GB2027914A - Quantity verifying weighing apparatus - Google Patents

Abstract

Quantity verifying apparatus comprises a weigher (12) for weighing a batch of bank notes or coins and a keyboard (13) for entry of the expected value of the batch. From these inputs, a micoprocessor (10) determines the class or denomination of the notes or coins and, from a series of weight-value factors stored for the different classes, calculates a monetary value corresponding to the weight of the batch for comparison with the keyed-in value. A display is provided to provide a visual output indicating whether or not any deviation between the keyed-in value and calculated values is within acceptable limits. The weigher includes a dual-ramp A-D converter 16-20 whose conversion cycle is controlled by the microprocessor without requiring any counting capacity additional to that incorporated in the microprocessor chip. <IMAGE>

Description

SPECIFICATION Quantity verifying weighing apparatus This invention relates to weighing apparatus for use in the weighing of banknotes and coins to check the count or money value of batches thereof, for example in banks or other establishments where speedy and reliable checking of large quantities of cash is called for. Such apparatus is hereinafter referred to as "quantity verifying weighing apparatus".

It is usual for banknotes to be sorted and bundled into batches of the same denomination, for example Bank of England 1, 5 and 10 notes each form a class in which the individual notes are substantially uniform in weight but differ from the weight of notes in the other two classes because of the difference in size, and the quantity in the batch (which can be expressed as a number of notes e.g. 100 times 1 notes or as the money value of the batch e.g. 'i 00) can be checked by weighing and distinguished by weight from batches made up of notes of the other denominations but to the same number or money value (e.g. 100 times 5 notes or 100 in 5 notes).

In the case of coins, these are usually classified in such a way that a mixture of certain coins of non-uniform weights bears a direct proportion to their money or other value even though the number of coins of that class making up that value may vary. British coinage has long been designed so that its weight is a function of its face value, thus any mixture of lOp, 5p and 2+p cupro-nickel coins (mixed silver) to a given face value (e.g.

5) will weight the same; likewise in the case of "mixed bronze" (2p, ip and ip) coins.

Simple weighing scales or balances are in common use for quantity verifying coins, there being little likelihood of error because a coin is durable and slow to wear in circulation, and the weight of an individual coin is easily detectable. It has also been proposed to verify quantity of bank notes by weighing as manual counting is tedious, liable to error, and occupies a great deal of bank teller's time, delaying customers, while mechanical counting means are often complex and not always reliable as performance may be adversely affected by the condition of the notes.

However, there are also problems arising in check weighing banknotes due to manufacturing tolerances, the effects of humidity on the paper and especially the results of wear and handling, e.g. impregnation with dirt and grease, or tearing and/or repair with adhesive tape. An individual note is not substantial in weight but its money value may be high hence weighing must be effected to close tolerances.

Moreover, any quantity verifying apparatus must, to be commercially viabie, be simple to operate so that the actual time in setting up the machine is kept to a minimum and operation of the machine can be learnt without special training.

According to the present invention, we provide quantity verifying apparatus comprising scale means for producing an electrical signal representing the weight of a batch of like currency notes or coins when applied to the scale means, a keyboard dor entry of a first, declared value of the batch of notes or coins applied to the scale means, means for storing for each class of currency a respective factor relating weight and value for that class, means responsive to the weight and value data provided by the scale means and the keyboard for ascertaining whether the weightvalue relationship lies within a predetermined range about any one of said stored factors and means for computing from the weight data and related stored factor, if any, a second value for said batch of articles for comparison with the first value.

As used herein, in the case of UK currency, the different classes of currency are as follows: 10, 5 and 1 notes (possibly also 20), 50p coins, 1 Op, 5p and 2+p coins (all considered as a single class) and 2p, 1 p and Tp coins (again all considered as a single class). Thus it will be seen that all that is required of the operator is to place the batch of notes or coins on the scale and key-in the declared value thereof.

As mentioned above, verifying quantities of banknotes by weighing is subject to the problems of manufacturing tolerances and factors such as humidity, wear and tear etc. which may affect the weight of the individual notes.

Thus, for batches of used notes, the computed values for those batches may differ somewhat from the declared values even though the latter are correct. In accordance with a preferred feature of the invention therefore, preferably the apparatus includes useroperable means for selectively varying any one or more of said stored factors to enable the condition of the notes or coins to be taken into account. In one embodiment of the invention, user-operable means is provided to enable the operator to indicate which class is to be calibrated and means is provided for computing a fresh weight-value factor. Alternatively a scaling factor may be derived according to the difference or ratio between the weight of a known value of non-standard notes/coins of that class, as sensed by the scale means, and the weight of an equal value of standard notes or coins.Such scaling factors may then be used by the apparatus, in conjunction with the aforesaid stored factors, to compute said second value and also to determine whether the weight-value relationship lies within a predetermined range about the modified stored factors.

