CN1048103C - Counterfeit document detection apparatus - Google Patents

Abstract

An equipment for stock management (10) comprises a forged stock detecting system identifying doubtful forged stocks according to the magnetism of the stock (22). Every stock (22) is transmitted near a readout magnetic head (86) producing an electric signal (210), and a circuit adjustment (110) adjusts the electric signal (210) from the readout magnetic head (86), which makes the electric signal (210) compatible with a module or number switching device (304). The circuit adjustment (110) including one or a plurality of amplifiers (130), a filter (140), a rectifier (160) and an integraph (180) provides an adjustment signal (220) from an integraph (180) to the module or number switching device (304) and restricts the adjustment signal (220) to a compatible PWL. When detecting each stock (22), a plurality of sampling values are gained through the module or number switching device (304) and by accumulating the sampling values, one or a plurality of accumulative values (242, 274, 292, 404, 412) representing the stock (22) are produced. Compared the accumulative values with one or a plurality of predetermined reference values (263, 264, 276, 280, 282, 288, 402, 406, 410, 414) related to a true stock, one can make sure whether the stock (22) is a doubtful forged stock (22) or not.

Description

Counterfeit securities detection equipment

The invention relates to a device and a method for magnetically detecting suspicious counterfeit bills.

Document counting and handling equipment that counts, verifies, and stacks certain types of securities, such as currency, is well known. Among these is a device that utilizes an analog comparison circuit to verify that the optical and magnetic properties of a document fall within thresholds determined by discrete electronic components that bias the comparison circuit. In order to use these devices to count and verify documents that differ in their optical or magnetic properties, the biasing elements of the analog comparator circuits must be adjusted manually. A specific combination of verification tests may be implemented in prior art security counting devices suitable for one type of security (e.g., U.S. currency), but this specific combination may not be suitable for other types of security, such as coupons, U.S. Food stamps, or currencies of countries other than the United States. Accordingly, it would be desirable to provide a control system for a document counting device which would allow selective verification checks by the counting device and which would allow easy selection of check thresholds and steps to suit the characteristics and characteristics of various documents.

We have found that accurate inspection of documents based on their optical and magnetic properties is difficult in high speed document counting equipment due to the presence of electrical noise in the counting equipment from various noise sources. In order to increase the reliability of authentic document verification, it is desirable to provide a document verification system which is substantially immune to the influence of electrical noise.

In accordance with one aspect of the present invention, a programmable microprocessor controlled control system is provided for document counting and sorting equipment. The microprocessor is connected to a channel analog-to-digital (A/D) converter which samples analog signals from optical and magnetic document detection equipment. As each document is processed, the microprocessor accumulates multiple sampled values from the sensors via the A/D converter. The accumulated samples are compared to programmable thresholds and/or limits to verify each document as it is conveyed through the device. Thresholds and limits for testing document magnetism are selected by the user at a time, or these thresholds or limits are reprogrammed (which is easily done) to test different types of documents. For example, updating non-volatile memory (containing test parameters and control programs executed by the microprocessor) may facilitate such reprogramming.

According to another aspect of the present invention, a document counting apparatus includes a document magnetic inspection system for documents having magnetism, and the system is characterized by reducing the effects of noise. Magnetic document inspection systems employ a read head that generates an induced electrical signal in response to passage of a magnetic document across the head. The heads are rigidly mounted to a security guide. In one embodiment of the present invention, a document enhancing magnet is also rigidly mounted to the read head in fixed relation to form a single mechanical connection with the read head. Path-constraining wheels positioned above the read head cause the document to pass in uniform proximity near the read head as the document is conveyed along the guide plate. Signal conditioning circuitry processes the induced electrical signal from the read head to provide a conditioned signal with a low noise content. In a preferred embodiment, the signal conditioning circuit includes a bandpass filter for removing high frequency noise components and low frequency noise components of the induced electrical signal from the read head. During the passage of the document through the read head, the processed signal is sampled a number of times by the A/D converter to produce a value which is accumulated by the microprocessor. After the document has passed the read head, the accumulated values are averaged and compared to one or more predetermined reference values to verify that the document has predetermined or acceptable magnetic properties or magnetism.

According to another embodiment of the present invention, a counterfeit document detection system is provided for a document counting device so that it can be used to test documents having different magnetic properties. Such securities (such as the 50-yuan note issued by the People's Republic of China) have weaker magnetic fields and/or smaller magnetic regions than U.S. currency. A high-gain, low-noise signal conditioning circuit is provided for an enhanced counterfeit detection system in the detection and verification of relatively small magnetizable documents to interface between the read head and the control microprocessor. As each document travels past the read head, the A/D converter takes a plurality of signal samples of the conditioning signal under microprocessor control. Each sampled value is compared to one or more reference values against which the microprocessor counts cumulatively the number of successive sampled values falling within a predetermined range of the reference values. The accumulated counts are in turn compared to one or more reference values associated with authentic documents to determine whether the documents being processed have acceptable magnetic properties.

The following summary and the following detailed description of the preferred embodiments of the invention will be better understood when read in conjunction with the accompanying drawings, in which:

Figure 1 is a perspective view of a document counting and sorting device according to the present invention;

Figure 2A is a sectional view showing the structural arrangement of the structural components of the document counting and sorting apparatus of Figure 1 taken along line 2A-2A of Figure 1 and partially broken;

Figure 2B is a side view of the document counting and sorting device of Figure 1 taken along line 2B of Figure 1 and with the housing removed;

Figure 2C is a side view of the document counting and sorting apparatus of Figure 1 with the housing removed, in section taken along line 2C of Figure 1;

Figure 2D is a schematic plan view showing the drive train of the apparatus of Figure 1 with the guide plates removed, the side plates broken, and the overlap separated for clarity;

Figure 3A is a partial cross-sectional view showing the location of the optical and magnetic sensors in the document counting and sorting apparatus of Figure 2A, and showing another stripping assembly with parts removed for clarity;

Figure 3B is a plan view of the stripping adjustment mechanism of the stripping assembly taken along line 3B-3B of Figure 3A;

Figure 3C is a perspective view of the peel adjustment mechanism of Figure 3A;

Figure 4 is a plan sectional view of the guide plate showing the position of the optical and magnetic sensors of Figure 3 as viewed along line 4-4;

Figure 5A is a schematic block diagram of a magnetic signal conditioning circuit according to the present invention;

Fig. 5B is a graph showing the input and output waveforms of the circuit of Fig. 5A;

Figure 5C is a schematic diagram of a preferred embodiment of the circuit shown in Figure 5A;

Figure 6A is a schematic block diagram of a control system for the document counting and sorting apparatus of the present invention;

Fig. 6B is a schematic diagram of an electromechanical timing wheel providing a timing signal to the control system of Fig. 6A;

7A-7E are several successive parts of the logic flow diagram of the control process executed by the control system of FIG. 6A, including another counterfeit bill detection process;

Fig. 8 is a plan view of the control panel of the device shown in Fig. 1;

Fig. 9 is a schematic diagram of the back of a Chinese 50-yuan banknote, showing the magnetic part;

Figure 10A is a schematic diagram of another magnetic signal conditioning circuit according to the present invention;

Figure 10B is a schematic diagram of a power supply circuit for use with the circuit of Figure 10A; and

FIG. 11 is a graph of signal waveforms generated by the signal conditioning circuit of FIG. 10A.

FIG. 1 shows a value document counting and sorting device 10 . In the plant 10, the securities are placed in the hopper 12, whereby the securities are sent to the plant 10 for counting or sorting. The securities pass through the device 10 and are stacked on the stacking plate 20 by stacking wheels 18 . The control panel of the device includes a display 16 (eg, an LCD display) that displays counts, totals and status information to the user. Control commands are manually entered into the device using the keyboard 14 .

As far as the document delivery mechanism is concerned, referring now to FIG. 2A, a stack of securities 22 is placed in the hopper 12 and they rest on the hopper plate 24. Referring now to FIG. An LED 65 and a light sensor 64 are aligned on both sides of the hopper 12 to detect the presence or absence of securities in the hopper 12 . A pair of sorting wheels (eg, sorting wheels 26 ) are installed on the sorting wheel shaft 28 , and the shaft 28 is located below the bin plate 24 . A frictional sorting surface 30 surrounds a portion of the perimeter of the sorting wheel 26 . Upon rotation of the sorting wheel 26, the sorting surface 30 passes through an aperture in the bin plate 24, frictionally engages the lowermost documents 22, and forces these documents 22 toward the feed wheel assembly 32.

When the feed wheel 32 is in frictional engagement with the lowermost securities, the peel assembly (generally indicated by reference numeral 36) provides a peeling action in a direction opposite to the direction of rotation of the feed wheel 32, squeezing the lowermost securities so that the securities are formed one at a time. With this device, a more comprehensive description will be given below. Stripping assembly 36 is driven by drive shaft 48 on which is mounted drive pulley 40 . Drive pulley 40 engages friction belt 38 of the stripping assembly, and belt 38 rotates about drive pulley 40 and idler pulley 42 mounted on idler shaft 44 . The stripping assembly belt 38 is selected to have a lower coefficient of friction with the securities 22 than with the peripheral surface of the supply wheel 32 so that the stripping action does not overcome the feeding action of the supply wheel 32.

