GB1579390A - Currency-note validation apparatus - Google Patents

Description

(54) IMPROVED CURRENCY-NOTE VALIDATION APPARATUS (71) We, FORECOURT AUTOMATION LIMITED, a British company of Pennygillam Industrial Estate, Launceston, Cornwall, PL15 7EB., do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement This invention relates to currency-note validation apparatus, arranged to determine by photo-electric inspection whether a currency note proffered to a vending mechanism is valid, and if so to accept the note and establish a corresponding credit.

According to thte present invention there is provided currency note identification apparatus including means arranged to guide a currency note along a predetermined path, means for illuminating respective portions of a currency note when said note is disposed at a predetermined position in said path, a plurality of photosensitive means arranged to yield individual signals denotive of optical characteristics of said respective portions of said note, individual comparators each arranged to compare a respective one of a first plurality of said individual signals with two respective reference levels and to develop an enabling signal only when the respective said individual signal has a value between the respective said reference levels, means arranged to develop an inhibiting signal except when all of said comparators yield respective said enabling signals, and logic means arranged to provide a credit denotive signal only when said inhibiting signal is absent at a time when a further plurality of said individual signals attain respective values denoting that said note is in said predetermined position.

Preferred features and advantages of the invention will become apparent from the following description of an nembodi- ment thereof given with reference to the accompanying drawings, of which: Figure 1 is a diagram showing amplifier arrangements for photo-diodes used in examining a proferred note; Figure 2 is a diagram showing the circuit arrangement of one of a plurality of twin threshold amplifiers used in the apparatus; Figure 3 comprises diagrams showing connections by which signals received from photo-diodes are applied to the twin threshold amplifiers of Figure 2; Figure 4 shows arrangements of amplifier and logic circuits included in the apparatus; Figure 5 illustrates further amplifiers and logic circuits included in the apparatus; Figure 6 shows power supply and relay circuits included in the apparatus; and Figure 7 is a schematic representation of a mechanism embodying the invention.

Reference is first made to Figure 7 of the drawings, which shows schematically a note acceptance mechanism 3 embodying the present invention.

The mechanism 300 includes a first guide member 301 bounding one side of a note insertion channel and carrying an array of sixteen photo-diodes PD1 to PD11, which are individually positioned to receive, from a respective one of an array of light sources LS, to LS, carried 'by a second guide member 302 bounding the other side of the note-insertion channel, light which has passed through, or in some cases has been reflected from a note 303 (shown in broken-line outline only) inserted in the channel, as the note is advanced along the channel towards a first pair of rollers 304. The positions and functions of the respective photo-diodes will become appa rent from the following description of the apparatus.

Signals from the photo-diodes of array 301 are fed to a processing system 305 in which they are processed to determine whether or not the proferred- note is valid and when validity is found, to produce a signal causing a motor 306 to be energised to drive rollers 304 through drive means indicated only by a broken line 306a, and thus to draw the note into the apparatus. In its path following rollers 304 the note encounters a flap 307 pivoted about a horizontal axis 307a. The flap is raised by the note and when so raised interrupts a light path LP along which light otherwise passes from a light source LS17 to a photo-diode PD17. The leading end of the note is then engaged by a second pair of rollers 308, also driven by motor 306, and thus continues to advance.When the trailing end of the note releases flap 307 the flaps falls and the light path between light source LS17 and photo-diode PD17 is restored. The resulting signal initiates a credit signal which is fed out over a signal channel 309 to permit the supply of goods.

As has been indicated above, the validity of the note is examined by an array of sixteen photo-diodes, PD1 to PD16, while an additional photo-diode Pud17 is used to check the attitude of a flap that is mechanically displaced by the note in its movement into the apparatus. As shown in Figure 1, all of these photo-diodes are connected to individual pre-amplifiers 121, 121, 127 12it, 1216, 1217. A common reference voltage for the head amplifiers is provided by a Zener diode 9 fed by way of a resistor 8 from a general positive supply for the apparatus.

As shown in Figure 7, each of the photodiodes is arranged to receive light from an individual light source LS1-LS17, conveniently consisting of an under-run incandescent bulb.