Preferably, the apparatus includes means for determining any deviation of the tentative value from the computed value and providing a visual display which indicates the presence or absence of any such deviation. The display conveniently provides an indication of the extent of the deviation and preferably includes a tolerance zone to differentiate between acceptable and unacceptable deviations.

The apparatus preferably also includes a facility whereby the value of a batch of currency can be ascertained and for this purpose the apparatus includes means for placing it in either a check mode or a counter mode wherebin the number or value of notes forming a bundle is computed, the computation being carried out by dividing the weight of the batch or bundle by the appropriate weight-factor.

The invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a block diagrammatic view of an electronic quantity verifying bank scale in accordance with the invention; Figures 2a-2c, 3, 4a-c, 5, 6 and 8 are flow diagrams of the main programme and sub-routines performed by the microprocessor of the scale; Figure 7 is a diagrammatic view of the display and keyboard layout of the scale; and Figures 7a to 7j are views showing different conditions of the display section of the scale.

The following description is given on the basis that in checking a given class of currency, a deviation of plus or minus one unit of that class between the keyed in value and computed value derived by weighing, is acceptable. Thus, for example if in checking the weight of a batch of mixed "copper" coins whose tentative value is keyed in as 4, the value computed from the weight of the batch is found to be 3.99p (one ip being assumed to be the basic unit for that class of coin) then the deviation is acceptable and can be indicated as such but if the deviation is found to exceed one +p then the deviation is not acceptable and is to be indicated as such.

Similarly, for the class of coins formed by lOp, 5p and 2ip coins, any deviation within plus or minus 2+p can be indicated as acceptable but larger deviations are to be indicated as unacceptable. However, it is to be understood that this is purely by way of example and that the tolerance range may be altered to suit requirements.

As will become apparent from the following description, the scale is operable in three modes which will be referred to as the CHECK mode, the CAL mode and the COUNT mode.

Referring now to Fig. 1, a scale comprises a microprocessor unit 10 driven by a clock 11 and having associated input and output data devices associated with it in the form of weight signal producing section 12, an electronic keyboard 1 3 and an electronic digital display 1 7. The section 1 2 includes a load responsive transducer in, for example, the form of a strain gauge bridge 14 which, in known manner, supplies an analogue output representing the load applied to the scale to an amplifier 1 5. The bridge 14 is energised by a reference voltage source V + . The output of the amplifier 1 5 and the reference voltage source are selectively connectible to the integrator 1 6 of a dual-ranap A to D converter via a solid state switch 1 8 which has three switch states in which the output of amplifier 15, the reference voltage source V +, and the output of the integrator 1 6 are respectively connected to the input of the integrator 1 6. The switch 1 8 is controlled by the microprocessor 10 as explained below.

The output of the integrator 1 6 is connected to a comparator 20 for detecting zero crossover of the output of the integrator.

The operation of the dual-ramp A to D converter is well known in the art but will be explained briefly herein as the control of the A to D conversion by the microprocessor involves certain novel features. The A to D conversion is carried out repeatedly with a cyclic period determined by the microproces- sor, for example once every 80 milliseconds; the exact duration of the cycle is not however important in the present context. During each cycle, the switch 1 8 is operated to connect the converter to the signal source, i.e. the output of the amplifier 15, for a fixed period of time (as explained hereinafter) which may be one half cycle (40 mi8liseconds). During this period, the signal is integrated and the output of the integrator ramps upwardly from zero.At the end of the fixed period, the switch 1 8 is operated to connect the reference source V + to the integrator and because the poiarity of the reference source will be opposite to that of the signal source (because of the bridge configuration), the output of the integrator is caused to ramp back towards zero. The zero crossing is detected by the comparator 20 and the ''zero detect" signal is used by the microprocessor as a cue to store the count reached by a counter which is set counting at the instant that the reference source is connected to the integrator. Thus, the count reached by that stage constitutes a digital representation of the analogue signal sampled during that conversion cycle. In addition, in response to the zero detect signal, the microprocessor also changes the switches 18 to connect the input from the integrator to its output and thereby reset the same to zero in preparation fo the next A to D conversion cycle.

The microprocessor 10 is programmed in accordance with the flow diagrams shown in Figs. 2 to 6 and 8 to which reference will now be made. The flow diagrams consist of a series of diamond-shaped and rectangular blocks. Each diamond block corresponds to a question having a yes or no answer which may be obtained by conventional computer techniques. Each rectangular block corresponds to the performance of a specific function such as adjusting a weight valve gener ated by the weight signal producing section 1 2 for a tare weight value.

