distance from the dark-to-light transition area of the film strip increases the output voltages of the detectors increase in a linear fashion.
- each detector can be normalized in the circuitry of Fig. 3 by adjusting potentiometer 52 until the current through photodiode 46 of the detector module 36 reaches a prescribed level while the output voltage of the phototransistor 40 is held at a fixed level.
- the current level was analytically and experimentally determined to be 590 microamps, using a 4 volt output across phototransistor 40.
- the normalized operating curves 140a and 142a of the detectors used in Fig. 8 are shown in Fig. 9.
- the graph of Fig. 9 plots the normalized detector output against the "centered" or normalized position of the film strip. Curves 140a and 142a show that, over a 0.254 centimeter range ( ⁇ 0.127 centimeters from the normalized position), the output voltages of two commercial detectors can be normalized to obtain a uniform response.
- Typical values of the. components of the circuit of Fig. 3 may be as follows:
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Abstract
Description
- This invention relates to an apparatus for detecting the passage of multiple documents in a transport system. The invention has application, for example, to an apparatus which monitors a currency dispenser in order to detect the simultaneous feeding of multiple bills.
- With the acceptance of automated financial terminals increasing rapidly, the role of the currency dispenser is growing more significant. Today terminals of this type, such as the device disclosed in U.S. Patent No. 4,168,058, serve in an important capacity in the business and financial communities.
- A major function of any currency dispenser is to remove bills from a stack and present them one at a time to a transport mechanism for delivery to the customer. This function may also be deemed the most critical, since problems in delivering the bills, such as failure to feed or the feeding of more than one bill at a time, generally begin at this stage. Because of the wide disparity in bill quality, ranging from new, crisp bills to limp, torn ones, as well as the occurrence of foreign matter between bills, preventing their separation, it is not possible to achieve perfect performance. Therefore, it is important to detect the problem situation and take corrective action immediately, such as the activation of a diverter gate, to capture the erroneously fed bills.
- A number of different techniques have been used in the past for detecting the presence of multiple bills or other documents in a transport system. These systems use mechanical, electrical, or optical devices, or a combination thereof, to sense the presence of multiple bills. Overall performance of a doubles detector, however, depends heavily on the means of determining if a document has been fed, and if so, whether it was a single document.
- A double document detector, acknowledged in the preamble of
claim 1, is described in the U.S. Patent No. 4,095,781. In this apparatus the documents are arranged to pass between a pair of cooperating rollers. One of the rollers is carried by a pivotally mounted bracket and is displaceable relative to the other by an extent dependent on the thickness of the documents passing between the rollers. The bracket has a rod attached thereto which at its other end is secured to the core of a variable displacement transformer. If more than one document is positioned between the rollers, the pivoting bracket elevates the rod and the core a distance sufficient to provide an output from the transformer to trigger associated circuitry operable to divert the multiple documents into a bin. - A disadvantage of this arrangement is that static changes in the position of the rollers, caused by wear, elasticity or accumulation of foreign matter, may result in a drift of the operating range of the transformer causing erroneous operation.
- It is an object of the present invention to provide an efficient multiple document detector with a simple, low cost, design in which the above disadvantage is alleviated.
- Thus, according to the invention, there is provided an apparatus for detecting the passage of multiple documents in a transport system, including gauging means through which documents are arranged to pass, said gauging means being displaceable by an extent dependent on the thickness of one document or multiple documents passing therethrough; modulating means attached to said gauging means for movement therewith; detecting means positioned in operative relationship with said modulating means and arranged to produce an output in response to displacement of the latter; and circuit means responsive to said detecting means for producing an indication of whether multiple documents have simultaneously passed through said gauging means, characterized in that said circuit means include blocking means for inhibiting a voltage representative of the quiescent position of said modulating means, allowing said circuit means to respond only to changes in the position of said modulating means relative to said detecting means resulting from documents passing through said gauging means.
- One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:
- Fig. 1 is a diagrammatic view illustrating certain components of a currency dispenser;
- Fig. 2 shows a partial sectional view of the currency dispenser taken along the line 2-2 of Fig. 1;
- Fig. 3 is a schematic diagram of the monitoring circuitry of the currency dispenser;
- Fig. 4 shows the unfiltered waveform of a single bill passing through the currency dispenser with its leading edge folded over;
- Fig. 5 shows the unfiltered waveform of a double bill passing through the currency dispenser;
- Fig. 6 shows the waveforms of several bills as inputs to the doubles detection comparator;
- Fig. 7 shows the waveforms of several bills as inputs to the presence detection comparator;
- Fig. 8 is a graph of the output voltages of several detectors versus displacement of the film strip;
- Fig. 9 is a graph of the normalized output voltage of several detectors versus displacement of the film strip from the energized center position.