The amplified photo-diode signals appearing at the output terminals 13l-13l7 of the respective pre-amplifiers are all further amplified before being applied to the logic circuitry 'by which acceptance or rejection of a note is effected. The signals derived from terminals 131, 132, 135, 139, 1316 and 1317 are amplified in respective invidiual amplifiers 76, 74, 72, 73, 71 and 75 (Figure 4A), while that from terminal 135 is applied to an amplifier 111 (Figure 5).

As described below in relation to Figures 2 and 3, the individual signals from a plureality of the light-sensitive means constituted in this embodiment by photo-diodes 136, 134, 136, 131o and 13it, are applied to respective comparator means arranged to yield an enabling output signal only when the respective individual signals are between respective predetermined reference levels. In addition, signals from a further plurality of the light-sensitive means, specifically photo-diodes 137, 13it, 13it, 1314, 1315 and 1316 are also applied in combination to similar comparator means as will now be described.The enumerated photodiodes are all connected to twin threshold amplifiers 501-506, each arranged to yield a zero output only when the respective signals are predeterminedly related to at least one reference level, that is, when the illumination of a respective photocell is within predetermined limits. The outputs of all the twin amplifiers 501-506 are combined at a terminal 60 to yield an enabling (zero) signal only when the illuminations of all of the photo-diodes are within respective preset limits.

The construction of one twin threshold amplifier 50 is shown in Figure 2. Signals received at an input terminal A are applied to the inverting input of an amplifier 51, the non-inverting input of which is supplied with a preset reference potential from a potentiometer 52 connected across the operating supply. Signals received at terminal B are applied to the non-inverting input of an amplifier 55, the inverting input of which receives a preset reference voltage from a potentiometer 56.

The output of amplifier 51 is connected to an output terminal 60 by way of a diode 53 and that of amplifier 55 is connected to the same output terminal 60 by way of a diode 57. Thus output terminal 60 will be held positive unless the signal applied to terminal A exceeds the reference potential set by potentiometer 52 and un less the signal applied to terminal B is less than the reference potential set by potentiometer 56.

The connections of the photo-diodes to respective twin threshold amplifiers are shown in the diagrams given as Figures 3a-g. Diagram 3a shows that output terminal 138 of pre-amplifier 123, to which the signal developed by photo-diode PDn is applied, is fed to both terminals A and B of twin amplifier 501. Thus a positive potential will be applied to the output terminal of this twin amplifier unless the signal applied to its inputs lies between the limits set by the two potentiometers. Diagrams 3b, 3d, 3e and 3g show that the signals derived from photo-diodes PPD4, PD6, PD17 and PD;2 are treated exactly similarly, though the respective amplitude limits will be individual to the photodiodes.

Diagram 3c indicates that the signal from PD7 that receives light reflected from a portion of the note; is applied to terminal A of amplifier 503 while terminal B of this amplifier is connected to photo-diode PD16 .that receives light transmitted through the corresponding part of the note. A diode 61 is connected between terminals A and B so as to conduct if terminal B is more positive than terminal A. This arrangement assures that an output signal will be given at terminal 60 which is common to all the amplifiers unless the signal received from photo-diode PD7 is greater than the value set by the LOW potentiometer and unless the signal provided by photo-diode PD11 is lower than the value set by the HIGH potentiometer and greater than the value set by the LOW potentiometer.

Diagram 3f indicates that the signal from PD15 that receives light transmitted through a part of the note, is connected to input terminal A of double-threshold amplifier 50f, the signal from photo-diode ii, that receives light reflected from the same part of the note is connected to input terminal B of the amplifier and the two input terminals are connected by a diode 62 poled to conduct if terminal A becomes more positive than terminal B.

This arrangement ensures that an output signal will be given at the common output terminal 60 unless the signal received from Pud16 is above the limit set by the LOW potentiometer in that amplifier and below that set by the HIGH potentiometer, while the signal from photo-diode 11 must be below the limit set by the HIGH potentiometer and above the limit set by the LOW potentiometer.

Diagram 3h indicates that photo-diodes 13 and 14, which respectively receive transmitted and reflected light, are connected to amplifier 50h so that an output signal will be given at common output terminal 60 unless the signal from photo-diode 13 is within the limits set by the LOW and HIGH potentiometers and the signal from photo-diode 14 is above the LOW limit.