Figs. 2show the flow diagram of the main programme sequence performed by the CPU of the microprocessor. At switch-on, the machine enters an "initialisation period" (block 40) during which the microprocessor causes the display 12 to read out the legend "dont use" (see Fig. 7a). It will be understood that this legend can be readily obtained by appropriate energisation of selected segments of conventional figure of eight seven segment display indicators forming part of the display. The purpose of the initialisation peri6d is to allow the strain gauge bridge to come to a steady state condition. Also in this period, a RAM (random access memory) of the microprocessor is cleared and various constants from look-up tables (ROMS) are loaded into the RAM.

The microprocessor includes a zero factor store which stores a factor to take account of any deviation of the strain gauge bridge output from "true" zero and during the initialisation period, the zero factor store is first loaded with a predetermined limiting value and is then incremented towards a value corresponding to the actual "true" zero then indicated by the output of the strain gauge bridge.

When the zero factor corresponding to the "true" zero sensed by the strain gauge is arrived at, the zero factor is stored in memory and the digital display is then caused to display "nought" (see Fig. 7b).

At this point, the scale is ready to use and the main programme is waiting in the loop 41 for a "new reading ready" flag to set up. This flag is set up during each machine (i.e. A to D conversion) cycle following sensing of zero detect by the comparator 20. Thus, in response to zero detect, the flag is set by storage of a bit in a particular memory location in the microprocessor. The block 42 therefore checks the condition of this memory location; if the flag is not set then the programme returns to loop 41 but if it is set, the microprocessor proceeds to subtract the stored zero factor from the new weight reading and the programme then proceeds to block 43 in which the result of the subtraction is checked to determine whether (a) it is less than zero, (b) less than a predetermined threshold value greater than zero or (c) greater than the threshold value.If the result is less than zero then the zero factor store is adjusted towards the new "true" zero value and the display is blanked (block 44) to indicate that the scale is under-range. The programme then jumps back to loop 41 and waits for "new reading flag" to be set again before proceeding onto block 43.

If the result is greater than or equal to zero but less than threshold, this is taken to represent a no-load condition and the reading obtained from the A to D conversion is assumed to be the current "true" zero. In these circumstances, the display is loaded with "zero" (block 45)-see Fig. 7 b and if the current reading is different from the stored zero factor, the zero factor store is adjusted (block 46) by a small amount towards the current "true" zero value. Thereafter the programme returns to loop 41.

If the result is greater than threshold, then it is assumed that there is a weight present on the scale and the programme proceeds to block 47 which checks the condition of a switch (not shown). This switch can be located internally of the machine housing and is provided to facilitate initial setting up of the scale by a service engineer. Normally, the switch is not actuated and consequently the programme will normally proceed to block 48.

However, when the internal switch is actuated, the microprocessor causes the display 1 7 to display the reading provided by the weight signal producing section 1 2 (block 49). This enables the service engineer to observe the display output of weight while adjusting the machine.

Assuming that the internal switch is not operated, the microprocessor checks (block 48) to see which mode the machine is required to operate in, i.e. CHECK mode, CAL mode or COUNT mode, according to the instructions which have been received via the keyboard 1 3. When such a calibrate (CAL) or COUNT instruction is present, the programme branches to the subroutine of Fig. 6 or Fig. 8 as will be exaplained below. For the present, it will be explained below.For the present, it will be assumed that the machine is operating in the check mode in which case the programme proceeds to block 50 at which point the current reading (corrected by the zero Factor) is divided by the value keyed in via the keyboard 1 3. As explained above, this value yvill represent the declared or tentative value of the money placed on the scale. For instance, if the declared value is 200 (whether in 20, 10, 5 or 1 notes), the number 200 will have been keyed in and will be displayed (see Fig. 7c). This quotient is now compared with data stored in the microprocessor memory representing ranges of weight to value ratios for different classes of currency.

rhus, at block 52, the quotient Q is compared Nith the range band (range 1) stored for, for example, copper coinage to check whether Q is within or outside range 1. If outside, then the programme proceeds to block 53 where Q is compared with range 2 data for, for example, silver coinage (10p, 5p, 2it). Again if Q is outside the range band, the programme proceeds to block 54 and so on, if necessary, through blocks 55 onwards to block 57 until O ia found to fall within one of the range bands. If the programme reaches the final range band block and Q falls outside the range band associated with the block (e.g.

10 notes or 20 notes if the machine is intended for use with 20 notes), the programme then branches off to the "fail" subroutine of Fig. 3 in which the microprocessor causes the display to indicate the legend "FAIL" and to clear any difference indication that may be present on the display. The programme then returns to loop 41.

