US3412993A - Process and an apparatus for checking bank notes or bills after their printing and before their packing - Google Patents

Description

Nov. 26, 1968 G. GIORI 3,412,993

PROCESS AND AN APPARATUS FOR CHECKING BANK NOTES OR BILLS AFTER THEIR PRINTING AND BEFORE THEIR PACKING Filed June 2, 1966 5 Sheets-Sheet 1 NOV. 26, 1968 GIQRI 3,412,993

PROCESS AND AN APPARATUS FoR CHECKING BANK NOTES 0R BILLS AFTER THEIR PRINTING AND BEFORE THEIR PACKING Filed June 2, 1966 5 Sheets-Sheet 2 NOV. 26, 1968 G. GIORI 3,

' PRO ND AN ARA FOR CHECKING BANK N S BIL ER THE PRI NG AND BEFORE TH K Filed June 2, 1966 Sheets-Sheet 5 I F'IG.5b g 1 F l m t FlG.5f

FlG.5g 1 its t 5 Sheets-Sheet 4.

G. GIORI Nov. 26, 1968 PROCESS AND AN APPARATUS FOR CHECKING BANK NOTES OR BILLS AFTER THEIR PRINTING AND BEFORE THEIR PACKING Filed June 2, 1966 Nov. 26, 1968 G. GIORI PROCESS AND AN APPARATUS FOR CHECKING BANK NOTES ORv BILLS AFTER THEIR PRINTING AND BEFORE THEIR PACKING 5 Sheets-Sheet 5 Filed June 2, 1966 KFIG.7

United States Patent 8 Claims. (Cl. 270-4) 10 ABSTRACT OF THE DISCLOSURE This disclosure relates to a process and an apparatus for checking bank notes after printing and before packaging which includes a source of supply of stacks of notes having control colour marks thereon; first counting means for the notes; transport means for conveying the notes at a given speed in a certain direction to successive stations where checking operations are to be performed; first detecting means positioned after the first counting means for detecting the presence of the colour marks on either surface of the notes while they are conveyed by the transport means and for emitting a signal in the presence 2 of these marks; second detecting means including at least three photo-optical detectors positioned above and three below the transport means for checking the centering of the notes relative to the edges thereof as they are conveyed in front thereof and for emitting a signal upon the detection of an imperfect note, two of the detectors scanning at least one of the edges of the notes at two spaced reference positions, while the third detector scans one adjacent edge of the notes at a reference position; a control unit to which the signals from the first detecting means and the detectors are fed; a take-oft station controlled by the control unit with a time lag with respect to the emission of the signals for removing imperfect notes; and secand counting means for counting the checked notes.

The present invetnion has for its object a process and an apparatus for checking bank notes or bills after their printing and before their packing.

Bank notes usually leave the printing machine in the form of sheets having from 20 to 500 bills printed thereon. Before the sheets are cut into bills, and the bills stacked and packed, it is necessary to check them for printing errors. For this a specialist visually checks each bill of each sheet to determine colour errors and the presence of spots which he manually checks off on each imperfect bill of the sheet and these bills after the sheet is cut are taken out and replaced by new and usable bills. Centering errors, since they arise as a result of cutting, cannot be detected until after the sheets are cut into the required number of bank notes. This requires a second checking operation for determining the centering errors. At the end of the checking operations, the bills in perfect condition are counted, stacked, provided with bands, ticketed and packed.

While the cutting of the sheets, the cutting of the bills, the packing and the enveloping operations can be effected without difiiculty and, up to a point, automatically, the sameis not true of the operations of the very line or printing errors, of the checking off of the errors and of the replacement of the imperfect bills by new and usable bills, operations which up to now have only been performed manually. It has been noted that the overall checking process constitutes, because of its complexity and difiiculty, about of the manufacturing costs of bank notes. The greater part of the checking time is devoted to detecting centering errors. The detection of centering errors furthermore constitute a laborious and highly responsible task since the determination of such errors on bills is not easy and are much smaller than the determination of colour and spot errors.