It often happens that the frictional properties of a security (eg, cash) depend on the age and condition of the security, and also on environmental properties (eg, humidity). In order to adjust the peeling friction applied to the securities 22 as the securities 22 are added to the apparatus, the idler shaft 44 is provided with a rotatable eccentric bearing 46 which can be rotated to adjust the position of the idler shaft 44 relative to the drive shaft 48 . This adjustment changes the tension in the stripping assembly friction belt 38 and can be used to vary the normal force applied to the document 22 by the stripping assembly friction belt 38 as the document is introduced into the apparatus 10.

Figure 3A shows a preferred alternative stripping assembly, generally designated 36a. Tension idler pulley 70 engages stripping assembly belt 38 between drive pulley 40 and idler sheave 42a. Tension idler pulley 70 maintains tension in stripping assembly belt 38 by preventing inward deformation of the loop formed by stripping assembly belt 38 as the document is forced toward the surface of stripping assembly belt 38 . The tension idler pulley 70 is mounted on a shaft 72 which is suspended from the stripping assembly drive shaft 48 by a pivotable bracket 71 .

As can be seen from FIG. 3B, the idler sleeve 47 is free to rotate on the idler shaft 73a. The idler shaft 73 a is fastened to the side plates 33 and 34 by screws 113 . Returning now to Fig. 3A, it can be seen that the surface of the flange 63a is in contact with the surface of the feed wheel 32, so that the securities and the feed wheel remain in frictional contact, and the securities are drawn along the guide path between the flange 63a and the feed wheel 32. push forward. Returning to FIG. 3B, there is shown a bracket 114, indicated generally at 114, pivotally supported on idler shaft 73a. One end of the short shaft 44 a is fixed to the bracket 114 by a screw 115 . The tension adjusting wheel 42a is rotatably mounted on the short shaft 44a near the end of the short shaft 44a opposite to the screw 115. As best seen in FIG. 3A , the tension adjustment wheel 42 a engages the lower end of the stripping assembly friction belt 38 .

Referring now to FIG. 3C, therein the bracket 114 has a pair of cleats 106 and 107 at the opposite end thereof to the pivotable end on the idler shaft 73a. A cam 117 is eccentrically mounted on the adjustment shaft 116 between the bridges 106 and 107 . As best seen in FIG. 3A, rotation of the cam 117 on the adjustment shaft 116 enables the splint end of the bracket 114 to pivot about the pivotable end of the bracket 114 on the shaft 73a. When the bracket 114 rotates, the short shaft 44a can vertically move up and down by virtue of the installation relationship between the short shaft 44a and the bracket 114 . Stub shaft 44a translates vertically with corresponding up and down movement of wheel 42a, thereby increasing and decreasing tension in stripping assembly 38. It should therefore be appreciated that the cam 117 is clamped or retained by the bracket so that the bracket pivots about the idler shaft 73a, and that other means than the clamp end may be utilized to clamp the cam through the bracket.

Returning now to FIG. 3B , the adjustment shaft 116 is shown secured to the side wall 34 by screws 119 . The cam 117 is preferably rotated by turning the thumbwheel 118, which is free to rotate on the adjustment shaft 116 and which may be mounted to the cam 117 or formed integrally with the cam 117. Thumbwheel 118 preferably protrudes from a cutout in rear portion 31 of the device for easy access. When the stripping assembly belt 38 is adjusted to a desired tension, the thumbwheel 118 can be held in place by friction through a compression spring 121 mounted on the adjustment shaft 116 and between the thumbwheel 118 and the side wall 34 .

The functional relationship between the structural components of device 10 is apparent from Figures 2A-2D. As shown in FIG. 2A, document guide 50 is attached to side panels 33 and 34 in known manner, such as by L-shaped brackets (bracket 35 being a typical example of such a bracket). Two sorters 26 are provided for the sorting shaft 28 in thrust bearings 61 on the side plates 33 and 34 . There are teeth 27 on the sorting shaft 28 which mesh with idler teeth 25 on the idler shaft 23 which fits in bearings 29 on the plates 33 and 34 .

Idler gear 25 meshes with stripping assembly gear 39 on stripping assembly drive shaft 48 which fits in bearings 49 on side plates 33 and 34 .

Stripping assembly drive shaft 48 has a concentrically positioned stripping assembly drive pulley 40 keyed thereto. Stripping assembly friction belt 38 meshes with drive pulley 40 , idler pulley 42 on adjustment shaft 44 .

Mounted on bracket 71 is a tension idler wheel 70 supported by but not rotating on shaft 48 in a manner similar to that shown in U.S. Patent No. 4,416,449 issued November 22, 1993 , the content of this patent disclosure is incorporated herein by reference.

The adjustment shaft 44 is fitted to the side plates 33 and 34 by means of an eccentric bearing member 46, which is of a known type and is rotatably fixed in a desired position so that the friction belt of the strip assembly 38 to get the desired tension.

On drive shaft 48 is a pair of pulleys 43 spaced from pulley 40 and keyed to shaft 48 as shown in FIG. Grooves (not shown) are provided on the document guide plate 50 to allow the O-ring 43a to contact the document 22 . The direction of rotation of the pulley 43 is opposite to that of the document feeding device, so the O-ring 43a provides additional stripping action.

When there is no bond between the supply wheel assembly 32 and the stripping assembly friction belt 38 , the outer surface of the belt 38 will be in contact with the idler sleeve 132 in the supply wheel assembly 32 . The feed wheel assembly 32 is keyed to a feed shaft 37 which fits in bearings 41 located on side plates 33 and 34 .

As shown in FIG. 20, the feed wheel assembly 32 includes a central idler sheave 132 and feed pulleys 133 keyed to the shaft 37 on each side. The feed pulleys 133 have outer friction linings 32a for frictionally engaging the documents as they are advanced by the sorting assembly 26. Idler sheave 132 is free to rotate on supply shaft 37 and the surface of idler sheave 132 is recessed relative to the supply pulley to accommodate the opposite direction of rotation of stripping assembly friction belt 38 .

The feed shaft 37 has an additional pair of feed wheels 135 keyed to the shaft 37 and having o-rings 136 on the wheels 135 for frictional engagement with the securities 22. The gear 45 on the supply shaft 37 meshes with the idler gear 25 .

The supply shaft 37 has at its end opposite the gear 45 a drive pulley 122 keyed thereto. Timing belt 125 meshes with drive pulley 122 and with motor pulley 322 on output shaft 323 of drive motor 321 mounted to side plate 34 as best seen in Figure 2C.

The driving motor 321 shown in FIG. 2D is of a conventional type, and is connected to a power source (not shown) through a motor control circuit to be described below.

Timing belt 125 also meshes with pulley 59 on accelerator shaft 56 which fits in bearings on side plates 33 and 34 . Speeder shaft 56 has a pair of speeder bushings 52 keyed to shaft 56 and having smooth outer gripping surfaces 52a to grip and speed up the securities, as will be described more fully below. Path constriction wheel 62 is keyed to the central portion of acceleration shaft 56 .

Timing belt 125 is ridged to provide reliable slip-free transmission between motor 321 and pulleys 122,59.

A pair of speed idler gears 54 are provided which contact the surface 52a of the bushing 52 and are mounted on the speed idler shaft 58 . The shaft 58 is held by a spring loaded bracket assembly 69 mounted on the underside of the document guide.

Acceleration hubs 52 and wheels 54 grip and accelerate each document, thereby providing a gap between the documents, and adding each document to stacking wheel 18 in turn. Path constraint wheels 62 force the document against the magnetic sensors, as described more fully below.

Keyed to the acceleration shaft 56 is a known timing disc 74 with LED/light sensor pairs 75 and 78 of known type mounted adjacent to the disc 74, and available from Honeywell. Optical sensor 78 scans timing disk 74 and provides a timing pulse to the central processing unit described below for each predetermined incremental movement of disk 74. The preferred incremental distance moved during the timing pulse provided by optical sensor 78 during the movement of puck 74 is equivalent to the surface movement of accelerator wheel 52a in the order of 1 millisecond.

On idler shaft 23 there is an overrunning freewheel assembly 190 of known type, assembly 190 comprising a pulley 190 of known type with a belt 192 engaged therewith, on wheel 23 by means of a conventional one-way clutch (not shown). ) stops rotating rear wheel 190 and continues to rotate.

The belt 192 engages a pulley 193 on a stack shaft 194 which fits in bearings 95 on the side plates 33 and 34 .

The stacking shaft 194 has a pair of stacking wheels 18 keyed thereto for stacking the securities D on the stacking plate 20 .