If Q is found to fall within any one of the range bands, then a further check (block 120) is made to see if the keyed-in value is valid for that range, i.e. 21 on the 5 range is not valid. Where the validity test is satisfied the programme proceeds to the next block 58-63 which causes the display to read-out symbols indicating the selected range band. These symbols are displayed in the display section 34 and the different displays are shown in Figs. 7diwhich respectively symbolise the 10, 5, 1, 50p silver and copper currency classes (and also 20 if the machine is to be used for checking 20 notes).For example, if a bag of mixed up 2p, I p, +p copper coins of declared value 4.5Op is placed on the scale, the digital display will be as shown in Fig. 7j.

It will be noted that because the coins are bagged, the display indicator 35 will illuminate a BAG/BAND legend in response to actuation of tare button 32 of the keyboard to indicate that the tare facility is required (i.e.

for the bag or for a band in the case of notes).

The range bands are made j Y% around the true values, where Y may, for example, be 10, the true values being the quotient of weight and value for a standard batch of the currency class concerned.

After the function specified by block 58 to 63 has been performed, the programme proceeds to block 64 to 69 wherein the true range factor and tare data for the particular class in question is retrieved from storage and placed in a suitable memory location for subsequent use. The programme then proceeds to block 70 where a check is made for a tare instruction entry via the keyboard 1 3. If a tare entry has been made, the programme branches to block 71 which causes retrieval of a tare value from storage and subtraction thereof from the weight. In practice, the tare information may be limited to two values corresponding to the weights of a standardised wrapper for banding together batches of notes or a standardised plastics bag for coinage.Thus, if for example the programme has arrived at block 70 via blocks 52 and 54 (copper, silver and 50p range bands), the stored tare value retrieved for those classes will correspond to the weight of a standard plastic bag whereas if the programme has progressed via blocks 55 to 57, the stored tare value retrieved will correspond to the weight of a wrapper. It is to be understood however that a wider range of tares may be provided if desired, for example a different value of tare may be stored in memory for each class of currency.

From block 70, the programme proceeds, either directly or via block 71 depending on whether tare is required or not, to block 72 where the net weight of the batch of notes or coins is divided by the appropriate range factor to compute the value of the batch, which value may be the same as the keyed in declared value or different depending upon the condition of the notes or coins.The computed value is the compared with the keyed-in value (block 73) and any difference is evaluated in terms of a units difference, e.g. in the case of 10, 5 and 1 notes in terms of 10, 5 and 1 units respectively (or if desired in terms of 1 units for all three denominations), in the case of 50p coins in terms of 50p units, in the case of "silver" coins in terms of 2p units and in the case of "copper" coins in terms of ip units. Alternatively, if desired, the difference in the cases of silver and copper coins may be evaluated in terms of 5p and 1 p units.Depending on whether the difference is less than or greater than two units or within plus or minus two units, the programme proceeds to block 74, 75 or 76 and the microprocessor operates the display accordingly as described hereinafter.

Thereafter the programme returns to loop 41 and the above described procedure is repeatedly performed, subject to interruption by certain subroutines which will be described below.

Fig. 7b shows the layout of the electronic display and keyboard of the machine. The keyboard 1 3 comprises the usual digit keys 0-9, a clear key 31 to clear for example an erroneous entry and, as previously described, a tare (or BAG/BAND) key 32, i.e. twelve keys in all. The keyboard circuitry is conveniently so arranged that once a given value is keyed in, that value will remain and will be applied to subsequent weighings until superseded by another keyed-in value. This allows a number of bundles of similar quantities to be checked without having to repeat the key in the same value.

To simplify entry of the declared value, the arrangement may be such that the operator need not differentiate between notes and coinage when entering the declared value. Instead the microprocessor determines whether the declared value is in terms of coins or notes and, if necessary, locates the decimal point in the correct position in the display. For example, if the operator wishes to declare a value of 2.25 in coins, he simply enters 225 and after the microprocessor has determined that the declared value is in coinage during the course of executing the routine of Figs. 2a and 2b, the programme may include a step, e.g. immediately preceding block 70, in which the decimal point is inserted at the appropriate place, i.e. 2.225. If, on the other hand, the declared value is 225 in say 1 notes, no decimal point adjustment will be made.

The electronic display 1 7 comprises a number of figure of eight seven segment display indicators organised into a group 33 of four indicators for displaying declared value entered via the keyboard when operating in the CHECK mode or the amount calculated from the weight when operating in the COUNT mode (or weight when the internal switch is operated) and a group 34 of three indicators for displaying the note or coinage symbols (see Fig. 7dto 78. The display 17 also includes a legend indicator 35 which can be energised to display the legends "COUNT", "CHECK" and "BAG/BAND".The electronic display further comprises a bargraph consisting of four display indicators 36 to 39 each comprising eight parallel electrodes and arranged so as to divide the overall bargraph display into 32 divisions, each of which corresponds to 1 /8th of a note or coinage unit.