Each amplifier may have connected to its output a photo-diode, arranged to indicate that the respective amplifier is yielding an output that is useful during he setting up operation.

The circuit diagram given in Figure 4 shows amplifiers and a part of the logic circuitry. Amplifiers 71 to 77 are fed respectively with the signals from the pre- amplifiers associated with photo-diodes 5, 6, 9, 2 17, 1 and 16.

Amplifier 72 provides an amplified signal derived from Pud6 'by way of a terminal 81 to the logic circuits of Figure 5 and also, over a lead B and by way of a gate 95 to set a timer 96 and to a gate 92 to establish a setting path over lead D for a bistable trigger 93. The output of amplifier 73, which amplifies the signal received from photo-diode 9,, provides a signal that is applied by way of a diode 98 to an OR line 97 and thus to the inverting input of an amplifier 78 that in' turin feeds a signal over a lead C to the non-inverting input of a further amplifier 79 (Figure 4B) that assists in producing a WINDOW output that appears at a terminal W, as will further be described below.

The output of amplifier 74, which amplifies the signal received from photodiode 2, is applied by way of a diode 99 and OR line 97 to amplifier 78. Amplifier 75 receives the signal from PD,7 denoting the attitude of flap 307 and the amplified signal is fed to the main logic circuits (Figures SA, SB) by way of terminal 82 and is also applied to the inverting input of an amplifier 80, from the output of which it is applied through a diode 100 to OR line 97. The signal appearing on OR line 97 also depends upon the signal received from the common output terminal 60 of the twin threshold amplifiers 50 of Figure 2.

Initiation of the acceptance process is effected when PD9 senses the leading edge of the note. The output signal of amplifier 73 is inverted in an inverter 91, the output of which is applied to gate 92, that also receives the signal developed by PD6 and amplified by amplifier 72. The output signal of gate 92 is fed over a lead D to remove an inhibit signal from a latch 93 (Figure 4B). A signal derived from PD1 in response to the metal strip in the note appears at terminal 131 and is amplified by amplifiers 76 and 77, whence the amplified signal is fed over a lead E to set the latch 93, thus removing an inhibit signal that is applied from this latch, in the reset condition, to the logic circuitry of Figures SA and SB by way of a diode 94 and a terminal W.

The signal developed by amplifier 72 in response to a signal from PD6 is also applied by way of a lead B and an inverting gate 95 to initiate the action of a timer device 96, and thus to remove from terminal W a signal tha totherwise inhibits the operation of the logic circuitry. At the end of a period of some 6 to 8 seconds the timer re-applies the inhibiting signal to terminal W. If acceptance of a note has not been effected within this time limit (possibly because of movement of a forged note in an endeavour to determine an acceptable position) the acceptance process it terminated.

Photo-diodes, PD1 and PDg check the width of the proffered note. If either does not respond to the presence, of the note,, a positive potential will appear at the output of the respective amplifier 73 or 74 so that the common OR line 97 will be held positive by way of a respective diode 98 or 99. OR lirie 97 is connected to the inverting input of an amplifier 78, the output signal 'from which is applied by way of a lead C to the non-inverting input of an amplifier 79, the output of which applies a negative, inhibiting signal by way of a diode 94A to terminal W when the OR line is held positive for any reason.

A signal developed by PD,7 and denotive of the raising of a pivoted flap by the passage of the note, is received at terminal 1317 and is applied by way of amplifiers 75 and 80 and by way of a diode 100 to OR line 97 so to inhibit acceptance if the flap is raised.

OR line 97 also receives by way of ter minal 60 of the common outputs of twin amplifiers 501 to 5 8 and is thus held positive to inhibit acceptance unless the outputs of the whole of the photo-diodes connected to those units are within the respective preset limits.

Logic circuits (Figure 5) When the presènce of a note is sensed by PDs a signal is developed at terminal 135 and is applied by way of an amplifier 111 and an inverting gate 112 to NAND gate 113. This gate also receives signals from terminal W by way of an inverter 115 and from a latch 116 when this latter is in the reset condition. Gate 113 thus yields an output signal to set a latch 114.