The stacking wheel 18 has a drum portion 199 which is mounted to the shaft 194 . The drum portion 199 has a plurality of spaced apart curved fingers 196 which are angled to protrude from the portion 199 and are elevated. Stacked on board 20 one at a time.

The stacking plate 20 is also provided with a pair of separate and vertically extending security stops 68 for stacking securities.

Returning now to FIG. 2A, it can be seen that after the peeling action has been applied to the documents, the documents are pushed between the supply wheel 32 and the idler wheel 63 mounted on the idler shaft 73 to continue. The function of the idler wheel 63 is that when the feeder wheel 32 pushes the document toward the acceleration wheel 52 mounted on the acceleration shaft 56, the idler wheel 63 can keep the document in frictional engagement with the supply wheel 32. Acceleration wheel 52 forms a wheel gap together with the idler wheel 54 that is contained on the acceleration idler shaft 58. The acceleration wheel 52 and the acceleration idler wheel 54 increase the speed at which the documents are moved, thereby providing a space between documents advanced by the supply wheel 32 . Determine the position of acceleration wheels 52 and 54, make them close to supply wheel 32 and idler wheel 63 as far as possible along the direction of lower guide plate 50, make securities can be with supply wheel 32 and between idler wheel 63, between acceleration wheel 52 and 54 Between, and between the fingers of the stacking wheel 18, the wheel gaps are successively in continuous contact. Such continuous contact avoids reliance on inertial movement of the document, providing controlled transport through the device.

Continue to move toward the stacking wheel 18 along the lower guide plate 50 after the securities are accelerated. The periphery of the stacking wheel 18 has a plurality of protruding fingers 196 which lift documents from the lower guide plate 50 and place them on the stacking wheel 20 . LEDs 67 and light sensors 66 are aligned on both sides of the stacking wheel 20 to detect the presence or absence of documents on the stacking wheel 20. Light sensors 64 and 66 may be photodiodes, phototransistors, or other equivalent devices. Security Sensor

As far as the detection process of the securities passes through the equipment, several control and calculation operations are performed through the equipment control network while the securities pass through the equipment. In order to provide an accurate count of acceptable documents, the apparatus includes detection means for detecting mistransmitted documents or documents not meeting predetermined suitability or reliability criteria, hereinafter referred to as false documents or suspected counterfeit documents. As soon as the device detects a mistransferred or substandard document, it stops functioning and the user can remove the erroneous document. When an erroneous document is detected, a message representing the type of error is displayed on the display 16 . Mistransmitted erroneous securities include stuck securities, in which securities partially overlap, and coincident securities, in which securities completely overlap. Sticky documents are detected by length error due to their unusual length relative to other documents of the same type. Overlapping documents are detected in terms of opacity errors due to their abnormal opacity relative to the range selected by the operator. Misfit securities include inaccurately sized securities and suspected counterfeit securities. Referring now to the dimensions of the security 100 shown in FIG. 4, the "half" error is defined as not exceeding a predetermined length threshold in the x-axis direction, and the "width deviation" error (sometimes referred to as "shortage error") is defined as the The axis direction fails to exceed a predetermined width threshold, as represented by document 100 in connection with FIG. 4 .

Several sensors (part of the machine control system) are used to detect the magnetic properties of the document as it passes near the accelerator wheels 52, 54 of the machine. As shown in FIG. 3A , a light source, such as a central LED 81 , is positioned above the lower guide plate 50 near the center of the document guide path. The central LED 81 emits light, which is detected by a light sensor (such as the central sensor 80 ) installed below the lower guide plate 50 , so that whether there is a document between the LED 81 and the sensor 80 can be optically detected. As shown in FIG. 4, the center sensor 80 is mounted in the hole 51 in the lower guide plate 50. As shown in FIG. The left sensor 82 is installed in the hole 53 on the left side of the lower guide plate 50 . Right sensor 84 is contained in the hole 55 on the right side of lower guide plate 50. When the left and right sensors 82, 84 are used to detect the presence and light-shielding properties of the left and right sections (indicated generally by reference numerals 99, 97 in FIG. 4) of the document detected by the sensor when the document is conveyed along the lower guide plate 50 near the sensor. The left and right sensors 82,84 are coordinated with the corresponding left and right LED'83,85. LED'83, 85 are mounted in the upper guide plate in a similar arrangement to the central LED 81 and central sensor 80 described in connection with Figure 3A. It should be noted that the relative positions of the LED's and light sensors provided in the upper and lower guide plates, respectively, can be reversed without affecting the detection of documents passing therethrough. It should further be noted that light sources other than LED's and light detectors other than phototransistors may be used in other ways to achieve the detection functions described herein. Finally, note that the left, right and center light sensors are shown in Figure 4 as being oriented in a line across or perpendicular to the document guide path, but these sensors may have different orientations.

Magnetic inspection is also performed on documents passing through the device. Returning now to Fig. 3, a magnetic field detector is installed on a circular plate 90 below the guide plate 50, such as the read head 86, to determine the position of the magnetic field detection amount so that it protrudes slightly above the surface of the lower guide plate 50 . The read head 86 is preferably a full track single head manufactured by Michigan Magnetics Inc. of Vermontville, Michigan, with a nominal inductance of 300mH, an impedance of 2kΩ at 1KHz, and a DC resistance of 270Ω. Read head 86 provides electrical signals representative of the magnetic properties and properties of documents advancing along lower guide plate 50 . To enhance the induced electrical signal, a flux source, such as a permanent magnet 88, is positioned below the lower guide plate 50 to magnetize the document before it passes over the read head 86.

Mechanical vibrations in the device have a tendency to introduce undesired changes in the electrical signal of the read head 86, which may be due to vibration induced relative position between the read head 86 at the magnet 88, and the document passing over the read head 86. ups and downs. To minimize vibration of magnet 88 relative to read head 86, magnet 88 and read head 86 are mounted in rigid, fixed relationship to each other forming a single structural unit. For example, in the preferred embodiment, the circular plate 90 is secured to the lower guide plate 50 by rigid fixtures (eg, stud bolts 92), and the magnets 88 are also secured by rigid fixtures (eg, stud bolts 94). Be fixed on the lower guide plate 50. Fixing both read head 86 and magnet 88 to lower guide plate 50 constrains relative vibration or movement between head 86 and magnet 88 . Also note that magnet 88 may be rigidly secured to circular plate 90 to which read head 86 is also secured.

In order to minimize the distance variation between the document and the read head 86, the path of the document above the read head 86 is limited by the path constraining wheel 62 keyed to the acceleration shaft 56. The surface of the path-constraining wheel extends below the upper guide plate 60 to form a narrow gap in the vicinity of the read head 86 . This narrow gap formed between the path constraining wheel 62 and the read head 80 ensures that the read head 86 can detect or scan documents passing over the read head 86 substantially uniformly, accurately detecting suspected counterfeit documents. The path-constraining wheel 62 conducts a uniform magnetic inspection of the securities, without jamming the crimped securities, which often occurs when using fixed path-constraining components to complete similar functions in prior art equipment of.

FIG. 4 shows the position of the read head 86 relative to the optical sensors 80,82,84. Read head 86 protrudes through aperture 57 in lower guide plate 50 at a location slightly forward of photosensors 80, 82 and 84 with respect to the direction of document transport (as indicated by arrow 101). A document of value, such as a dollar bill generally indicated at 100, is conveyed along lower guide plate 50 in the direction indicated by arrow 101 . Dollars (eg, US$ 100) feature a non-magnetic central portion 104 and a peripheral ink portion 102 that is magnetic. Thus, when the dollar bill 100 passes the magnetic head 86, the induced electrical signal generated by the read head 86 is characterized by two periods of irregular intensity representing the passage of the head and tail peripheral portions of the magnetic ink portion 102 of the dollar bill 100. 86.

The electrical signal generated by the read head 86 in response to the passage of documents is processed by the magnetic signal conditioning circuit 110 shown in FIG. 5A. Conditioning circuit 110 performs several signal processing functions to extract and amplify components of the electrical signal from read head 86 into a form suitable for analog-to-digital conversion. The read head 85 is connected to the pickup circuit 120 . The pickup circuit 120 generates a pickup signal 210, a typical pickup waveform is shown in FIG. 5B. The pickup signal 210 is mainly 60Hz, 200mv peak-to-peak leakage noise from the power supply of the device. For clarity of presentation, the noise component of signal 210 due to electrical noise from the motor due to vibration is not shown. Time t1 represents the time at which the leading edge of the document having a peripheral portion of magnetic ink begins to pass over the read head 86 . The ink pattern on the document causes the frequency component of the pickup signal 210 to vibrate significantly above 60 Hz. This low amplitude oscillation temporarily diminishes as the non-magnetic portion of the document passes the read head 86 . This low amplitude oscillation reappears in the pickup signal 210 after the non-magnetic portion of the document has passed. Time t3 represents the time when the trailing edge of the document passes the read head 86 and the low amplitude oscillations cease. The frequency distribution of low-amplitude oscillations caused by the passage of securities is significantly lower than the frequency range of vibration noise and motor noise. Returning now to Figure 5A, the pickup signal 210 is applied to a pre-amplification stage 130 which amplifies the pickup signal to a level suitable to extract the low amplitude oscillations caused by the magnetic ink portion of the document. The preamplified signal is applied to a bandpass filter 140 . The upper and lower half power point frequencies of the bandpass filter are selected to substantially remove low frequency power supply noise and high frequency vibration and motor noise from the preamplified signal. We have found that a passband from about 250 Hz to about 1600 Hz is suitable for this purpose. The band-pass filter 140 can be a two-stage amplifier connected in series with a high-pass stage and a low-pass stage, or a single-stage band-pass amplifier.

