US 3682286 A
A method of electronically checking coins which comprises the steps of performing an indirect measuring operation upon the coins to be checked, obtaining electrical signals by virtue of the measuring operation characteristic of the coins undergoing checking. The thus obtained electrical signals are at least partially stored, the measuring operation is completed and the thus checked coins are evaluated to determine whether the coins have generated a signal characteristic of the specific type of coin desired to be checked.
Description (OCR text may contain errors)
United States Patent Prumm  METHOD FOR ELECTRONICALLY CHECKING COINS Georg Prumm, Kolner Strasse 235, D4283 Bergneustadt, Germany Filed: July 17, 1970 App]. No.: 55,752
 Foreign Application Priority Data July 19, 1969 Germany ..P 19 36 898.0 Sept. 5, I969 Germany ..P 19 0]8.l Nov. 4, 1969 Germany ..P [9 333.4 March 2, 1970 Germany ..P 20 09 622.4
US. Cl. ..l94/ A Int. Cl ..G07f 3/02 Field of Search 194/100 R, 100 A 51 Aug. 8, 1972  References Cited UNITED STATES PATENTS 3,373,856 3/ 1968 Kusters et a] 194/100 3,561,580 2/197] Meloni ..l94/1OOA Primary Examiner-Stanley H. Tollberg Attorney-Werner W. Kleeman 5 7 1 ABSTRACT 25 Claims, 18 Drawing Figures i f 101. Hi] 5 PATENTEDAIIG a m:
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BY M 11 ILUL/ ATTORNEY METHOD FOR ELECTRONICALLY CHECKING COINS BACKGROUND OF THE INVENTION The present invention relates to a new and improved method for the electronic checking of coins.
It is initially premised that two solutions are conceivable for the checking of coins: firstly, the static checking or measurement of stationary coins and, secondly, the dynamic checking or measurement of travelling coins. Static measuring techniques have not previously become known to the art. What has been known is simply the dynamic measuring technique in which the coins traverse a measuring apparatus and, thus, are checked with regard to their authenticity or to determine whether they belong to a certain coin classification.
When checking moving or sliding coins, there is measured the change of a so-called idling or no-load" amplitude influenced by the moving coins. The coin approaches a predetermined measuring point and again leaves such. As a result, there exists a continuously increasing or decreasing change of the amplitude level up to a certain maximum value and then a continuous return of the amplitude value back to the original starting condition. -If this change is graphically represented, then, there appears a wave-shaped curve of positive or negative trace, of which only the attained peak value can be characteristic for the coin. This peak value is in part not attained by other coins and in part exceeded by other coins. if an interrogation device is set to respond to a certain peak value, then those coins of a large class which do not greatly influence the amplitude are of no danger for the evaluation of a specific coin because its peak value is below the peak value of the coin to be checked. What is, however, dangerous for coin evaluation are those coins which notably influence the amplitude value. Their peak values are above the peak value of the coin to be checked, and consequently, each of these coins which has a considerable influence upon the checking operation generates, both when it moves into as well as out of the measuring location, an absolute magnitude which coincides with the peak value of the coins to be measured.
With the foregoing in mind, it should be readily apparent that the heretofore known electronic damping or attentuation measuring technique for travelling coins strives to overcome this difficulty. This is undertaken in that from a momentary amplitude curve there is only used for the evaluation technique the peak value, and the increasing and decreasing values which are generated during infeed and outfeed of the coins from the measuring device are suppressed. The solution of the prior art enables this to be done by having the coin actuate a contact as soon as it is exactly located in the measuring device. This contact triggers the checking or measuring operation, and specifically,only for a very short adjustable time span. ln this manner, it is ensured that only those portions of the curve envelope or trace of the ascending or descending values which are desirable for the checking or measuring operation are in fact measured, and which for themselves can be considered as characteristic of the class or type of coin, namely, the peak value of an assumed curve.
However, this known coin checking technique is associated with numerous drawbacks. It is here mentioned that while the extremely short periods of time which are available when a coin moves past and in front ofa measuring probe can indeed be effectively utilized, such still requires a certain expenditure of equipment if one is to exactly make use of these times in proper correlation with the through-passage speeds of the different coins. So that this measuring technique is constant, it requires a rather defined travelling speed for the coins. It is for that reason that the apparatus utilized in practicing this checking technique and which has become known to the art makes use of a vertical channel through which the coins drop under the influence of gravity. Experience has shown that the dropping velocity of the coins then is approximately constant. It is not necessary to take into account the different fall velocities of coins of different size and different weight, because this apparatus for the above-explained reasons only is equipped with one channel for one type or classification of coin, and can only be equipped with one channel, because no attempt is made for universal use of the equipment for a number of different classes of coins and such can not even be undertaken with such type of equipment.