The middle two indicators are enclosed within a rectangle marked "ACCEPT" whilst above the other two indicators the word "REJECT" is marked.

The bargraph is energised in accordance with the result of the comparison made during the performance of instruction of block 73. If the comparison shows that the computed value is equal to the declared value then the electrodes of indicators 37, 38 disposed centrally within the ACCEPT rectangle are energised. If the deviation is less than i 1 unit then one of the electrodes of indicator 37, 38 is energised, if the deviation is + 1 i.e. the declared value exceeds the computed value by one unit) the extreme right hand electrode of indicator 38 is energised and if it is - 1 the extreme left hand electrode of indicator 37 is energised. For other values within the range + 1, one of the intermediate electrodes will be energised, preferably continuously (as viewed by the operator).If however the difference exceeds i 1 but is not greater than + 2 then one of the electrodes of indicators 36 or 39 is energised, preferably in a flashing mode so as to enable the operator to distinguish readily between deviations lying within and without the + 1 range. For example if the deviation is - 2 units the extreme lefthand electrode of indicator 36 is flashed on and off.

If the difference exceeds + 2 units but is less than + Y% (the limits of the respective range band), the microprocessor is programmed to energise all of the electrodes of the bargraph. As explained previously, if the difference is greater than + Y%, this will be detected as the programme proceeds through the blocks 52 to 57 leading to the "FAIL" subroutine of Fig. 3.

As described above, the division defined by the electrodes of indicators 37 to 39 correspond to 1 /8th of a unit. However they may be arranged so as to define for example i of a unit, e.g. by arranging for eight divisions to correspond to to units instead of one. It is also to be understood that other forms of display are possible e.g. the bargraph display could be replaced by two or more figure of eight seven segment display indicators, one to indicate the sign of the deviation and the other or others to indicate its mgnitude.

The mode of operation is selected by operation of the CAL and MODE switches 200 and 202. As mentioned previously, the machine is operable in the COUNT, CHECK and CAL mqdes. At switch-on the machine may be programmed to enter the CHECK mode and display 35 is illuminated to display the legend CHECK.

When it is desired to use the COUNT facility, the MODE switch 202 is operated causing illumination of the legend COUNT in display 35 and the machine then operates in the COUNT mode as will be explained hereinafter.

The machine then remains in the COUNT mode until switch 202 is operated again whereupon the machine reverts to the CHECK mode. Alternatively if the CAL switch 200 is operated, the machine proceeds to operate in the CAL mode until switch 202 is operated to return the machine to the CHECK mode. At any instant, the display 35 indicates which mode has been selected.

The keys of the keyboard 1 3 are dual functional according to the mode of operation.

In the CHECK mode, the symbols on the faces of the keys represent the information inputted to the microprocessor. In the COUNT mode only the keys labeled 1, 4, 7, C, 3, 6 and 9 are operational and the information inputted corresponds to the legends 2c, 1 Oc, 50c, 1 n, 5n, 1 On, 20n alongside those keys. These legends identify the denomination of the currency, e.g. 2c represents 2p coins and 1 On respresents 10 notes. Thus, when operating in the COUNT mode if a batch of say 10 notes is to be evaluated, the operator will place the batch on the scale and depress key 3.

In the CAL mode, only keys C, 3, 6 an 9 are operational because calibration of the coinage weight-value factors will not usually be necessary. Thus, operation of for example key C indicates that the 20 note range is to be calibrated.

Referring now to Figs. 4 > c, these show flow diagram of the REGULAR INTERRUPT subroutine of the programme which governs the A to D conversion cycle and multi-plexing of the display 1 7. The LSI chip forming the microprocessor may be an Intel 8048 chip which incorporates an 8 bit hardware counter and to utilise this relatively low capacity counter for control of the A to D conversion cycle without having to resort to using a counter separate frm the LSl chip, it is used in conjunction with the microprocessor memory so that, in effect, the A to D conversion is controlled by a counter which is part hardware and part software.Thus, the hardware counter which is clocked by the high frequency clock 11 repeatedly counts from 0 to 255 and each time it reaches the 255 count the contents of a preselected memory location of the microprocessor is incremented by one from 0 until it reaches a predetermined cunt X which, in this embodiment, will correspond to the number of times the hardware counter reaches full capacity counter over a period of 40 milliseconds. The REGULAR INTERRUPT routine is initiated every time the hardware counter reaches 255 (every 510 microseconds in the present embodiment). At this point, the CPU is signalled to complete the instruction of the main programme currently being executed and then to branch to the Fig. 4 routine. The inernal software counter is at this stage checked (block 80) to see whether it has reached the count X.If the count is less than or equal to X, the software counter is incremented by one (block 81) but if it is greater than X, the microprocessor checks the ramp conditions (blocks 82 and 83). If, at this point, the ramp is in signal period (i.e. the first 40 millisecond period of the 80 millisecond cycle), the microprocessor changes over switch 1 8 (block 84) to connect the integrator 1 6 to the reference source V + and resets the software counter (block 85) to its start number, which may be 200.