Once the desired frequency range has been extracted by the bandpass filter 140 , the filtered signal is applied to a second amplification stage 150 . The second amplification stage 150 amplifies the filtered signal to a level suitable for analog-to-digital conversion and finally threshold estimation. The second amplification stage 150 preferably includes both a variable gain stage 154 and a fixed gain stage 152 . The purpose of providing variable gain stage 154 is to adjust the gain of amplifier 150 to compensate for variations in the pickup signal amplitude. Such changes may be caused by changes in the operating speed of the equipment.

After having been amplified to a level suitable for digital conversion, the amplified signal is applied to a rectifier 160 which rectifies the amplified signal so that subsequent integration yields a positive value. The rectified signal is then applied to an integrator 180 which integrates the rectified signal. The integrator is designed to have a finite integration time. The limited integration time of the integrator 180 reduces the sensitivity of the conditioning circuit 110 to momentary fluctuations in the rectified signal, so that digital samples taken from the integrated signal yield magnetic properties or magnetic properties representative of the document detected over a finite time period. The sampled value of the property. The finite integration time of integrator 180 also compensates for the time lag between magnetic and optical detection caused by wobbles in the relative positions of read head 86 and optical sensors 80 , 82 , 84 along lower guide plate 50 . Another benefit gained by the integrator is that the integrated signal does not drop to zero during the time that the non-magnetic portion of the document is present on the read head 86 . The upper limit of acceptable integration time is determined by the short intervals between bills being applied to the device. The integration time must be short enough to allow signal decay so that the amplitude of the integrated signal does not drag out too long between successive securities. We have found that an integration time of around 2 milliseconds is suitable for a security counting speed of approximately 1200 securities/minute.

FIG. 5B shows the integrated signal, ie, the adjustment signal 220, produced by the integrator. Conditioning signal 220 is characterized by two peaks of about 4 volts which occur substantially simultaneously with the passage of a magnetized peripheral portion of a document over read head 86 . As can be seen by comparing the pick-up signal 210 and the conditioning signal 220, the influence of the 60 Hz power supply noise in the conditioning signal 220 is reduced to the extent of occasional spikes. By adjusting the rise and fall of signal 220 over a wide range, the time interval between t1 and t3 during the passage of the document over read head 86 can be discerned. The time that the document is over the light sensors 80, 82 and 84 occurs during the time interval between t2 and t4. The optical detection interval lags slightly behind the magnetic detection interval between t1 and t3. The limited integration time of the integrator 180 ensures that the adjustment signal 220 always has a significantly reliable amplitude that coincides with the light detection interval.

A detailed schematic circuit diagram of the conditioning circuit 110 is shown in FIG. 5C. Circuit 110 includes several linear operational amplifier stages (preferably constructed from LM324 operational amplifiers) to perform the signal processing functions described in connection with Figure 5B. Table 1 lists preferred component values associated with regulation circuit 110 . The detailed working process of the regulating circuit 110 shown in FIG. 5C is obvious to those skilled in the art. To further enhance isolation from electrical noise sources, a reference voltage is applied to bandpass filter stages 142 and 144, amplifier stages 152 and 154, and rectifier 160 from a virtual ground (eg, a TLE2425 type virtual ground). The read head 86 is biased by a voltage regulator (eg, a LM7805 type 5 volt DC regulator in the pickup circuit 120).

Table 1 Component values of the signal conditioning circuit 110

R1-20KΩ C1-.01μF D1-1N914

R2-10KΩ C2-1.0μF IC1-LM324

R3-330KΩ C3-.10μF IC2-TLE2425

R4-75KΩ L1-300Mh IC3-LM7805

R5-10KΩ

R6-47KΩ

R7-27KΩ

R8-220Ω

R9-100KΩpot

R10-1MΩ

R11-100KΩ

The output signal 220 of the signal conditioning circuit 110 is sampled for each incremental advance of the timing wheel assembly 77 by the analog-to-digital converter 304 shown in FIG. signal shown in 5B), and digitize the sampled signal. The digital value thus obtained is accumulated by the CPU 302 during the detection time interval between times t2 and t4 when the document is detected by the photosensor. These digital values can be accumulated eg by summing the values obtained during detection. Alternatively, the accumulated value may represent the average of the sampled values, or represent a comparable statistical measure of the digital values obtained during the test period.

After the t4 detection interval has elapsed, the accumulated value is compared to one or more reference values to verify that the accumulated value corresponds to the value of a genuine document having predetermined or acceptable magnetic characteristics or properties. For example, the accumulated value may be compared to a reference value in the form of a lower threshold and an upper limit defining a range of acceptable accumulated values by which a security can be identified as acceptable. accepted or genuine securities. In the following, a procedure is described in more detail with reference to Figs. 7A-D, in which a verification check of the magnetic properties may be implemented in conjunction with other functions of the document processing apparatus.

It has been found that an advantageous method of verifying the authenticity of a document is to accumulate sampled values corresponding to the magnetic properties of the document and then compare a representative value with one or more reference values. This procedure is particularly beneficial when the documents being examined are sufficiently magnetic and/or have magnetic properties that are spatially distributed such that authentic documents can be reliably distinguished from suspected counterfeit documents. The magnetic ink portion of some securities to be inspected may be relatively localized and/or magnetically weak compared to U.S. currency. For example, as shown in FIG. 9, a fifty yuan banknote 350 issued by the People's Republic of China includes a relatively small area 352 in which there is relatively strong magnetic ink. The ink on the rest of the $50 note is rather weakly magnetic. An area 352 containing relatively magnetic ink is near the bottom center of the back of the $50 note 350 . The front side (not shown) of the $50 note 350 also includes a defined area where relatively magnetic ink is present. Additionally, the magnetic ink used on the $50 bill is less magnetic than the magnetic ink used on US currency. A net result of the reduced magnetic properties of the ink on the $50 bill is that the response given by the signal conditioning circuit 110 as described in connection with Figures 5A-C is lower than that obtained with US currency. Therefore, it is not possible to reliably distinguish the electrical signal resulting from detecting the magnetism of an authentic $50 note from the electrical noise detected as a counterfeit $50 note passes through the counting device.

In order to reliably verify documents such as $50 bills in terms of their magnetic properties, an enhanced magnetic detection and conditioning system with high gain and low sensitivity to circuit 110 noise is preferably used in the device. Figures 10A and 10B schematically illustrate such an enhanced detection and conditioning system, which includes read head 360 and conditioning circuitry 110a. In Table 2, preferred component values related to the regulation circuit 110a are listed.

Table 2 Component values of signal conditioning circuit 110a

R1-10KΩ C1-10μF D1-1N914

R2-10MΩ C2-.005μF D2-3.8V Zener

R3-500KΩpot. C3-.1μF IC1-LM324

R4-75KΩ IC2-MAX680

R5-150KΩ

R6-47KΩ

R7-100KΩ

R8-3KΩ

Read head 360 is mounted in the processing apparatus in the same manner as described in connection with read head 86 in FIG. 3A. Read head 360 is connected to a DC power supply as shown in FIG. 10B and provides a pickup signal on line 362 according to the passing state of the magnetic document. Read head 360 is preferably a magnetoresistive sensor, such as a Currency Identification Sensor made by MurataErie North America of Smyrna, Georgia, Model No. BS05NIHGAA. Read head 360 does not require an external magnetic field in the document guiding path as previously described in connection with permanent magnet 88 . Since a separate magnet (eg, magnet 88) is not required, the effect of relative vibration between read head 360 and such a magnet is eliminated.