When the inhibiting signal at terminal W is remoyed, denoting that a proffered note is within acceptable limits, a mono stable trigger 117 provides a signal to a gate 118 that also receives signal from latch 114 in its set condition and from a further latch 119 in its reset condition.

Gate 118' t"us applies a signal to set latch li6; and this delivers a signal to a gate 120, to which is also applied a signal from set latch 114. Gate 120 yields a signal to a gate 12i that is also receiving a signal deriyed fro in the FLAP photo-diode PUD17, that is applied to gate 121 via terminal 82 and another signal, received over a lead he that is derived as described below.

The "flap closed" signal received at terminal 82 is applied by way of an inverting gatel22 to a gate 123, that also receives signal from PDs via amplifier 111 and from latch 116, when this latch is set. The Out- put of ga'te 123 sets latch 119. When set, latch;119 applies a signal to a gate 124 that also receives a signal from terminal 82 and a signal from set latch 116.Gate 124 thus provides a signal via a lead' J and an ioverting gate 125 to initiate a monostable trigger 126 that, in its set condition, yields a signal to gate 121 over le"ad H. Gate 121 then yields a signal over a lead'G ànd by way of an inverting gate 127 to a terminal 128 to energise the motor relay (Figure 6). The motor is thus ener gised and the note will be drawn iiito thet apparatus. In moving the note raises the flap and thus masks PD17.

As it moves forward the trailing edge of the note clears PDs and the resultant signal at the output of amplifier 111 is fed through gate 123 to set latch 119.

When the trailing edge of the note passes PD17 and this is again illuminated, a signal is applied over l'ad J to initiate a monostable trigger 129; 'the Q output of which.

yields a credit pulse which, when a link 130'is set to" "the "1" position, as shown in full line, is passed by way of an inverting gate 131 to a terminal 132 to actuae an acceptance relay (Figure 6).

When the apparatus is set to accept 5 nptes by link 130 being in its "5" posi tion, a pulse from the Q output of mono stable trigger 129 sets a latch 133 which in turn initiates a monostable trigger 134 to which feedback is applied by way of a diode 135 to cause it to act as a pulse-train generator. The pulses generated by monostable trigger 134 are applied to link 130 and thence to output terminal 132. These pulses are also applied to a counter 136 which, when five pulses have been counted, applies a signal by way of an inverting gate 137 to reset latch 133, thus ending pulse generation. As this occurs a signal is applied from latch 133 to reset counter 136.

During the time latch 133 is set, a signal is applied from the latch by way of an inverting gate 138 and a diode 139 to provide from; terminal 128 an inhibit signal to this acceptor and to other note acceptors.

The Q output of monostable trigger 129 is also applied by way of a lead F to a gate 140, the output of which is applied by way of an inverting gate 141 to a lead K to reset latches 116, 119, 120 as well as counters 148, 149 and latches 152, 153 not yet described.

Additional cross-coupling is provided by gates 142, 143, 144 and 145 as will be described below, to check that the states of the latches 114, 116,119 and the input signals change to the, correct states at the end of the cycle. If the flap should be lifted by a jammed note a motor drive is ensured to clear the note,.

The following parts of the circuit detect and prevent certain attempted fraudulent operations.

a) Pull 'back of note after acceptance.

(i) If this is attemped before latch 119 is set the mis-òperation is detected by gatel4;1 which, if PD5 is- un covered when PD6 is covered (re,- verse movement df note) resets all of latches 114, 116, 119 via gates 140, 141.

(ii) If note withdrawal is attempted after latch 119 is set, gate 145 detects that PD6 ise recovered after the latch has been set and all three latches are again reset.

b) Feed of half-note.

Gate 142 detects that PD17 is not covered by the lifted flap, which would be the case wih a normal note, at the time that PDG is cleared and PDs is still covered.

Latch 116 is thus reset, which results in the note being taken in but credit not being given.

c) Substitution of blank paper for note after acceptance.

PD11 is responsive to note thickness and yields at 1316 a signal that is amplified by amplifiers 71 and 83 and is passed by way of terminal 84 directly to reset lead K to reset the latches.