- Referring now to Fig. 1, there are shown certain components of a currency dispenser. Currency bills or
other documents 10 are urged against a table 12 byspring 13 for feeding. A pair of spaced-apartdriving wheels 14, each located between two adjacent arms of anassembly 16, are fixed to ashaft 18 to be driven thereby. During the feeding operation,currency 10 is urged by drivingwheels 14 between a pair ofrollers Feed roller 20 is fixed at the end of amotor shaft 24, which rotates at a surface speed of 250 centimeters per second. Idlerroller 22 is rotatably mounted on ashort shaft 26, which freely rotates in the arms ofassembly 16.Arm assembly 16 is pivotally mounted on ashaft 28 and tensioned by aspring 30, which spring is attached toarm assembly 16 at connectingpin 32. The opposite end ofspring 30 is attached to ashort shaft 33.Spring 30 applies a force onarm assembly 16 such thatroller 22 is urged into cooperating engagement withroller 20. For a more detailed description of the above-described structure, reference is made to the previously-mentioned U.S. Patent No. 4,168,058. - As
currency 10 is fed betweenrollers roller 22 is forced away from roller 20 a distance equal to the thickness of thecurrency 10, causingarm assembly 16 to pivot aboutshaft 28, and displacing the bottom ofarm assembly 16 in the direction towardroller 20. In the present embodiment, the distance betweenshaft 28 and the bottom ofarm assembly 16 is three times greater than the distance betweenshaft 28 andshaft 26; therefore, the bottom ofarm assembly 16 is displaced towardroller 20 three times further thanroller 22 is moved away fromroller 20 whencurrency 10 is fed betweenrollers arm assembly 16 will travel approximately 0.030 centimeters when a single bill passes betweenrollers - A processed
photographic film strip 34 is bonded along aprotrusion 35 on the end ofarm assembly 16.Film strip 34 is attached toarm assembly 16 such that it moves between the light source and sensor of adetector module 36 as the bottom end ofarm assembly 16 is displaced. Sincefilm strip 34 is processed in such a manner as to exhibit a relatively rapid change in optical density in a direction parallel to its length, the described motion ofarm assembly 16 will change the amount of light activating the sensor ofmodule 36. Thus, the electrical output ofdetector 36 is relative to the position ofarm assembly 16. - In the present embodiment, the currency dispenser monitor is used to detect the presence of a single bill in addition to sensing the presence of multiple bills. However, due to several different factors, the home position of
rollers - In the preferred embodiment, for cost considerations it is desirable to use a low-cost and commercially-available component in the circuit of
detector 36 which is pre-aligned, and has a sufficiently high electrical output to provide direct drive of the associated electronic circuitry. A satisfactory component is General Electric type H13B1 photon-coupled inter- ruptor module, which is composed of a gallium arsenide solid-state lamp illuminating a silicon photo-darlington sensor across an air gap of 0.318 centimeters. This component and the film strip provide the entire optical system for the present currency dispenser monitor. - These detector units, however, have an active optical area of only 0.050 to 0.075 centimeters. Therefore, if the film strip contained a sharp opaque/transparent transition line, the desired range of 0.225 centimeters could not be reached. To expand the operating range, an incrementally graded density film strip is used.
- A method and apparatus for producing such a film strip is disclosed in an international application filed by the present Applicants on the same day as the present application entitled "Method and Apparatus for Fabricating a Translucent Graded Density Medium" (International Publication Number W081/01886).
- The film strip having a substantially linear density gradient enables the detector to operate over a greater travel distance. Any movement of the film will cause a change in the intensity of light which the sensor of the detector receives; therefore, the length of the filmstrip determines the operating range of the detector.