Another drawback of the actually used processes resides in the substitution of the bills checked off as imperfect by new usable bills and that for evident security reasons. It is desirable in the field of manufacturing of bank notes to retain under permanent control these bills from the moment of their printing until their packing and to avoid all manual handling thereof during the manufacturing process. Such handling remains, however, up to noW indispensable because of the previously mentioned operations which were only manually possible.

The present nivention accordingly has for object to avoid the drawbacks and flaws of the previously employed bank note checking processes and to provide a process which allows to free checkers from the difficult visual detecting of centering errors in order to permit them to concentrate exclusively on the simple and easy checking of colour and spot errors; which process performs the replacement of imperfect bills by new and usable bills in a completely automatic fashion with a transporting device on which the cut bills are counted, stacked, ticketed and packed.

The present process facilitates considerably the work of the checker, and increases the safety of the operation because a manual checking is now effected only on the bills juxtaposed on the sheet to the exclusion of the cut bills and according accelerates the checking and substitution operations thereby cutting down the cost of checking which heretofore was very high.

The present process is characterised by the fact that the bills are first visually checked and marked with respect to colour and spot errors but to the exclusion of centering errors, that they are stored in at least one receptacle then are placed one after the other, and counted by means of a first counter in a definite position on a transporting device having a continuous movement which pass them in front of the following stations: a first detecting system responsive to the control marks borne by the bills on their upper and lower surfaces; a second photo-electric detector responsive to centering errors on the upper and lower face of the bills, a grasping device controlled with a time lag by the detecting systems, and which remove from the transporting device the imperfect bills and stores them in a receptacle as well as an automatic device which counts the checked bills, puts them in stacks, puts bands around them, tickets them, counts them at least one more time and packs them.

The first detecting system mentioned is made in such a way as to react either photo-optically to a colour mark for example a dark check mark or magnetically or electrically to a magnetic or electrically conductive mark.

The second detecting system consists of at least three photo-sensitive detectors for analysing the upper part of the bill and at least three photo-sensitive detectors for analysing its lower part, wherein a detector each time analyses the clear edge at a given spot of one of the edges of the bill and two detectors analyse the clear border at two different spots of the adjacent edge, The duration of sweeping of these three lateral regions to which correspond a maximum intensity of reflected light, with respect to the sweeping of a darken printed zone and to the reflection of the detecting rays when no bill is present in the sector analysed, or the width of the reflective zone corresponding to the clear edge of the bill, serves to measure the width of said three zones which must be checked in order to verify proper centering. Theoretical values are compared electrically with the measured values and in case at least one of these values does not check with the theoretical figures, a signal is emitted in order to bring about the substitution of the bill.

The annexed drawings describe, by way of example the claimed process and the means for carrying it out.

FIGURE 1 is a schematic block diagram of a first embodiment of the checking and packing system according to the invention permitting to check bills already numbered.

FIGURE 2 is a schematic plan view of a photo-electric detecting system.

FIGURE 3 is a schematic elevational view of the system of FIGURE 2.

FIGURE 4 represents schematically a bank note or bill to which the claimed process relates.

FIGURES 5a to 5g show voltage curves corresponding to the reactions of photo-electric detectors according to FIGURES 2 and 3 as a function of the sweeping time and corresponding to the reflected light.

FIGURE 6 is a schematic block diagram of a second embodiment of the checking and packing system according to the inventionwhich is useful for checking hills which are not numbered and which comprises a numbering machine.

FIGURE 7 shows schematically another embodiment of a detecting unit for examining one of the edges of a bill.

The first embodiment of the invention is shown in the base of a block diagram FIGURE 1. When the sheets of bank notes which have each a certain number of bills arranged and already numbered according to a predetermined order have left the printing press and have been packed, these sheets are inspected one after the other by the checker or inspector.