A further drawback of this known technique is the following: the employed type of circuitry must be especially adjusted for each type of coin and for each measuring device in order to accommodate such in the most favorable way to the course or envelope of the curve and through-passage velocity of the relevant type of coin. Yet, this adjustment necessity engenders a substantial cost factor and renders more difficult manufacture of the equipment. Apart from the foregoing, it is impossible to exactly measure a number of different types of coins by means of one measuring system.
A further drawback of the known technique resides in the necessity of utilizing a switch. lf mechanical switches are used, it is necessary to contend with the difficulty of preventing their large specimen deviations or to overcome such through expensive adjustment operations. The utilization of electronic switches provokes a considerable cost problem, and adjustment operations are likewise not avoided. In any event, the use of the required switching elements makes manufacturing more difficult. Furthermore, the considerable cost for the use of a very exact timing element and the increased circuit design costs which are necessary in order to attain very short transient times during intermittent operation for the circuit, constitute further drawbacks of the prior art system.
SUMMARY OF THE INVENTION Accordingly, there is a real need in the art for an improved coin checking technique which is not associated with the aforementioned drawbacks of the prior art. Hence, a primary objective of the present invention is to provide just such improved coin checking technique which overcomes the aforementioned disadvantages of the heretofore known methods.
Another, more specific object of the present invention relates to an improved method for checking coins which is not associated with the aforementioned drawbacks of the prior art, and furthermore, permits universal application for an optional large number of coins of different diameter.
Still a further significant object of the present invention relates to an improved coin checking technique which is extremely reliable in operation, has great versatility insofar as it is capable of checking coins of different classes and denominations successfully and with complete integrity, and effectively safeguards against the improper use of false coins or coin types.
Now, in order to achieve these objectives the invention, first of all, does not rely upon the artificial suppression of the ascending and descending amplitude values, and, in contrast to the known solution, utilizes the entire existing amplitude curve or envelope for the evaluation and determination of the peak value. There is used a measuring device of optional construction or type which records the amplitude displacement, and thus, passes through all values between the starting point and the peak point and finally again the starting point. To determine a specific peak value, there are provided amplitude-responsive measuring thresholds. If, for instance, there is utilized a damping measurement or a voltage measurement, then, this requires the use ofa voltage threshold responsive device which can be adjusted to a predetermined voltage and thus to a predetermined response sensitivity. However, the use of a single voltage threshold device is not sufficient, because one such device is not capable of differentiating the coins to be measured exactly from similar coins or counterfit coins. It is a known fact, that numerous coins are sufficiently similar so that they are mistaken for one another. In many cases they have the same dimensions, are stamped from the same material and differ only in nuances. Hence, the value characteristic of a coin for a certain coin must therefore be very exactly defined if a sufficient differentiation is to be achieved.
it is for such reason that there is not merely em ployed a single voltage threshold device, rather two are utilized, one of which determines the minimum value and the other the maximum value of a permissible volt age. It is here mentioned that in the context of this application the determination of a voltage is only exemplary of one physical magnitude which can be determined when utilizing the inventive concepts.
According to a further aspect of the invention, both of these threshold values are then logically coupled and specifically in such a manner that by means of an AND- gate a signal is generated when exceeding one of both thresholds and upon passing through both thresholds there is engendered signal suppression.
According to a further concept of the invention these thresholds are designed such that their spacing from one another can be variably adjusted. in this way, it is possible to adjust and fix for different coins different band widths.
The inventive method is constituted such that during through-passage of different markedly influencing coins a pulse sequence appears which at most possesses two pulses. it should be clear that when fixing the previously described double threshold at a certain level, under certain circumstances, a coin which possesses characteristics which only slightly influence the prescribed measuring technique, does not cause crossover of any of the two thresholds and, in this case, no pulse signal occurs. This is one of the possible switching conditions.
Furthermore, it can be imagined that a coin passing through the measuring system exactly attains a desired voltage value within the prescribed band width and thus represents a correct or proper" coin. in this case, the peak value of the amplitude curve will exceed at one predetermined location the one threshold, so that between both thresholds this amplitude curve culminates, then drops and again passes through the threshold which previously was exceeded. During this entire time, there appears a signal which can be evaluated in the form of a pulse. There is thus obtained one pulse. This is the second possible switching condition or state.