In order to further reduce the influence of electrical noise, the installation position of the signal conditioning circuit 110 a in the device should be far away from the read head 360 and away from the motor 321 . The electrical signal applied to line 362 is applied via shielded cable 364 to signal conditioning circuitry 110a at the remote end of the device. The pickup signal from line 362 is capacitively coupled to conditioning circuit 110a and received by fixed gain amplifier 366 in the conditioning circuit. Amplifier 366 preferably comprises an LM324 operational amplifier connected to bipolar 10 volt DC power supply circuit 369 shown in FIG. 10B. The power supply circuit 368 preferably includes a charge pump converter, model MAX680DC/DC, manufactured by Maxim Integrated Products of Sunnyvale, California. The bipolar 10 volt supply is shown connected to amplifier 366, and to other components in signal conditioning circuit 110a, so compared to the comparator circuit in conditioning circuit 110 that uses a single-ended supply (as shown in FIG. 5A ), The amplifier 366 can provide a larger voltage change according to the pick-up signal. The bipolar DC power supply 369 is conveniently operated with a 5 volt DC signal which is compatible with logic circuits used elsewhere in the processing apparatus.

The amplified signal generated by the amplifier 366 based on the pickup signal is capacitively coupled to the input terminal of the variable gain amplifier 368 . Variable gain amplifier 368 preferably includes a potentiometer R3 for adjusting the gain of amplifier 368 to compensate for signals from documents having different magnetic properties. For example, potentiometer R3 may be adjusted so that amplifier 368 has a relatively low gain value for processing United States currency. In order to deal with Chinese currency or other securities with relatively weak magnetic characteristics, the potentiometer R3 can be adjusted to make the gain value quite high. Other means of adjusting the gain of amplifier 368 (eg, gain selection switch means) may be used in the practice of the present invention, providing the user with the ability to adapt signal conditioning circuit 110a to the magnetic characteristics of particular types of documents being processed.

The output signal of the variable gain amplifier 368 is applied to the input terminal of the high-pass filter 370, and the high-pass filter 370 removes frequency components lower than a predetermined frequency (eg, lower than 300 Hz) in the amplified signal. The filtered signal from filter 370 is capacitively coupled to a combined rectifier/integrator 372 . A rectifier/integrator 372 rectifies and integrates the filtered signal. The operation of rectifier/integrator 372 is similar to that of rectifier 160 and integrator 180 previously incorporated in circuit 110 .

Signals as high as 10 volts may be generated in the conditioning circuit 110a in response to unusually strong magnetic properties or in response to transient signals because several stages of the conditioning circuit 110a include operational amplifiers connected to a bipolar 10 volt supply. It is desirable to clip the conditioned signal generated by the signal conditioning circuit to a level below 10 volts so that the conditioned signal is compatible with the lower voltages used by logic circuits elsewhere in the device. To limit the voltage provided by output 376 of signal conditioning circuit 110a, a clipping circuit 374 is connected between rectifier/integrator 372 and output 376 to limit the rectified and integrated signal. The clipping circuit preferably includes a Zener diode D2 connected between output terminal 376 and ground. The Zener diode is chosen to limit the voltage available at output 376 to a level compatible with the reference level of the A/D converter receiving the conditioning signal from output 376, such as 3.8 volts or other desired Voltage value. A resistor R1 is connected in series between the rectifier/integrator and Zener diode D2 to limit the current flowing into diode D2 to an appropriate value.

Referring now to FIG. 11 , various voltage waveforms shown therein represent pickup signal 378 produced by read head 360 , filtered signal 380 produced by high pass filter 370 , and conditioning signal 382 received at output 376 . These signals are representative of the signals generated by a document (eg, a $50 bill) as it passes along the document-guiding path. For clarity, the noise components normally present in these waveforms are not drawn in the waveforms shown in FIG. 11 . Time t1 represents the time in the guiding path at which the leading edge of the document is detected by the central photodetector. At time t1, the pick-up signal 378 produced by the read head 360 temporarily changes slightly due to coupling of the head to the AC power source of the processing device. High pass filter 370 effectively blocks the 60 Hz frequency of the AC mains, so filtered signal 380 and conditioned signal 382 are substantially flat at time t1.

As the document continues along the guide path, portions of the magnetic ink pass the read head 360, causing the pickup signal 378 to generate several high frequency oscillations with an amplitude of approximately 200 μv peak-to-peak. This high frequency oscillation is amplified by amplifiers 366 and 368 and applied to a high pass filter 370, thereby producing a signal 380 having an oscillation amplitude of approximately 1 volt peak-to-peak. The oscillations of this signal 380 are then rectified and integrated to produce a continuous pulse of conditioning signal 382 having an amplitude of approximately 2 volts during the interval from time t2 to time t3. After time t3, the magnetic ink portion of the document has passed the read head 360, so waveforms 378, 380 and 382 have no apparent sustained pulses. At time t4, the trailing edge of the document passes the central photodetector, thus obtaining the document detection interval.

Documents may be inspected using signal conditioning circuit 110a in the manner described in connection with signal processing circuit 110 . Alternatively, circuit 110a may also be used in the practice of another method described below.

As can be seen from FIG. 11, the interval between time t2 and time t3, when the adjustment signal 382 has a continuous pulse period, is relatively short compared to the entire detection interval t1-t4 during which the photodetector detects the document. The relatively brief nature of the sustained pulse in conditioning signal 382 between time t2 and time t3 places an upper limit on the range of accumulated values that can be obtained by sampling this signal 382 and summing the sampled values during passage of true documents. This limited range of accumulated values again adversely affects the ability to reliably distinguish between genuine and counterfeit securities. Furthermore, the intervals of duration pulse amplitudes in the waveforms associated with the passing state of such securities are rather short, which makes the accumulation of samples more sensitive to the effects of spurious signals, which are relatively strong and/or large The magnetic ink portion of the security is concerned. For example, as shown in FIG. 11, for the pickup signal 382, a noise spike occurs at time t5 of the detection interval. The final pulse in conditioning signal 382 caused by the spike at time t5 may have a significant effect on the value of the cumulative sum of the sample values of waveform 382, which are used along the lower time axis of FIG. The sampling intervals indicated by multiple small vertical bars are obtained.

To overcome the aforementioned difficulties in inspecting documents with weak and/or highly confined magnetism, an alternative method of inspecting documents can be used in which counts are accumulated based on the transient nature of the conditioning signal 382 . In this way, successive sampling intervals in which the adjustment signal of the detection interval adjustment circuit 110a exceeds the predetermined lower threshold _VL are counted, thereby obtaining a count value (or an accumulated value). The accumulated counts are then compared to one or more reference values corresponding to genuine securities for the duration of the pulse portion of a conditioning signal.

This last method of checking documents preferably includes the step of counting and accumulating the sampling intervals in which the output signal of conditioning circuit 110a exceeds the upper limit _VH . In order to identify a count of a genuine document, the count of sampled values greater than _VH must be less than a predetermined maximum reference value and the count of successive sampled values greater than _VL must be greater than a predetermined minimum reference value. The manner in which this method is implemented and the manner in which it is combined with other functions of the document processing device is described below in conjunction with the logic flow diagram of FIG. 7E. control network

The operation of the counting and sorting equipment is monitored and controlled by the control network 301 shown in FIG. 6A. The microprocessor (eg, CPU 302) executes a control program stored in a non-volatile memory (eg, ROM 318). The control program coordinates the following functions: counting, sorting, security inspection, motor control, display control, user input, and communication with external devices. The CPU 302 is preferably a µPD78C10 manufactured by Nippon Electric Company. CPU 302 is connected to a random access memory RAM 319 which has a series of registers for storing and retrieving information during execution of the control program. RAM 319 can be an external RAM, or can be monolithic or integrated with the microprocessor. CPU 302 is connected to a multi-channel analog/digital (A/D) conversion circuit 304. In a preferred embodiment, A/D circuit 304 and CPU 302 are monolithically integrated. A/D circuit 304 receives analog signals from sensors 66, 64, 80, 82, 84 and magnetic signal conditioning circuit 110 and provides digital signals to CPU 302 corresponding to the respective analog signals.

Connect an LED control circuit 306 between CPU 302 and LED 83,85. The LED control circuit is a multi-channel digital-to-analog converter that adjusts the brightness of the LEDs according to the signal received from the CPU 302. The change in magnitude of the LED brightness is particularly important to the left and right sensor circuits 82, 84, since these circuits are used to determine the presence and obscuration of documents passing through the device. The luminance required for an obscuration test may be much greater than that required for detecting the presence of a document. Since the reliability of LEDs decreases with increasing brightness, it is desirable to operate the left and right LEDs at high brightness only when opacity data is required. The specific brightness required to determine the opacity of a document depends on the type of document being counted and sorted, so it is desirable to allow the user to specify the magnitude of the brightness used. The LED control circuit 306 also provides the CPU 302 with the ability to switch the LEDs to document detection brightness levels when the device is in a stopped state.

Keyboard interface circuit 308 is connected to CPU 302 and keyboard 14 to enable a user to specify or modify operating parameters during execution of a control program. Display interface 310 is connected to the CPU and drives display 16 which provides count and status information to the user. RS-232 type interface driver 314 is also connected to CPU 302, makes this counting and sorting equipment can interface with external equipment 316. External device 316 may be a general purpose computer. The computer is programmed to communicate with and control the device according to the serial communication protocol. Alternatively, the external device 316 can also be a printer, such as a thermal printer, for printing segment counts, denomination counts, and total amounts of securities counted by the device. The CPU 302 is programmed so that it can distinguish different types of external devices according to the wiring or jumper lines set on the serial interface of the external devices. External I/O via RS-232 type interface 314 may be used to supplement or replace user commands entered directly via keyboard 14 .