This worker is concerned only with colour errors or spots which might appear on the bills. The errors found are checked off by the checker, for example by crossing with a dark cross each bill having a flaw. The sheets which have come through this colour and spot check are then cut in a machine so as to provide the bank notes themselves, which are then put aside in receptacles in packs of a thousand bills for example with continuous serial numbers.

There is shown in FIGURE 1 such a receptacle at the entrance of the checking system. The stack of bills coming from receptacle 1 is subjected to a first counting operation by counter 2 in which the bills are counted a first time in stacks. The bills are then taken off one by one from the stack and placed one after the other with precision on a conveyor belt or any other moving device having continuous movement which makes them pass in front of a series of posts numbered below. The speed of the conveyor is constant.

The first detecting system 4 detects the upper as well as the lower surface of the bills checks to determine if some of them have the mark mentioned. For this purpose there is provided a detector above and a detector below the transporting device, each capable of detecting with accuracy at least the region where the mark appears on the bill. In order to avoid that the checker has to mark the bills at a precise spot on the surface there can be provided that the first detecting system covers the entire bill, by using several detection heads above and below the transporting device. This detecting system can function photo optically or can be responsive to magnetic or electric properties of the marking ink. In the case of a photooptic detection there is used advantageously the intensity value of the light reflected by the bill when hit by a luminous beam in such a way that by exceeding the lower limit of a determined reflective value, as a result of the absorption of light by a dark mark, a signal be given by the outlet of the photo detector;

This signal is then introduced in unit 9 the function of which will be described later. It is understood that in order to permit the detection of the lower surface of the bill on the transporting means, the support of these bills must have an opening thereon which is sufliciently large. Thus the bills are secured on the transport device by means of their edge, by clamping them for example, or openings are made in the transporting band in such a way that while they are supported the bills can be detected on their lower surface.

After this operation the bills pass in front of two photooptic detecting systems 5 and 6 which check the centering of the image on the bills with respect to their white edge, and the function of which will be described below with the aid of FIGURES 2 to 5. When one of these two detecting systems 5 and 6 notices a centering error, it emits a signal which is also introduced in unit 9.

The bills pass afterwards before the take-elf station 7 and the feed station 10. The devices forming these two stations 7 and 10 are controlled by units 9 with a time lag with respect to the time of emission of the outlet signals by detecting systems 4 to 6 in such a way that an imperfect bill detected by one of the detecting systems 4 to 6 can be caught in transit in front of device 7 and taken otf the transport means so as to be brought into receptacle 8. The empty spot thus provided on the transporting means can then be filled (by means of feeding device 10) by a new usable bill, taken from reserve receptacle 11, previously filled with a stack of bills belonging to a given series. After passing all the bills of a predetermined lot through the control system, the number of imperfect bills contained in receptacle 8 must be equal to the number of bills taken off in the particular series of the reserve receptacle 11. This comparison provides an additional means of checking.

The bills checked, and substituted, arrive then to a second counter 12 which effects an intermediate check, then go to automatic apparatus formed by units 13 to 20 in which the bills are enclosed in bands, ticketed, counted again and packed. The automatic units can be of conventional type and need not be described in greater detail although their combination is novel. In unit 13, the bills are, for example, grouped in packs of in which subgroups can also be made, for example in units of ten bills. In unit 14 the bills are provided with bands which unit 15 tickets by stamping in such a way that each pack bears indications characterising the same after the value of the bills-contained and the number of the series. In unit 16, ticketed packs are grouped in larger groups comprising, for example, 1,000 bills. Such a group of 1,000 bills is provided with a second hand, again ticketed by unit 17 in such a way as to mention the total of the group. Unit 18 comprises a double counting of the bills of each packet, for example, by turning over the corners of the bills on two different edges of the packs. Unit 19 serves to pack the groups in packets, for example, in suitable plastic containers. Finally the bills in packs and groups thus packed are sent toward an outlet receptacle 20.