An additional check on correct operation is provided by a monostable trigger 147 fed from pulses derived from one or more of the outputs from the photo-diode amplifiers 127 . . 1217 and driving seriesconnected counters 148, 149 of which selected stages are connected to gates 150, 151. When a predetermined count is attained, a signal is applied from gate 150 to set a latch 152 and thuse remove an inhibit signal that is otherwise applied via diode 154 to monostable trigger 129. When a higher predetermined number is attained, a signal is fed from gate 151 to set latch 153, which then applies an inhibit signal by way of a diode 155 to monostable trigger 129. If monostable trigger 129 is thus inhibted a signal appears at its Q output that causes reseting of the latches.

In the power supply and relay circuits shown in Figure 6, an alternating-current simply received at terminals 170. is anplied to a portion of the primary winding 171a of a transformer 171. The voltage appearing across the whole of primary winding 171 is applied by way of contacts 221a of a relay 201 to the motor 306 driving the rollers by which the note is drawn into the apparatus. Relay 201 is energised when, as has already been described, a negative potential is applied to a terminal 128, connected to one end of the relay winding the other end of which is connected to the positive supply line.

A secondary winding 171b of transformer 171 is rectified by a bridge rectifier 173 and applied across an output capacitor 180 to a stabiliser circuit in which a frac tion of the direct potential appearing across caDacitor 180, selected by a potentiometer 175 is compared in an amplifier 176 with the voltage across a Zener diode 177, the difference or error signal being applied to control a transistor 178 connected in series in the path of the direct current supplied to the apparatus.

This part of the apparatus includes also a relay 202 that is energised when earth potential appears at a terminal 132 as already described. Relay contacts 202a of relay 202 are included by way of terminals 203 in a circuit of vending apparatus to which the present invention is attached, in order to establish an appropriate credit.

This corresponds to the provision of an enabling signal on lead 309 of Figure 7.

A tone-generating device 204 is energised in parallel with relay 202 to give an audible signal of note acceptance to the purchaser.

WHAT WE CLAIM IS:- 1. Currency note identification apparatus including means arranged to guide a currency note along a predetermined path, means for illuminating respective portions of a currency note when said note is disposed at a predetermined position in said path, a plurality of photosensitive means arranged to yield individual signals denotive of optical characteristics of said respective portions of said note, individual comparators each arranged to compare a respective one of a first plurality of said individual signals with two respective reference levels and to develop an enabling signal only when the respective said individual signal has a value between the respective said reference levels, means arranged to develop an inhibiting signal except when all of said comparators yield respective said enabling signals, and logic means arranged to provide a credit denotive signal only when said inhibiting signal is absent at a time when a further plurality of said individual signals attain respective values denoting that said note is in said predetermined position.

2. Apparatus in accordance with claim 1 wherein each said comparator means comprises two difference amplifiers, means arranged to supply the respective said individual signal to an inverting input of a first said difference amplifier and to the non-inverting input of the second said difference amplifier, adjustable potentiometer means arranged to show the voltages at the non-inverting input of said first difference amplifier and at the inverting input of said second difference amplifier to be individually adjusted, an output terminal and a diode coupling the ouput terminal to said output terminal for signals of the same polarity.

3. Apparatus in accordance with claim 1 or claim 2 and further including means responsive to said enabling signal for advancing said note from said position into a receptacle by way of a means preventing

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   of latches 114, 116, 119 via gates 140, 141.

   (ii) If note withdrawal is attempted after latch 119 is set, gate 145 detects that PD6 ise recovered after the latch has been set and all three latches are again reset.

   b) Feed of half-note.

   Gate 142 detects that PD17 is not covered by the lifted flap, which would be the case wih a normal note, at the time that PDG is cleared and PDs is still covered.

   Latch 116 is thus reset, which results in the note being taken in but credit not being given.

   c) Substitution of blank paper for note after acceptance.

   PD11 is responsive to note thickness and yields at 1316 a signal that is amplified by amplifiers 71 and 83 and is passed by way of terminal 84 directly to reset lead K to reset the latches.