If the ramp is not in the signal period, then it must either be ramping back to zero (reference period) or being reset (dead period), i.e.

in the second half of the 80 millisecond cycle.

In either case, the switch 1 8 is changed to the signal source position (block 85) and the software counter is reset to its start number (block 85). If however, when the check is made at block 83, the ramp is found to be above its zero point, then the display 1 7 is energised (block 87) to display "LOAD H1" on indicators 33, 34 to indicate that the weight applied to the scale is over-range.

After servicing that A-to D converter as described above, the CPU proceeds to service the display 1 7 and the keyboard 1 3. As explained above, the keyboard has 14 keys in all and the display has 1 2 indicators, however there is no limit on the number of keys or indicators that may be used. The display scanning is controlled by software and one indicator is trobed every time the Figure 4 routine is carried out. Thus, over a sequence of twelve REGULAR INTERRUPT cycles, each indicator is trobed in turn and is loaded from storage with the relevant data to be employed by the respective indicator (blocks 88 and 89).Although each display indicator is only strobed once every twelve REGULAR INTER RUPT cycles, the speed of operation is such that the indicators appear to be continuously displayed except, of course, when a flashing effect is required as explained previously. To avoid ghosting effects between the displays, m the segments data for each indicator is cleared for a short interval while the indicator strobe is being changed from one indicator to the next (block 88).

The keyboard scanning and display indicator strobes are effected simultaneously so that for every indicator strobe, a given key is strobed and if the output of the keyboard is true, a code is stored appropriate to the entered key. Thus, at block 90 the given key is read after making an anti-bounce check. A check is then made (block 91) to see whether the key being examined was operated in the previous cycle that it came under scrutiny. If no key is operated, the CPU returns via block 1 21 (see below) to the next instruction in the sequence it was executing prior to the REGU LAR INTERRUPT. If no new key is operated (i.e. same key still held depressed), the programme branches to block 111 and restarts the 3 second timing interval (as explained below).

It is is established that a key has just been operated, the programme proceeds to test (block 208) whether it is one of the keys 200 and 202. If it is, the appropriate flags are set up (blocks 210, 21 2) for whichever mode has been selected and the programme exits this routine and returns to the main programme proceeds to check (block 214) the current operating mode of the machine. It the current mode is COUNT, the microprocessor stores (block 214) the weight-value factor associated with the key that has just been depressed and the three second timing delay is initialised (block 216) before the programme returns to the main routine.

On the other hand, if the current operating mode is the CHECK mode, the programme proceeds to block 92 where a memory location constituting a software key counter is checked to see whether it stores a count greater than 3. This key counter is incremented by 1 whenever a key is operated with a predetermined interval of time, e.g. 3 seconds, following a previous key operation and its count represents the number of digits that have already been entered in the display section 33. If the count is 4 then all four indicators of display section 33 will be energised and if it is 1 then only one indicator will be energised and so on. Assuming that the key counter stores a count of 4, then the current key operation signifies entry of a fresh declared value and the microprocessor resets the key counter to zero (block 93) and then clears the data relating to the previous key operations and stores the value of the currently operated key (block 94) for entry as the most significant digit during multi-plexing of the display. If, however, the key counter does not contain a count of more than 3 when checked at block 92, a check is made (block 95) to determine whether the currently operated key has been operated within the predet ermined time interval, e.g. 3 seconds, from the last preceding key operation. If it has not, then the current key operation is taken to be the first digit of a fresh entry and the proce dure of block 94 is again followed.

Assuming the programme proceeds via block 94, the microprocessor then initiates the 3 second timing period (block 96). This tim ing period is set up as a predetermined count in a counter and is timed out by decrementing the counter each time the REGULAR INTER RUPT routine is executed via block 121.

Thus, if no new key is operated over a certain number of cycles of the REGULAR INTER RUPT routine, the counter will be decremented to zero which corresponds to timing out of the 3 second interval. This timing interval governs whether the next key operated constitutes entry of a less significant digit or entry of fresh data to replace the existing data, and finally increments the key counter (block 97) before returning to the main programme of Fig. 1.