- Fig. 3 shows the electronic circuitry which, taken together with
detector 36, comprises the monitor control. Aphototransistor 40 contained withindetector 36 acts as a variable resistor between thesupply voltage 42, which is filtered bycapacitors line 45. The resistance ofphototransistor 40 is controlled by illumination emitted by aphotodiode 46 also contained withindetector 36. As the illumination fromphotodiode 46 increases whenfilm strip 34 is moved in one direction within the air gap between the components ofdetector 36, the circuit voltage becomes more positive across aresistor 47 with respect toground 48. The voltage online 45 is also applied to a filtering combination ofresistor 49 and capacitor 50. The coupling capacitor 50 blocks the DC component of the voltage at 45, which voltage is proportional to the quiescent position offilm strip 34,arm assembly 16, androller 22, allowing the circuit to respond only to changes in the position offilm strip 34 between the components ofdetector 3,. Thus, the circuit of Fig. 3 is independent of the static position ofrollers roller 22, which also causes movement ofarm assembly 16 andfilm strip 34; mechanical drift of the static roller position will not affect the proper operation of the circuit. - Current to operate
photodiode 46 is supplied from avoltage regulator 51 via apotentiometer 52.Regulator 51 may be an integrated circuit chip, such as Motorola Type MC1723CL or its equivalent, and serves to insure a sufficient calibrated current supply to photodiode 46 for proper operation.Regulator 51 and its associated components (resistors - The
output 61 ofregulator 51, which is approximately 8 volts, is applied to another portion of the detection circuitry viaresistors diode 66.Diode 66 tends to hold the voltage acrossresistor 64 on the cathode of capacitor 50, which provides a fast recovery from the charge condition on capacitor 50. - The voltage at 68 is applied to the
non-inverting input 69 of adifferential comparator 70 via an integrating network ofresistor 72 andcapacitor 74.Comparator 70, which may be a Motorola type MC1414L or its equivalent, detects the presence of more than one bill betweenrollers input 75 ofcomparator 70 is generated when the supply voltage at 42 is transmitted across a series combination of aresistor 78 and azener diode 80. The voltage present acrosszener diode 80, which is approximately 3.9 VDC, is transmitted to thestrobe input 81 ofcomparator 70, and also to input 75 via aresistor 82 and apotentiometer 84.Potentiometer 84 makes it possible to adjust the reference voltage forinput 75 to a desired level for precise detection of a single bill thickness. Thus, when the voltage atinput 69 exceeds the reference voltage at 75 by a few millivolts, indicating that a doubles condition has occurred,comparator 70 outputs a fast rising TTL compatible signal atterminal 86 across aload resistor 88. - Detection of the presence of a single bill is accomplished in a similar manner. The voltage at 68 is applied to the
non-inverting input 90 of adifferential comparator 92 via an integrating network of aresistor 94 and acapacitor 96.Comparator 92 may be a Motorola type MC1414L or its equivalent. The reference voltage acrosszener diode 80 is applied to thestrobe input 97 ofcomparator 92, and also to the invertinginput 98 via aresistor 100 and apotentiometer 102.Potentiometer 102 adjusts the reference voltage forinput 98 to a desired level such that the signal received atinput 90 exceeding this reference voltage is indicative of one or more bills passing betweenrollers input 90 exceeds the reference voltage at 98 by a few millivolts,comparator 92 outputs a signal toterminal 104 across aload resistor 106, indicating the presence of at least a single bill betweenrollers - The necessity for the integrating network of
resistor 72/capacitor 74 is illustrated by the waveforms shown in Figs. 4 and 5. Fig. 4 shows the waveform of the voltage at 68 when a single bill with the leading edge folded back approximately one-half inch is inserted betweenrollers rollers comparator 70, which would output a false double detection signal. As a comparison, Fig. 5 shows the waveform of the voltage at 68 when a double bill travels betweenrollers bill entering rollers comparator 70 for a longer time period, due to the extra thickness along the entire length of the bill. When the integrating network is used, the initial bounce is softened, allowingcomparator 70 to detect only true double bills. - Fig. 6 shows waveforms of the signals generated by various bills at
input 69 tocomparator 70, which signals have been smoothed by the integrating network ofresistor 72/capacitor 74.Line 110 represents the double detection threshold; any signal rising above this will triggercomparator 70. -
Signal 112 represents a double bill with its leading edge folded back approximately one-half inch; it is readily detected bycomparator 70.Signal 114 shows a double bill; it is also detected bycomparator 70.Signal 116 represents a single bill with its leading edge folded back approximately one-half inch; the integrating network has filtered the signal so that it will not causecomparator 70 to falsely trigger.Signal 118 shows the waveform for an unfolded single bill; it also is not great enough to activatecomparator 70. Finally, the idle noise of the circuitry is represented bysignal 120. - A lesser degree of integration is provided by the integrating network of