Units 3 and 21 to 27 of FIGURE 1 show the sources of current, voltage dividers and feed amplifiers for counters for the detecting systems and for unit 9 which controls the devices for taking off and feeding 7 and 10. The values of counting can be shown in known manner on a control board and/ or serve to trigger a warning system or a stop of the system, when the absence of a bill or the presence of an extra bill is signalled by the counter.

The speed of transport of the bills can for example be of three meters per second. The assembly of the overall checking system is preferably housed in a closed frame and locked in order to prevent access to the bills. All circuits are preferably transistorised, in the form of printed circuits and made in easily interchangeable units, for example in panels. On a central control board, are mounted all the switches, control buttons and the warning lights.

There can be seen on FIGURE 4 the schematic representation of a bank note where 40 shows the edge that is normally clear white and 41 and 42 show the printed area and the limit of the printing. This limit 42 is not necessarily rectilinear and symmetrical with respect to the outer edge of the bill, as shown in the figure, but can, depending upon the images printed, be, for example, curved. Despite the arbitrary contour of the printed image which can vary from one kind of bill to the other, there can be determined by means of three measurements only the exact centering of the image, that is to say, by three lengthwise measurements. The reference intervals are designated by a1, a2 and b. The distance a1 and a2 determine the width of the clear edge of the bill on its long side A at two different places, while b indicates the width of the clear edge of the bill on its narrow side B at one spot only. Any error in centering of the image 41 modifies in every case at least one of the three values a1, a2 or b.

A change in the direction of arrow F of image 41 relative to the outer edge of the bill modifies the values a1 and a2 (in this particular case also b, which would not be the case if the printed limit of the narrow side of the bill extended parallel to the outer edge of the latter). A change perpendicular to the direction of arrow F in every case modifies the value b. A change of image 41 in any direction as a rule jointly changes the prevalues as does a rotating of image 41.

It suffices then to determine by means of the photoelectric detecting system the width of the clear edges of the bills in three different spots, located at least on two adjacent sides. The direction of movement of the bills on the transporting device corresponds to arrow F. It is necessary to proceed in such a way that the bills have a predetermined constant velocity and a constant and well adjusted position on the transport device since they must pass in front of six stations. This position of the bills can be fixed by stops or other positioning means carried by the transport device.

A detecting system formed by three individual detectors is shown on FIGURES 2 and 3 and serves to detect one of the surfaces of the bills, the other being detected by a similar system. These two systems correspond to units 5 and 6 of FIGURE 1. The detection of magnitudes a1 and a2 is effected by elements 32a and 32b, each formed by a luminous source and a system of optical focalising, by means of which thin luminous beams parallel to the large side of a bill, and perpendicular to the direction of movement respectively, designated by reference characters 32a and 32b in FIGURE 4, hit spots corresponding to those on the bills where magnitudes a1 and a2 must be read. The light reflected by the surface of the bills, or by the dark side of the transport means, in case there is no bill, is measured through slot 35a and slot 35b, respectively, of detector 31a and 31b, only the cell of which is shown on FIGURE 3, and an electronic multiplier 36 and an amplifier 37. The assembly of the optical system 32a and 32b must be regulated in two perpendicular directions by means of buttons 33a, 34a and 33b and 34b, respectively.

The third detection unit for magnitude b comprises similar units 310 to 35c. Unlike light beams 32a and 32b, light beams 32c (FIGURE 4) has a rapid linear oscillating movement perpendicular to the direction of transport of the bills the amplitude of which is greater than the value of magnitude b, in such a Way that by this oscillating sweeping movement the beam covers not only an area outside the bill but also an area located on the printed part itself. The oscillation frequency of the beam is substantially greater than the speed of transport of the bills, in such a Way, as shown by the zig zag line of FIGURE 4, the narrow side B of the bill is swept several times when the same passes.