If, on the other hand, the block 95 check indicates that the currently operated key is made within the 3 second timing interval the programme branches to block 98 where the data corresponding to the current keyis stored for display as a less significant digit in display section 3. The programme then proceeds to blocks 96 to 97 and back to the main programme of Fig. 1.

Referring now to Fig. 5, this Figure shows another subroutine which is carried out whenever the zero-detect signal is produced during the A to D conversion. In response to this signal, the combined software and hardware counter which controls the A to D conversion cycle is read (block 102) and stored (block 103) the "new reading" flag (see block 42, Fig. 1) and "zero period" flag (see block 83, Fig. 4) are set (block 104) and the digitiser ramp is changed over to zero period, via switch 18 (block 105). The microprocessor then reverts to the programme routine it was executing prior to the DIGITISER INTERRUPT.

Referring now to Fig. 6, this Figure shows the flow diagram for the calibration routine. If a calibration flag has been set up by operation of Key 200 when this is tested for at block 48, Fig. 2a, the CPU will branch to the Fig. 6 routine. The need for calibration may arise in circumstances where the condition of the notes may be affected by factors such as humidity or deterioration through use etc. In such case, if it is desired to check a number of batches of notes in such condition, the scale may be calibrated by applying a known number of notes and storing an adjusted weight-value factor for comparison with subsequent bundles of notes in like condition.

When a CAL flag is encountered at block 48, the CPU branches to the Fig. 6 routine and first of all, the microprocessor causes (block 220) the letters CAL to be displayed on the display section 34 for a preselected time interval, e.g. 3 seconds. During this time interval a check is made (block 232) to see whether any of the keys on the machine are operated. If a key operation does occur before this interval has lapsed, the programme exits the routine on the assumption that the CAL key 200 has been operated inadvertently and the machine reverts back to its normal working mode. If no key operation occurs in this time interval, the words CODE and CAL are displayed in display sections 33 and 34 respectively (block 224) for a further predetermined time interval, e.g. 5 seconds.During this period, the programme looks (block 106) for operation of one of the keys 9, 6, 3 or C which the operator operates to identify the range (1, 5, 10 or 20) which is to be calibrated. If not key is operated during this 5 second interval, the programme exits the routine and the word FAIL is displayed.

On the other hand, if one of the keys 3, 6, 9 or C is operated during this 5 second interval, the programme proceeds to calibrate that range. The calibration procedure requires the operator to place a predetermined value of notes on the scale to standardise the scale for that denomination, e.g. 500 in 5 notes or 100 in 1 notes. The microprocessor stores for each range full load data for a standard batch of notes, e.g. the weight for 100 standard 5 notes or 100 standard 1 notes, as the case may be.Once the CPU has determined which range requires calibration, the related full load data for that range is extracted from the appropriate store (block 107), the net weight (see block 43) is divided by the standard weight (block 108), the quotient is stored (block 109) in memory as a scaling factor to be used subsequently in conjunction with the range factor for 5 or 1 notes, as the case may be, and finally the display section 33 is set (block 110) to display 500 for 5 range and 100 for 1 range and the central electrodes of the bargraph are energised to indicate that calibration has been completed and the calibrated range factor is available for use in the checking of subsequent bundles. Thereafter the CPU returns to the loop 41 in the main programme.

Conveniently, to remind the user that any particular range has been calibrated (e.g. on the basis of a non-standard bundle of 1 notes) the scale may provide a visusl indication that the range in question has been calibrated. In one form this may consist of a horizontal bar above the respective symbol displayed at the left hand side of the display section 34.

Instead of recalibrating by means of scaling factors as described above, the full load data (blocks 107) may represent the number of notes (10, 5 or 1) standard notes corresponding to the full load capacity of the scale for the particular denomination. Thus, at block 108 the weight of the calibration batch of 100 notes is divided by the number of standard notes corresponding to the full load for the note denomination concerned to produce a range factor in terms of, for example, grams per 100 notes.

The scaling or recalibrated stored factors may be stored temporarily either until the machine is switched off or until the scale is used to check notes of a denomination other than for which calibration has been made.

Alternatively, they may be stored in a nonvolatile memory until updated by a subsequent calibration procedure. To avoid overlapping of the range bands, the calibration routine may be restricted only to use when the full load weight of the non-standard notes is within + 10% of the standard full load weight.

As described above, the operator is required to place a full load on the scale if calibration is desired, e.g. 100 1 notes of 100 5 notes. In a modification however the arrangement may be such that the calibration batch may be of any known value which is keyed in by the operator; in this event, the scaling factor will be determined by dividing the weight of the calibration batch by the standard weight of the known keyed-in value.