resistor 94/capacitor 96, which balances the signal to eliminate noise pulses from mechanical shock, and yet preserve the pulse width as a means of detecting the time of bill entry and removal fromrollers input 90 tocomparator 92, which signals have been smoothed by the integrating network ofresistor 94/capacitor 96.Line 121 indicates the present detect threshold; any signal rising above this will triggercomparator 92. -
Signal 122 represents a double bill, signal 124 represents a single bill with the leading edge folded back one-half inch, and signal 126 represents an unfolded single bill. As shown in Fig. 7, these three signals are sufficiently high enough to surpass the present detection threshold, triggeringcomparator 92.Signal 128 represents idle noise picked up by the circuitry; it is not strong enough to activatecomparator 92. - Due to the fact that commercially available pre-aligned detector modules do not necessarily exhibit precisely identical characteristics, the operating curves of different detectors may vary. Fig. 8 is a
graph showing curves - To achieve uniform results from the monitor using commercially available detectors, it is necessary to normalize the output of the detector at a known point in the linear region of its operating curve. Referring to Fig. 8, it can be seen that if the film strip is "centered" at a displacement of 0.317 centimeters, a linear operating range of 0.254 centimeters can be easily obtained from
curves potentiometer 52 until the current throughphotodiode 46 of thedetector module 36 reaches a prescribed level while the output voltage of thephototransistor 40 is held at a fixed level. The current level was analytically and experimentally determined to be 590 microamps, using a 4 volt output acrossphototransistor 40. The normalizedoperating curves 140a and 142a of the detectors used in Fig. 8 are shown in Fig. 9. The graph of Fig. 9 plots the normalized detector output against the "centered" or normalized position of the film strip.Curves 140a and 142a show that, over a 0.254 centimeter range (±0.127 centimeters from the normalized position), the output voltages of two commercial detectors can be normalized to obtain a uniform response. -
Claims (9)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10887479A | 1979-12-31 | 1979-12-31 | |
US108874 | 2002-03-29 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0042860A1 EP0042860A1 (en) | 1982-01-06 |
EP0042860A4 EP0042860A4 (en) | 1982-04-22 |
EP0042860B1 true EP0042860B1 (en) | 1984-07-25 |
Family
ID=22324555
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP81900285A Expired EP0042860B1 (en) | 1979-12-31 | 1980-12-23 | Apparatus for detecting the passage of multiple documents |
Country Status (4)
Country | Link |
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EP (1) | EP0042860B1 (en) |
JP (1) | JPS56501801A (en) |
DE (1) | DE3068754D1 (en) |
WO (1) | WO1981001827A1 (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4650991A (en) * | 1983-07-01 | 1987-03-17 | De La Rue Systems Limited | Method and apparatus for sensing sheets |
EP0168202B1 (en) * | 1984-06-28 | 1988-09-14 | De La Rue Systems Limited | Method and apparatus for monitoring sheets |
US5577720A (en) * | 1995-04-04 | 1996-11-26 | Interbold | Self-adjusting sensor |
US6765191B2 (en) * | 2001-08-20 | 2004-07-20 | The Goodyear Tire & Rubber Company | Roller switch |
US6734417B2 (en) * | 2002-05-08 | 2004-05-11 | Hewlett-Packard Development Company, L.P. | Displacement measurement system and sheet feed system incorporating the same |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2445046A (en) * | 1944-01-22 | 1948-07-13 | Armour Res Found | Apparatus for showing pressure versus volume diagram |
US3337739A (en) * | 1967-01-13 | 1967-08-22 | Sigma Instruments Inc | Condition control galvanometer with photoelectric limit sensing |
US3770965A (en) * | 1972-05-01 | 1973-11-06 | Lewis Eng Co | Photosensitive control apparatus with movable light control member |
JPS5253105Y2 (en) * | 1973-04-27 | 1977-12-02 | ||
US4095781A (en) * | 1976-09-17 | 1978-06-20 | The Mosler Safe Company | Currency dispensing apparatus |
US4168058A (en) * | 1977-11-30 | 1979-09-18 | Ncr Corporation | Record member feeding device |
US4160546A (en) * | 1977-12-23 | 1979-07-10 | Burroughs Corporation | Document overlap-detecting apparatus and process |
-
1980
- 1980-12-23 EP EP81900285A patent/EP0042860B1/en not_active Expired
- 1980-12-23 JP JP81500504A patent/JPS56501801A/ja active Pending
- 1980-12-23 WO PCT/US1980/001720 patent/WO1981001827A1/en not_active Application Discontinuation
- 1980-12-23 DE DE8181900285T patent/DE3068754D1/en not_active Expired
Non-Patent Citations (1)
Title |
---|
IBM TECHNICAL DISCLOSURE BULLETIN, vol. 19, no. 12, May 1977 ARMONK (US) W.A. BOOTHROYD "Double document detect system", pages 4749-4750 * |
Also Published As
Publication number | Publication date |
---|---|
WO1981001827A1 (en) | 1981-07-09 |
JPS56501801A (en) | 1981-12-10 |
EP0042860A4 (en) | 1982-04-22 |
DE3068754D1 (en) | 1984-08-30 |
EP0042860A1 (en) | 1982-01-06 |
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