When the bill is sent on in the direction of arrow F and beams 32a and 32b meet it, a voltage curve as a function of time is forward in the two corresponding photo-electric detectors, as shown schematically on FIGURES 5a, respectively 50, for detectors 31a and 31b. As long as the front edge A of the bill is not hit by the beans; these are practically absorbed by the dark bottom of the transport means, in such a way that the outlet voltage of the detector is practically zero.

At the moment 11, edge A comes into the field of detection and the outlet voltage of the detector reaches a maximum value resulting from the reflection of the beams on the clear edge of the bill. This voltage continues until the beams have passed the limit 42 of printing 41. Voltage V falls at that moment to a lower value resulting from the lesser reflection of the printed part of the bill.

This voltage drop occurs at instant t2 for detector 31b (FIGURE 50) and at instant 13 for detector 31a (FIGURE 5a) the latter following the former because of the smaller width all relative to width a1 (FIGURE 4). The voltage curve varies then as a function of image 41, this part of the voltage curve having no effect on the measurements.

The interval of time between t1 and t3 and t1 and t2, respectively, which is defined by an abrupt increase and by an abrupt fall of the outlet voltage of the detectors, respectively, constitutes a very direct and accurate measurement of length a1 and a2 since the speed of the bills is constant and known.

In order to make even more accurately this measurement interval, there can be made advantageously an electric differentiation by transforming the instantaneous voltage of curves 5a, respectively 5b, in a positive impulse, and a negative impulse, respectively, as shown on FIGURE 50 and 5d. The intervals of time between these impulses constitute a measure of the magnitude of length 01 and a2.

The measured time intervals, are compared with theoretical values which can be set, for example, on the control board in the form of buttons directly graduated in millimeters.

For this purpose, the intervals of time t1-t3 and t1t2 respectively are transformed in electric voltages the magnitude of which is proportional to the interval of time in which are compared the reference voltage forming theoretical values. The transformation can be effected in known manner for example by means of the charge or discharge characteristics of condensers or by using saw tooth voltages. In this case, the control buttons mentioned above represent the outlets of a potentiometer.

The theoretical values of the reference lengths a1 and a2, as well as the lengths of reference b are determined in advance for each type of bank note. As already indicated, when the effective values of the time intervals exceed their corresponding theoretical values by a predetermined given quantity, an error signal is introduced in a control unit 9 which controls devices 7 and 10, with a time lag corresponding to the time for the defective bill to go from the detector to device 7 and to the time for the resulting empty space to reach device 10, respectively.

It is necessary to provide for the determination of the reference distance b by the third detection unit that the photo-electric measurement will take place for only a well determined period of time when the length of reference b is in the field of action of the detector. For this purpose a circuit of doors ensures that at the moment when the reference length 11 reaches light beam 320 of the corresponding detector, a trigger impulse t1 be given to this detector to define the beginning of the measurement. On FIGURE 50, this moment is indicated by 4. The trigger impulse is suitably directed by one of the two previously mentioned detection units in such a way that the impulse be sent at moment t4 after a time lag exactly defined with respect to starting impulse t1.

The voltage curve shown on FIGURE 5 corresponds to the light reflected and measured by detection unit 310 during the oscillating sweeping of edge B of the bill. For as long as the light beam is absorbed on the outside of the edge of the bill in the underlying dark bottom, the outlet voltage is practically zero. It reaches its maximum value when the beam passes on the clear part of the edge and comes down, during the sweeping of the neighboring printed area, to a middle value. During the other half period of oscillation in the opposite direction, the passing of the clear edge of the bill causes again a maximum voltage which again falls to zero when the beam leaves the edge of the bill. Since the movement of the oscillating sweeping is rapid, the printed area of the bill only gives rise to a middle voltage in such a way that the maximum voltage curve appears practically constant on FIGURE 5f.