The motor control circuit 312 is connected to the CPU 302 and is used to provide programmed control of the motor 321. The motor control circuit can switch the motor on and off according to the signal from the CPU 302, or change the speed of the motor.

CPU 302 includes an interrupt input terminal INT, and input terminal INT is connected to timing wheel assembly 77 via interrupt line 79. A timing wheel assembly, shown schematically in FIG. 6B, provides timing signals to CPU 302 for coordinating the counting operation and the accumulation function of sensor data during conveyance of documents through the counting and sorting apparatus. The timing wheel 74 is mounted on the acceleration shaft 56, so the timing wheel 74 and the acceleration wheel 56 rotate synchronously.

As previously described, the LED 75 and light sensor 78 are positioned on opposite sides of the timing wheel 74 and are aligned so that the sensor bias circuit 76 generates a pulse when the wheel 74 rotates, the timing of which occurs and each The time between each radial opening passing through the LED 75 and the sensor 78 is the same. The output of sensor bias circuit 76 is sent to the interrupt port of CPU 302 through interrupt line 79. The number of radial openings in the timing wheel 74 is preferably such that a document passing between the accelerator wheels 52,54 will generate approximately 66 interrupt pulses. In terms of distance, approximately every millimeter of peripheral rotation of the timing wheel assembly relative to the accelerator wheel 52 will generate an interrupt pulse.

A preferred control routine for controlling the operation of the apparatus is shown in the flowcharts of Figures 7A-7D. The control program includes the following functions: command I/O, sensor data accumulation, sensor data evaluation, and document counting. Referring now to FIG. 7A, an initial step 224 is performed to determine the mode of operation and configuration of the device. In step 224, the CPU determines whether an external device has been connected via the RS-232 type interface. If an external device is detected, the RS-232 line is checked to determine if a jumper is present, i.e., if the external device is a computer interacting with the CPU 302, or if the external device is a printer from which the CPU 302 only sends output. It should be noted that if it is determined at 224 that such an external device connected in the system has been detected, then this specified reference to user input via the keyboard and output via the display can also be used for input and output from the external device. Output to external equipment.

In step 226 related to start selection, inputs such as denomination of securities to be counted, selection of sorting or counting methods, batch size, speed of operation, selection of inspection methods, etc. are entered into the control process. The user may also cycle through the display loop at step 226 to obtain a display of the accumulated segment count, denomination count and/or total. The accumulated counts and/or totals can optionally be printed on a printer or added to a host if the device has been connected to such an external device via an RS-232 port. By requesting display of the accumulated count and/or total, the accumulated count and/or total may be modified in accordance with a running count. The running count is in a register that stores the number of securities counted since the most recent display request. Run count reset after each total display request. Whenever a total amount count is requested, the CPU 302 calculates the total amount value from the individual denomination counts which may be stored in RAM 319 or stored in internal CPU registers.

In step 226 several thresholds for error detection are also selected by user input or data previously stored in ROM. During step 226 the user may also select the amount of security for the security. The size of the selected shading determines the brightness of the left and right LEDs 83, 85 during the shading test. At step 226, the user may or may not allow the magnetic detection operation and/or the opacity evaluation operation on the suspected counterfeit note. If suspected counterfeit detection (CFS) is selected, the threshold for comparing magnetic data is selected by the CPU at a prescribed operating speed. Such selection must be made in accordance with the magnitude of the electrical signal generated by the read head 86 at the speed at which the document passes and approaches the read head 86 . In a preferred embodiment, the user can select between a high operating speed (approximately 1200 securities/minute) and a low operating speed (approximately 600 securities/minute). A low-speed option is provided to allow the user to visually determine the presence of suspected counterfeit securities by observing the securities as they are counted. This visual method of determining suspected counterfeit documents can supplement or replace the magnetic method of determining counterfeit documents. A document counting rate of around 600 documents/minute has been found to be low enough to allow visual inspection of documents.

The activation selection can be entered via an RS-232 type interface, or manually entered via the keypad 14 shown in detail in FIG. 8 . The keyboard 14 includes a plurality of switches through which the user can enter commands and selections as described in connection with step 226 of the control process. Keypad 14 includes a number of keys labeled: Start/Stop, Continue, Sorting, Denomination Select, Denomination Total, Total Amount, Clear Total, Speed, Suspect Detection, and Double Detection. The Start/Stop key is a momentary switch that is pressed to start and stop operation of the device. The resume key is a momentary switch used to restart counting and sorting equipment after an interruption in operation. Operation of the continuation key provides a signal to the counting and sorting equipment to restart operation and continue the current count after detection and removal of suspected counterfeit notes or after operation of the start/stop key. The denomination selection key is used during step 226 of the control process that cycles through the tables and menus to select the denomination of banknotes to be counted in a particular operation, or to specify a segmented count regardless of denomination size. Use the denomination total key to display the cumulative total or total segment count for each denomination being counted. Press the Total Amount key to display the sum of the accumulated amounts for each denomination. The Clear Total key resets the displayed cumulative total to zero. If the clear total key is operated while the total amount is displayed, all denomination totals are reset.

A suspect counterfeit detection (CFS) key is used during step 226 to turn magnetic detection of suspect counterfeit documents "on" or "off". In step 226, double check key is used to select the size of LED brightness for shading test, or prohibit shading test. In step 226 the speed key is used to select between high and low operating speeds. In 226 steps, select the sorting operation and the size of the horse quantity with the sorting key. When the selection of start parameters is completed at step 226, the motor is started, and the control process proceeds to step 228 when the start key is pressed.

At step 228, several variables related to security testing are set to zero. As each document passes through the apparatus, the length of the document is measured by counting the timing pulses generated by the central sensor 80 to detect the presence of each document. If an unusually large number of timing pulses are counted while the central sensor is covered (which also indicates the presence of documents), the counting and sorting apparatus is stopped. At step 228 the two counts (length count and idle count) are reset through each bond period. At step 228 the two flags (right sensor flag and left sensor flag) used to check documents for width deviations are also reset.

Program advances to 230 steps from 228 steps, is used for the reset of several registers of RAM 319 of accumulated securities inspection data. During each document pass, the total number of operations on the left and right sensor signals, the output of the magnetic signal conditioning circuit, and the number of interrupt pulses detected are accumulated in corresponding registers in RAM 319. At step 230, the totals stored in these registers during each security pass are reset.

The program proceeds from step 230 to step 232 to detect the presence of the document according to the value corresponding to the central sensor 80 about the A/D channel. If the central sensor signal value is below the predetermined detection threshold, control branches to step 234 to wait for an interrupt pulse from the timing wheel. When an interrupt pulse is received at step 234, control proceeds to step 236 where the idle count is incremented. Then, at step 238, the idle count is compared to a predetermined limit. If the idle count does not exceed the limit at 238 steps, then control returns to 232 steps. If at 238 steps the idle count has indeed exceeded the idle limit, then control proceeds to 268, which stops the device from operating, and then proceeds to 270, where control continues to wait for the input. Beginning at step 270, the control process may branch to step 226 when a command to continue to start is received, or to step 228 when securities placed in the hopper are detected. In general, the control path from step 270 depends on the state conditions leading to step 270 and the nature of the action taken by the user, or input by an external device.

If at step 232 the central security sensor does register the presence of a security, then control proceeds to step 233 of FIG. 7B (indicated by continuation mark B). At step 233, two conditions are checked to determine if the motor should be stopped. The first condition is whether the stack count has reached a value representing an entire stack of boxes with less than one security. Due to the high speed at which the equipment operates, it is impossible for the security transfer mechanism to stop immediately. Therefore, if the stacker is to be full, such a determination must be made when the leading edge of each security is detected. Similarly, if the apparatus is operating in batches, then at step 233 it is determined whether the document currently being detected by the central sensor is the last document in the batch. If one of these two conditions is met, control proceeds to step 235 where the motor control circuit begins shutting down the motor using known braking techniques. When the motor control circuit starts to brake the motor, or when the conditions in step 233 are not satisfied, the control process advances to step 240 .

Step 240 is the first step in the data accumulation loop 200, during which an operational sum of sensor data is generated for each document as it passes the device.