   An additional check on correct operation is provided by a monostable trigger 147 fed from pulses derived from one or more of the outputs from the photo-diode amplifiers 127 . . 1217 and driving seriesconnected counters 148, 149 of which selected stages are connected to gates 150, 151. When a predetermined count is attained, a signal is applied from gate 150 to set a latch 152 and thuse remove an inhibit signal that is otherwise applied via diode 154 to monostable trigger 129. When a higher predetermined number is attained, a signal is fed from gate 151 to set latch 153, which then applies an inhibit signal by way of a diode 155 to monostable trigger 129. If monostable trigger 129 is thus inhibted a signal appears at its Q output that causes reseting of the latches.

   In the power supply and relay circuits shown in Figure 6, an alternating-current simply received at terminals 170. is anplied to a portion of the primary winding 171a of a transformer 171. The voltage appearing across the whole of primary winding 171 is applied by way of contacts 221a of a relay 201 to the motor 306 driving the rollers by which the note is drawn into the apparatus. Relay 201 is energised when, as has already been described, a negative potential is applied to a terminal 128, connected to one end of the relay winding the other end of which is connected to the positive supply line.

   A secondary winding 171b of transformer 171 is rectified by a bridge rectifier 173 and applied across an output capacitor 180 to a stabiliser circuit in which a frac tion of the direct potential appearing across caDacitor 180, selected by a potentiometer 175 is compared in an amplifier 176 with the voltage across a Zener diode 177, the difference or error signal being applied to control a transistor 178 connected in series in the path of the direct current supplied to the apparatus.

   This part of the apparatus includes also a relay 202 that is energised when earth potential appears at a terminal 132 as already described. Relay contacts 202a of relay 202 are included by way of terminals 203 in a circuit of vending apparatus to which the present invention is attached, in order to establish an appropriate credit.

   This corresponds to the provision of an enabling signal on lead 309 of Figure 7.

   A tone-generating device 204 is energised in parallel with relay 202 to give an audible signal of note acceptance to the purchaser.

   WHAT WE CLAIM IS:- 1. Currency note identification apparatus including means arranged to guide a currency note along a predetermined path, means for illuminating respective portions of a currency note when said note is disposed at a predetermined position in said path, a plurality of photosensitive means arranged to yield individual signals denotive of optical characteristics of said respective portions of said note, individual comparators each arranged to compare a respective one of a first plurality of said individual signals with two respective reference levels and to develop an enabling signal only when the respective said individual signal has a value between the respective said reference levels, means arranged to develop an inhibiting signal except when all of said comparators yield respective said enabling signals, and logic means arranged to provide a credit denotive signal only when said inhibiting signal is absent at a time when a further plurality of said individual signals attain respective values denoting that said note is in said predetermined position.
2. 2. Apparatus in accordance with claim 1 wherein each said comparator means comprises two difference amplifiers, means arranged to supply the respective said individual signal to an inverting input of a first said difference amplifier and to the non-inverting input of the second said difference amplifier, adjustable potentiometer means arranged to show the voltages at the non-inverting input of said first difference amplifier and at the inverting input of said second difference amplifier to be individually adjusted, an output terminal and a diode coupling the ouput terminal to said output terminal for signals of the same polarity.
3. 3. Apparatus in accordance with claim 1 or claim 2 and further including means responsive to said enabling signal for advancing said note from said position into a receptacle by way of a means preventing

   withdrawal of said note and wherein said logic means also includes means responsive to the passage of said note beyond said withdrawal-preventing means to permit the provision of said credit denotive signal.
4. 4. Apparatus in accordance with claim 1, 2 or 3 wherein two of said light-sensitive means are arranged to receive light respectively transmitted through and reflected from the same portion of said note, and means whereby the signals derived from said two light-sensitive means being compared and compared with reference levels to yield a said enabling signal when the amounts of light received thereby are predeterminedly related.
5. 5. Apparatus in accordance with any of claims 1 to 4 wherein signals from a said light-sensitive means which in use develops a pulsatory signal in response to movement of said note along said guiding means are applied to counter means arranged to yield a said enabling signal only when the number of pulses developed by said light-sensitive means lies between predetermined limits.
6. 6. Currency note identification apparatus substantially as herein described with reference to the accompanying drawings.