Referring now to Fig. 8, the programme enters this routine if a COUNT mode flag is encountered at block 48 (Fig. 2a). The microprocessor reads the keyboard (block 230) to determine the denomination of currency that the operator has placed on the weighing scale and has keyed in via the keyboard. It then checks whether the tare facility is required (block 232). If it is, the microprocessor retrieves the appropriate tare value from storage (bagweight for coins and bandweight for notes) and subtracts it from the total weight to produce the so-called nett weight value (block 234). The microprocessor then divides (block 236) the net weight value by the weight-value factor for the currency denomination concerned and displays (block 240) the value of the coins or notes on display 33. A check is also made to see whether the currency in question is coinage (block 238) and if it is the demcimal point on the display is adjusted (block 242). The bargraph display may be inhibited when the machine operates in the COUNT mode.

From the foregoing, it will be seen that the invention provides a machine for readily checking the declared value of a batch of notes and which includes the optional facility of indicating the number of notes or value of notes (or where desired the value of coinage) forming a given batch of unknown value.

Claims (12)

1. Ouantity verifying apparatus comprising scale means for producing an electrical signal representing the weight of a batch of like currency notes or coins when applied to the scale means, a keyboard for entry of a first, declared value of the batch of notes or coins applied to the scale means, means for storing for each class of currency a respective factor relating weight and value for that class, means responsive to the weight and value data provided by the scale means and the keyboard for ascertaining whether the weightvalue relationship lies within a predetermined range about any one of said stored factors and means for computing from the weight data and related stored factor, if any, a second value for said batch of articles for comparison with the first value.

2. Apparatus as claimed in Claim 1 including user-operable means for selectively varying any one or more of said stored factors to enable the condition of the notes or coins to be taken into account.

3. Apparatus as claimed in Claim 1 or 2 in which user-operable means is provided to enable the user to designate a class for calibration purposes and means for computing a fresh weight-value factor for the designated class.

4. Apparatus as claimed in Claim 1 or 2 in which means is provided for computing for a designated class a scaling factor corresponding to the difference or ratio between the weight of a known value of non-standard notes/coins of that class, as sensed by the scale means, and the weight of an equal value of standard notes or coins, such scaling factor(s) being used, in conjunction with the aforesaid stored factors, to compute said second value and also to determine whether the weight-value relationship lies within a predetermined range about the stored factors when modified by said scaling factors.

5. Apparatus as claimed in Claim 3 or 4 in which said scaling factors or recalibrated weight-value factors are stored temporarily, said apparatus reverting to the original stored weight-value factors each time it is switched off or until a different class is selected by the user.

6. Apparatus as claimed in any one of Claims 1-5 including means for determining any deviation of the declared value from the computed value and providing a visual display which indicates the presence or absence of any such deviation.

7. Apparatus as claimed in Claim 6 in which the display provides an indication of the extent of the deviation.

8. Apparatus as claimed in Claim 6 or 7 in which the display includes a tolerance zone to differentiate between acceptable and unacceptable deviations.

9. A microprocessor controlled analogue to digital signal converter of the kind which integrates an incoming analogue signal over a given interval of time and converts the time integral so formed into digitial form, characterised by the microprocessor chip including a hardware counter having a predetermined counting capacity, means for supplying a high frequency pulse train to said counter to continually cycle the same through its counting cycle, the microprocessor including memory storage constituting a software counter which is incremented each time the hardware counter reaches a preselected count, and said given interval of time being determined by the interval of time taken for the software counter to be incremented from a first value to a second value.

10. A microprocessor-controlled analogue to digital signal converter of the dual ramp type, wherein the incoming analogue signal to be converted is integrated over a given interval of time and in which an analogue reference signal of opposite polarity is thereafter applied to the converter until the integrator output is reduced to some predetermined value, for example zero, characterised by the microprocessor chip including a hardware counter having a predetermined counting capacity, means for supplying a high frequency pulse train to said counter to continually cycle the same through its counting cycle, the microprocessor including memory storage constituting a software counter which is incremented each time the hardware counter reaches a preselected count, and said given interval of time being determined by the interval of time taken for the software counter to be incremented from a first value to a second value, the software counter being reset to said first value upon expiry of said given time interval and allowed to continue incrementing until said integrator output attains said predetermined value at which time the contents of said hardware and software counters provide a digital representation of the incoming analogue signal.

11. Apparatus as claimed in any one of Claims 1-8 wherein said scale means includes a signal converter as claimed in Claim 9 or 10.

12. Apparatus as claimed in any one of Claims 1 to 8 or Claim 11 wherein the apparatus is selectively operable to divide the weight sensed by the scale means by a selected one of the weight-value factors to determine the value of a batch of notes or coinage placed on the scale means.

1 3. Ouantity verifying apparatus substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.