When an interrupt pulse is detected at step 240, control goes to step 242 where the document length count is incremented. The control process goes from step 242 to step 244. At step 244, the flag of the right sensor indicating that a document has been detected previously is checked. During the first iterative operation of the data accumulation loop 200, the right flag has not been set and control proceeds to step 246. At step 246, the A/D channel corresponding to the right sensor signal is queried to determine the presence of documents along the right side of the lower guide plate 50. If a document is detected, then control proceeds to step 248, the right sensor flag is set at 248, and the brightness of the right LED is determined by the LED control circuit 306 according to the opacity selected at step 226, and control proceeds to 252 steps. If no securities are detected along the right side of the lower guide plate 50 at 246 steps, then the control process directly advances to step 252, and the right LED still remains at the brightness of the securities detection. If either the left sensor flag or the right sensor flag is not set during the security data accumulation cycle 200, a width deviation detection of the security occurs. Once the right sensor flag is set at step 248, the subsequent execution of step 244 branches control to step 250. In step 250, the corresponding A/D channel of the right sensor is sampled and accumulated in a register of RAM 319, and the control process goes to step 252. The variation range of the shading data taken by the A/D converter from the right sensor at 250 steps is generally quite small. In order to clearly delineate normal securities and securities with more shading (such as a double-layer security), it is best to roughly quantify the shading data into several broad ranges, and numerically weight these ranges to reduce small The effect of range shading changes. Quantification using only Level 4 opacity data is sufficient to complete the discrimination between single and dual securities.

Beginning at step 252, a determination step is performed for the left security detector similar to that performed for the right detector in steps 244-250. If at step 252 it is found that the left flag has been set, then control goes to step 258 where the magnitude of the signal from the left sensor is measured, quantified and accumulated. If at 252 it is found that the left flag is not set, then control proceeds to 254 steps. At step 254, the left sensor is sampled and compared to a threshold to determine if there is a document to the left of the deflector. If a security is detected at step 254, control proceeds to step 256 to set the left flag. In 256 steps CPU 302 also will send a signal to LED control circuit 306, so that the brightness of left LED 83 is improved to the level of the selected shading property detection in 226 steps. The control process is transferred from step 256 to step 260. If no security is detected at the left light sensor at step 254, then control goes directly to step 260.

At step 260, the A/D channel corresponding to the output of the magnetic signal conditioning circuit 110 is sampled and accumulated. Control then passes to step 262 where the central sensor's A/D channel is sampled again to determine the presence of the document. If the central detector also detects a security, then control returns to step 240 and the data accumulation loop 200 continues. When a document is not detected at step 262, the data accumulation loop 200 ends and control branches to step 263 to begin the data evaluation phase of the control process shown in FIG.

Starting from step 263, the first test in a series of tests is performed according to the data accumulated during the data accumulation period. It should be noted that, besides the procedure shown in FIG. 7B, the data evaluation check can be performed according to other logic procedures. At step 263, the length count reached during the data accumulation cycle 200 is compared to the length threshold. If the length value is less than the threshold, then control proceeds to step 265 where a "half" error is displayed to the user via display 16. From step 278, control proceeds to step 267 shown in Fig. 7D as shown in continuation mark D2, resets the run count; then proceeds to step 269 to stop the motor. Then at step 271, control waits for a signal from the stacker photosensor that the document has been emptied from the stacker. If the length count exceeds the lower threshold at step 263 of Figure 7C, then control proceeds to step 264.

At step 264, the length count taken during the data accumulation cycle 200 is compared to an upper length limit value. If the length count exceeds the length upper limit value, then the information indicating the sticking error is displayed by the display, and/or the information is output to the RS-232 port in step 266 . From step 266, control proceeds to step 267 shown in Fig. 7D as indicated by continuation mark D2, at which the operation count is reset. Then advance to step 269 to stop the motor. Then at step 271, the control program waits for a signal from the stacker photosensor that the document has been emptied from the stacker. If the length count does not exceed the length upper limit at step 264 of FIG. 7C, then the control process proceeds to step 272 where the length threshold and the upper limit are modified according to a predetermined adaptability factor. Preferably, the upper and lower length limits are adjusted for each security to group together the most recently measured lengths of the security in a predetermined proportion. This proportional adaptability of the upper and lower length limits allows the device to continuously adapt to changes in motor speed as well as small changes in the length of the document.

After the document length limit has been modified at step 272, the accumulated magnetic data is divided by the length count to produce an averaged magnetic test value at step 274. The evaluation procedure then proceeds to step 276 where the right flag is checked. If the right flag is not set during the data accumulation loop 200, the program proceeds to step 278 where the document width deviation error is notified to the user by an appropriate display. From step 278, the control process goes to step 267 of Fig. 7D as indicated by continuation mark D2, where the run count is reset, and then goes to step 269, where the motor is stopped. Then at step 271, control waits for a signal from the stacker light sensor indicating that the stacker has been emptied of documents. If the right flag is found to be set at step 276 of Figure 7C, then the program begins checking the left flag at step 280, with similar results if the left flag is found not to be set. If the left flag is set, control proceeds to step 282.

At step 282, the contents of the left and right opacity data accumulation registers are compared with their corresponding threshold values determined at step 226. If the count in each occlusion data accumulation register exceeds the corresponding threshold, then at step 284 the user is notified that an error exists, such as a double error. From step 284, control proceeds to step 267 of Fig. 7D as indicated by continuation symbol D2, where the run count is reset, and then to step 269, where the motor is stopped. Then at step 271, control waits for a signal from the stacker light sensor indicating that the documents have been emptied from the stacker. If at step 282 of FIG. 7C, the count associated with the register accumulating opacity data is less than the corresponding threshold, or if double detection is disabled at step 226, then control proceeds to step 286 of FIG. 7D as indicated by continuation mark D1.

At step 286, the evaluation routine determines whether a suspected counterfeit check (CFS) is permitted. If CFS detection is enabled, control proceeds to step 288. At step 288, the magnetic inspection average determined at step 274 is compared to a predetermined threshold. If the magnetic inspection average value is not greater than the predetermined threshold, then in step 290, the user is provided with a suspected counterfeit note error display, and the motor is stopped. Since the document conveying mechanism cannot stop immediately, the suspected counterfeit document and the next document (if any) in the input stack are delivered to the stacking box when the motor is stopped at 290 steps. The control process then goes to step 291. In step 291, the suspected counterfeit coupon and the next security are taken out from the stacking box, the next security is put back into the hopper, and the continuation key is pressed, thereby resuming normal operation. After pressing the continuation key at step 291, the control process returns to step 228 of Fig. 7A as shown in continuation mark A, thus bypassing the counting operation to the suspected counterfeit note or the subsequent note delivered to the stacking plate.

If at step 286 it is found that CFS detection is disabled, or if at step 288 the CFS threshold is found to be exceeded, then control proceeds to step 292 .

At step 292, the run count and stack count are incremented by one. Use the stack count to ensure that the stack box capacity is not exceeded. Once the stacked document is removed from the stack box, the stack count is reset. The run count is the number of documents that have been detected since the most recent execution of step 226 of Figure 7A.

When advancing to 294 steps from 292 steps, if this equipment is set to operate by sorting mode, then branch to 296 steps. If at step 296 the security count has reached the specified batch size, then at step 298 the user is provided with an indication that a batch is complete. Because the batch of documents has been detected at step 233 to be complete before step 298 is reached, the motor has slowed down sufficiently so that the current document is the last document delivered to the stack. Control proceeds from step 298 to step 271 and waits for the batch of securities to be emptied from the stack.

If at 294 steps the equipment is not determined to be operating in sorting mode, or if at 296 steps the completion of the batch is not detected, then control proceeds to step 295 where the stacking count is checked at 295 to determine whether the stacking board is filled. full to its capacity. If it is determined at step 295 that the stacked board is not full, then control returns to step 298 to prepare for the next security accumulation data. If the stack is full, control passes to step 297 to give an appropriate indication that the stack is full. Control passes from step 297 to step 271 and waits for securities to be emptied from the stacker.

Step 271 is reached once a batch has been completed, the stacker is full, or an error other than suspected counterfeit has been detected. During step 271, the user (or the controlling host) is notified of the status of the device. In order to clear this error or otherwise restore the count, the document must be removed from the stack. Detecting other errors will also introduce uncertainty in the count compared to detecting suspected counterfeit documents. For example, if 271 steps are reached due to a double error, the operator cannot determine whether two or three securities should be removed from the hopper in order to resume normal operation. Double errors may be caused by passing two securities at the same time, or by passing a securities with abnormal opacity. To avoid destroying the integrity of the accumulated counts and totals, detection of errors other than spurious errors will reset the run count and remove all documents from the stacked deck (at step 271) and cause them to either return to Bucket, or termination count. Similarly, the other two conditions leading to step 271 (a batch completed, or a full stack completed) also require removal of all securities from the stack. When the stacker light sensor indicates that the document has been removed from the stacker board, operation resumes and control goes to step 273 .

Step 273 is a process to ensure that the security count is not in the "hidden security" condition. The hidden note is the last note in the hopper that was added from the hopper to the stacker during the motor stop operation prior to step 271, rather than delivered to the stacker. Since the operator cannot see such a document and there are no other securities remaining in the bin, a check is made at 273 to determine whether the bin is empty as determined by the bin light sensor. If the hopper is empty, restart the motor and let the motor run for an empty pause time to provide hidden stock to the stacked carton boards. Then, at step 275, since all documents have been removed from the stack, the stack count is reset and control returns to step 226.