The circuit is so made that it is only taken into account for the measurement of the duration of the voltage impulse of maximum magnitude occurring immediately after the appearance of the trigger impulse at moment t4. In the showing of FIGURE 5 the voltage interval is that between moment t5 and t6. As in the case already described of the detectors, this voltage interval is changed by differentiation into a pair of impulses, that is to say, a first positive impulse at moment t5 and a negative impulse following at moment t6 (FIGURE 5g). The interval of the two impulses is again represented by an electric voltage the magnitude of which is proportional to the time interval and serves as the measured value which is compared to a theoretical value corresponding thereto and adjustable on the control panel. It is noteworthy to remark that for a measurement of the length 6 it is only the pair of impulses t5 and t6 (FIG- URE 5g) which appears following the trigger impulse t4 and the first impulse of which is positive, which is used. It will be understood that the interval of this pair of impulses forms in each case a measurement of the width of the edge of the bill at reference spot b regardless of the point of the voltage curve according to FIG- URE 5 at which the triggering impulse t4 occurs.

In effect the stepwise impulses shown on FIGURE 5) which correspond to the oscillation path of the beam during one oscillation, are symmetrical, and the two zones of maximum voltage, which correspond to the width of the clear edges of the bill, are identical.

The circuit is so made that the outlet of the detector has no influence on the measurement before moment 14 and after moment t6, in the same manner that the outlets of the two other units of detector 31a and 31b remain without effect during the sweeping of the lower edge of the bill (FIGURE 4) since the same does not participate in the measurement. Such electrical circuits for selective measurement as a function of time are well known.

It is also possible within the scope of the invention to represent the time interval determining the length b during the measurement of a maximum reflection, otherwise than by differentiation or transformation of this interval in a proportional voltage in order to compare it to a theoretical value. There can be used, for example the value of the integrated reflection.

It is also possible to provide two detectors with oscillating beams for detecting the edge of the bill parallel to the direction of transport while only one detector sweeps the adjacent edge perpendicular to the direction of transport. When the limit of the printed part of the bill is furthermore sufiiciently divergent from a line parallel to the edge of the bill it is possible not to use a detector with oscillating beams. The third detector corresponding to detection unit 31c on FIGURE 4, then covers the clear edge of the bill longitudinally until it intersects with the printed limits.

As indicated it is in every case possible by detecting the three reference lengths given for the edges of a bank note to control the perfect centering of its printing.

These references parts for the measurement are evidently selected where there occurs a good contrast between the clear edge of the bill and the sombre printing of the image.

The second embodiment of the invention is shown on FIGURE 6. The units marked 101-120 function exactly like units 1-20 of FIGURE 1, the feed station 10 and the reserve receptacle 11 having been eliminated since the bills here are given their serial numbers by a printing unit 124 after examination and determination of printing errors. In the apparatus according to FIGURE 6 it is therefore not necessary to fill the voids appearing in the succession of bills as a result of the removal of the imperfect bills. In the diagram shown on FIGURE 6, the units corresponding to units 3 and 21-27 of FIGURE 1, which contain the elements for feeding electricity and regulating the assembly are not shown.

As in the first example, the sheets leaving the printing machine and having a predetermined number of bills printed thereon, which however do not bear serial numbers, are inspected by a checker with respect to printing errors and spots. Bills having a flaw are checked in color. The checked bills and those marked are sent on toward an automatic cutting machine 100. The cut bills are stacked in a magazine 101 and arrive through a first counting device 102 on a transporting cylinder 50. As shown on FIGURE 6, the conveying system on which the bills are continually moved during the automatic checking comprises rollers 51, 52 and 53. While on the first roller 51 on which the other side of the bill is swept by tection system 104a and 105, then it is taken by second roller 51 on which the other side of the bill is swept by of the systems 104:: and 104b, in the place of detectors of systems 4 of FIGURE 1, respond to the color marks put on by the checker on the bills, while the detectors of systems 105 and 106, as in system 5 and 6 of FIGURE 1 examine the centering of the printed image with respect to the edges in the previously described manner. If a printing error is detected by the detecting system, the grasping system 107 is actuated with a certain time lag through unit 109, device 107 ensuring that the bill having the printing error be taken off by cylinder 52. All the good bills remain however for a moment on cylinder 51 and are taken off afterwards by cylinder 63.