The aforementioned portion of the control process for detecting suspect counterfeit documents can be modified to implement an alternative method of detecting counterfeit suspect documents that was mentioned in connection with the discussion of signal conditioning circuit 110a. In a modified version of the control process implementing the alternative method, the CPU accumulates: (i) a first count of successive sampled values of the magnetic detection adjustment signal exceeding a first predetermined reference value; and (ii) exceeding a second predetermined reference value The second count of sampled values for values. Each of the first and second accumulated counts is compared to one or more reference values associated with genuine documents to verify each document. Specifically, the alternative process utilizes a count register that counts up and a flag register that indicates whether the document has passed or failed the inspection comparison. These registers are initially cleared to zero at steps 228 and 230 of the control process prior to the test interval.

In this alternative document inspection method, step 260 of the control process of FIG. 7B is replaced by a process shown in FIG. 7E and designated as 260a.

Referring now to FIG. 7E, at step 400 the controller operates the A/D converter to obtain samples of the conditioning signal from conditioning circuit 110a. Then, at step 402, the controller compares the sampled value obtained at step 400 with a predetermined reference value V _L representing a minimum threshold. If the sampled value does not exceed V _L , control branches to step 418 where the counter register for counting successive sampled values greater than V _L is reset. The controller then proceeds to step 414, which will be described later.

If it is determined at step 402 that the sampled value is greater than V _L , the controller proceeds to step 404 . At step 404, the count register used to hold the count of successive samples greater than V _L is incremented. Such registers are referred to below as "low count" registers. Then, the controller proceeds to step 406.

At step 406, the value contained in the low count register is compared to a _{predetermined reference value corresponding to the minimum number of corresponding samples above VL required} to verify that a document is authentic. If the accumulated value of the low count register exceeds the predetermined reference value, then the control process advances to step 408, and the flag register is set at 408 steps, thereby indicating that: the necessary minimum count value has been exceeded, and with respect to the value of the low count register The security has passed the verification test. The controller then proceeds to step 410 .

If at step 406 the value of the low count register does not exceed the necessary minimum value, then the controller proceeds to step 410 .

At step 410, the sampled value obtained at step 400 is compared to a predetermined limit value V _H . If the sampled value is found to be greater than V _H , the controller proceeds to step 412 to increment another register ("high count" register). The controller then goes to step 414 .

If it is found at step 410 that the sampled value is not greater than V _H , the controller proceeds to step 414 .

At step 414, the value accumulated in the high count register is compared to a predetermined reference value or maximum value, and securities above this reference value are identified as suspected counterfeit documents. If it is determined: the content of the high count register is greater than the predetermined maximum value, then the controller proceeds to step 416 to set the pass flag register, which indicates a suspected counterfeit note. The controller then proceeds to step 262 (see the control process shown in FIG. 7B). If at step 414 the value accumulated in the high count register does not exceed the predetermined maximum value, then the controller steps from 414 to step 262 of Figure 7B and continues program execution as previously described.

As can be seen from the process shown in Figure 7E, a successful verification of an actual security is indicated by the flags register. If the pass flag register is not set, such a condition indicates that the security is a suspected counterfeit. If a few consecutive sampled values during document detection are greater than the lower threshold V _L , or a predetermined number of sampled values are greater than the upper limit V _H , this indicates that the document is counterfeit. It is worth noting that these two criteria can be implemented in combination as described here, but either of the two test criteria can be used individually if desired.

It should be noted in the practice of this alternative document inspection method that the counterfeit document detection step 288 described in connection with FIG. 7D can be modified so that its main function is to determine whether the passing flag represents a detection result of a suspected counterfeit document.

From the foregoing disclosure and accompanying drawings, the present invention provides certain novel and useful features which should be apparent to those of ordinary skill in the relevant arts. In particular, an improved document counting and sorting apparatus is described in which optical and magnetic verification checks are performed with programmable digital thresholds of the sensor signal and by reducing the impact of electrical noise on the sensor signal. effect improves reliability.

The terms and expressions used are for the purpose of description only and not of limitation. It is not intended that the use of these terms and expressions exclude equivalents of the features and components (or portions thereof) shown and described herein. Various modifications are possible within the scope and concept of the claim.

Claims (20)

1. a check has the equipment of authenticity of the security of magnetic, comprising:

A security guide path is used for guiding security at this equipment;

A Magnetic Sensor of installing along the security guide path is used to detect the magnetic of the security that move along said security guide path, and when said Magnetic Sensor detected the magnetic of security, said Magnetic Sensor produced a sensor signal of representing security magnetic;

Digital switching device, response produce the representational digital value of representative sensor signal from the signal of Magnetic Sensor;

Adding up device is used for producing an accumulated value according to the digital value from digital switching device; And

Comparison means responds said accumulated value so that the predetermined value of said accumulated value with the magnetic of the true security of representative compared, and can determine to have the security of acceptable magnetic thus.

2. equipment as claimed in claim 1, wherein said adding up device comprises first counting assembly, is used to provide the counting of one first accumulated value as the digital value that surpasses first pre-determined reference value.

3. equipment as claimed in claim 2, wherein said adding up device comprises second counting assembly, is used to provide the counting of one second accumulated value as the digital value that surpasses one second pre-determined reference value.

4. equipment as claimed in claim 3, wherein said comparison means comprises:

First comparison means is used for more said first accumulated value and first pre-determined reference value, and this first pre-determined reference value is relevant with the security with true magnetic characteristic:

Second comparison means is used for more said second accumulated value and second pre-determined reference value, and this second pre-determined reference value is relevant with the security with true magnetic; And

Indicating device responds said first and second comparison means, is used to indicate whether these security are suspicious pseudo-certificate.

5. equipment as claimed in claim 1, wherein said comparison means comprises the device of more said accumulated value and at least two predetermined values, these two predetermined values have been determined a predetermined scope of the value of the true security of representative.

6. equipment as claimed in claim 1 wherein further comprises the magnetizing assembly that is used to magnetize security.

7. equipment as claimed in claim 6, wherein said magnetizing assembly and said Magnetic Sensor are installed rigidly.

8. equipment as claimed in claim 1 wherein further comprises a circuit for signal conditioning, and this circuit responds said sensor signal and provides a conditioning signal to digital switching device.

9. equipment as claimed in claim 8, wherein said circuit for signal conditioning comprises an integrator, the said signal that is used to respond from Magnetic Sensor produces an integrated signal.

10. equipment as claimed in claim 8, wherein said circuit for signal conditioning comprises:

An amplifier is used to amplify from the said signal of Magnetic Sensor and produces one first amplifying signal, and

A wave filter is to the said first amplifying signal filtering and produce a filtering signal.

11. as the equipment of claim 10, wherein said circuit for signal conditioning further comprises:

A fairing is used for said first amplifying signal of rectification and provides a rectified signal to said wave filter; And

Amplitude limiter connects said wave filter and said digital switching device, is used for amplitude peak with said filtering signal and is restricted to a level with said digital switching device compatibility.

12. equipment as claimed in claim 1 wherein further comprises restraint device, be used for the security guide path constrain in said Magnetic Sensor near, therefore can detect magnetic equably by any security of said Magnetic Sensor.

13. as the equipment of claim 12, wherein said restraint device comprises rotating a wheel.

14. a check has the method for authenticity of the security of magnetic, comprises the steps:

Transmit security along a guide path;

During said transmission, detect the magnetic of security;

Produce the detection signal of a representative in the said magnetic of the security of said detection step detection;

To said detection signal sampling and generation sampling value;

The sampling value that adds up is so that produce an accumulated value at least;

The predetermined value of more said accumulated value and the true security magnetic of representative can be determined the security with acceptable magnetic thus.

15., wherein further comprise the step that before said accumulation step, detection signal is limited in a predetermined maximum level as the method for claim 14.

16. as the method for claim 14, wherein said accumulation step comprises that the said accumulated value that adds up is as said sampling value sum.

17. as the method for claim 14, wherein said accumulated value step comprises the counting of one first accumulated value as the said sampling value that surpasses a predetermined threshold that add up.

18. as the method for claim 17, wherein said accumulation step comprises the counting of said first accumulated value as the sampling value in succession that surpasses said predetermined threshold that add up.

19. as the method for claim 18, wherein said accumulation step comprises the counting of one second accumulated value as the sampling value that surpasses a preset limit value that add up.

20. as the method for claim 19, wherein said comparison step comprises:

More said first accumulated value and one and the relevant predetermined minimum value of security with true magnetic;

More said second accumulated value and one and the relevant predetermined maximum of security with true magnetic; And

Show that according to relatively result magnetic values that security are in it represents the time in the state of true security.

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