These arrows shown on the conveying cylinders show the motion of the bills in the checking system, the bills removed because of printing errors pass from cylinder 52 into counting device 121 and are then assembled in a storage 108. The remainder of the bills is taken oif cylinder 53 goes through a counting device 122 to be collected in an intermediate storage 123. The bills then pass from the storage one by one into a numbering unit 124 and then go through another counter 112 and are then sent on to stations 113-120 in which they are stacked, ticketed, counted again and packed.

Numbering unit 124 has a printing cylinder 54, and a numbering cylinder 55 having generally several numbering mechanisms 56 as well as an inking cylinder 57 for the numbering mechanisms with a system 58 for controlling the quantity of color deposited during printing. Unit 124 also has a checking device for the numbering which watches over the correct change-over of the numbering systems after each revolution of numbering cylinder 55 and which interrupts the numbering process when a flaw is detected. In this case, the printing cylinder 54 is separated from the numbering cylinder 55 suitably by a hydraulic device before there is time to effect an incorrect impression. In this manner absolutely correct numbering of the bills leaving unit 124 is ensured thus making possible their stacking and packing without additional check- On the entrance cylinder 50 is provided additionally a device for measuring thickness which is not known and which operates mechanically r optically which ensures that only one note arrives on the transport system and not several superimposed notes.

On FIGURE 7 is shown schematically a detecting unit for exploring the edge 40 of the bank note and therefrom for checking the centering. In this embodiment the detector serves to sweep the reference systems as indicated with respect to FIGURE 4 and to determine the normalised width of the edge of the note measured along the narrow side B. This side B extends parallel to the direction of movement of the bills while the reference distance b is perpendicular to the latter. As above, 41 represents the color imprint on the note and 42 the limit of this imprint. While in the first example the detecting ray 32c sweeping the reference system b makes a rapid oscillating movement, detecting unit 61 of FIGURE 7 does not move. This detecting unit 61 is constructed in such a way that the duration during which the detector sweeps the reference distance b which corresponds to a zone of maximum reflection, is not measured. For this purpose, detector 61 is provided with artificial fibres which conduct light and which are known as fibre optics, the faces of which receiving the light are indicated on FIGURE 7 and designated by the reference character 62. On this plurality of surfaces receiving incident light, there is projected by means of a lens 61 the zone to be checked of the edge of the note to the reference length b in such a way that the number of neighbouring fibres 62 lit by reflection constitute an exact measure of the width of the reference length. The image of the reference distance projected on the incident surfaces of the synthetic fibres is designated by small b. There is determined in an electronic comparator 63, if the number of illuminated fibres during this brief measurement corresponds to the determined value. If this is not the case, an error signal is sent on through unit 109 of FIGURE 6 to the grasping device 107 in order to remove the note having this printing error. The measurement signal for sweeping the reference b is as described in the first embodiment and is individually triggered with a suitable time lag for each note when the front edge A of the note reaches a certain position relative to the detecting system. It is advisable to use for the triggering of the measurement signal, the reaction signal of one of the other detectors which sweep the reference length a1 and a2 respectively of the large front edge of the note. With the aid of the detecting unit described, it is thus possible to determine at the very moment of measurement, the exact number of synthetic fibres having received enough light reflected by the clear edge of the bill independently of the position of the zone of the synthetic fibres of the beam receiving the light. The bill can then be slightly shifted perpendicularly to its direction of transport during its passage in the detector without this shift resulting in an effect of the measurement. The image b of the length of the reference light b, would be displaced on the beam of the synthetic fibres, the number of fibres illuminated remaining unchanged.

The number of illuminated fibres is obtained by means of optical detectors associated with each of the fibres of the beam in such a way that in unit 63 the number of energized detectors during the measurement can be compared with a pre-established value.

The detection systems described with respect to FIG- URE 7 can be used for the direct measurements of the length of other reference lengths a1 and a2 according to FIGURE 4, instead of the detecting systems of FIGURES 5a and 5g.

It will be understood that a number of modifications, alterations and mechanical improvements may be made in the present system while remaining within the province of the invention.

What is claimed is:

1. Apparatus for checking bank notes after printing and before packaging comprising in combination a source of supply of stacks of notes having an imprint and control colour marks thereon; first counting means for said notes; transport means for conveying said notes at a given speed in a certain direction to successive stations where checking operations are to be performed; first detecting means positioned after said first counting means for detecting the presence of said colour marks on either surface of said notes while they are conveyed by said transport means and for emitting a signal in the presence of said mark; second detecting means, comprising at least three photo-optical detectors positioned above and three below said transport means for checking the centering of said imprint of said notes relative to the edges thereof as said notes are conveyed in front of said detectors and adapted to emit a signal upon detection of an imperfect note; two of said detectors scanning at least one of the edges of said notes at two spaced reference positions, the third detector scanning one adjacent edge of said notes at one reference position; a control unit to which said signals from said first detecting means and said detectors are fed; a take off station controlled by said control unit with a time lag with respect to the emission of said signals for removing imperfect notes and second counting means for counting the checked notes.

2. Apparatus according to claim 1, wherein the first two detectors scan one edge perpendicular to the direction of movement of said notes and the third detector scans one edge parallel to the direction of movement, said third detector being operative only when said reference position passes within the detecting range of said detector.

3. Apparatus according to claim 2, wherein said third detector sweeps the note with a rapidly oscillating linear movement perpendicular to the direction of motion thereof, the velocity being essentially greater than the velocity of movement of said notes.

4. Apparatus according to claim 2, wherein at least said third detector is stationary and comprises a band of light-conducting fibers onto the light-receiving surface of which is projected the length of said reference length under said stationary detector; there being a comparison unit for comparing the widths composed of a determined number of fibers, with a reference value stored in the comparing unit.

5. Apparatus according to claim 1, having an electrical delaying circuit controlling the measuring time of said third detector, said third detector being switched on only by a trigger impulse produced by one of said other detectors which detects a first edge of said notes after a predetermined time lag in relation to the passage of the first edge of the note perpendicular to the direction of movement of the note.

6. Apparatus according to claim 1, having transport means comprising a first rotating drum located near colour mark detecting means and a photo-optical detector for checking one side of the notes on the said drum; a second rotating drum parallel and co-operating with the first drum for picking up said notes on their reverse side; colour mark detecting means and a photo-optical detector positioned near said second drum; a movable take-off drum controlled by signals emitted by said detecting 1 1 1 2 means and detectors for removing imperfect notes; means References Cited for conveying the notes remaining on said second drum UNITED STATES PATENTS to a first counting device; a numbenng device for consecutively numbering the counted notes and a second 2,773,596 12/1956 Bartlett 250 219 counting device 5 3,051,841 8/1962 Crosfield et a1. 209--11l.7 X 7. Apparatus according to claim 1, having a feed sta- 3,093,729 6/1963 Pnce at 209111-7 tion for replacing imperfect notes with usable notes, and FOREIGN PATENTS controlled also by said control unit. 1,268,549 6/1961 France 8. Apparatus according to claim 1, having numbering means positioned after said take off station for number- 10 EUGENE R. CAPOZIO Primmy Examine:

ing the checked notes remaining after removal of said imperfect notes PAUL V. WILLIAMS, Assistant Exammer-

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