Furthermore, it should be understood that for a coin which possesses strongly influencing characteristics, the measurement value thereof passes through both the one threshold as well as the other threshold. obtaining the maximum value above both thresholds, and when moving out of the measuring device flattens the mea surement value, which again passes through both thresholds and returns to the starting level. Such type curve generates two pulses. This occurs in the following manner: in passing through the first threshold, there appears a signal which can be evaluated and when always considering the ascending flank or line of the curve passing through the second threshold the aforedescribed AND-circuit is actuated and terminates the resulting signal. This signalle ss state continues in relation to the extent with which the amplitude value ascends past the double threshold and where it culminates. During the descending portion of this signal such again passes successively through both thresholds, and the circuitry herein employed causes the ap pearance once again of a pulse. This third possible switching condition is thus manifested by the presence of two pulses.
These three possible signal states (0, l or 2) are hereinafter referred to as "typical of the coin class or type, since no pulse or 2 pulses signifies an impro per coin type or group and 1 pulse the correct" type or group of coin.
At this point, it should be clear why circuits which at this point of time cooperate with a coin sorting branch or routing means cannot properly function. For instance, false or incorrect coins which possess properties tending to generate a pronounced dampening ac tion, produce two signals, which already during the presence of the first signal cause the coin to be classified as a proper or correct coin.
Since the typical pulse plot or graph either depicts a wide square wave pulse for a correct coin or two sharp spikes for a strongly damping false coin, so that it could he stated that an evaluation of the pulse width would lead to the conclusion that the one wide pulse ("proper" pulse) represents the receipt ofa correct coin, but the first of two spikes (improper" pulses) indicates the receipt of an incorrect coin. However, this interpretation is not correct because both measurement thresholds, the upper and the lower, must always delimit a coin class with all of its tolerances. On the one hand, the determination of both thresholds is dependent upon the closest types of coins and their voltage values which are typical or characteristic of such type coin, and, on the other hand, upon the desired acceptance accuracy. All coins of the relevant classification must be measured within the positionally defined window" or "field." Its individual deviation can therefore no longer be taken into account. Since, in addition to the exemplary deviations of the coins, there must also be considered the measurement technical factors, as well as the factors with regard to deviations in travelling speed of the coins, basically thus also such good" coins must be accepted which only bring about a brief passage of the peak value of an amplitude curve into the "window."
Since this brief passage can also occur for correct coins, a spike pulse can also appear for such correct coins. It therefore follows that the evaluation of the pulse width is not a suitable approach for differentiating between proper and improper coins.
Instead of the foregoing approach, the invention proposes undertaking a logical evaluation which dif ferentiates between 0 pulses or 2 pulses on the one hand, and 1 pulse on the other hand. One pulse signifies a correct" or "proper" coin, no or two pulses signifies an "improper" or false" coin.
This evaluation can be undertaken in accordance with the invention in different ways. For instance, it is advantageous to employ a bistable multi-vibrator (flipflop) or another equivalent type circuit arrangement which is characterized by the features that an incoming pulse causes it to assume one switching condition or state and a further incoming pulse removes such switching condition. From the given example, it will be clear that this circuit arrangement which should be employed for further processing the actual correct" signal either fails to respond at all (no pulse) or only responds for a very short period of time (two pulses) namely as a result of the first pulse, the effect of which is again removed by the shortly thereafter incoming second pulse. Hence, there is only required for the successive evaluation circuit a slight time-delay in order to suppress any possibly occurring "flickering. This can be, for instance, already provided when using a relay by virtue of the response delay which prevails automatically due to its physical structure, without having to resort to the use of special time-delay producing measures.
Only if one pulse appears (and this can only occur upon the passage of a correct or proper coin) is the circuit device brought into one switching state and remains in such for an optional amount of time.
According to a further aspect of the invention, it would be possible to utilize with particular advantage a counter for the evaluation of the very brief sequence of pulses, which, as previously mentioned, at most only contains two pulses. This two-stage counter can be, according to a further concept of the invention, ad vantageously designed as a buffer counter. Under the expression buffer counter" there is to be understood a capacitor counter which is incrementally charged by pulses, in other words, is brought up to a defined volt age level. The storage elements proposed by the invention bring about the transformation of "signals characteristic of the coin groups" into a Yes/No-response and the storage thereof until they are evaluated.
Advantageously, there may be provided a channel through which there can freely move the "improper or "incorrect" coins (which upon passing through the measuring device do not cause an employed storage element to assume a switching state which it retains until it is interrogated), in other words returns such improper coins. Only correct" coins which upon passing through the measuring path cause the storage element to assume a switching state, actuate a coin branch and are collected upon the interrogation of the stored result. Naturally, in special situations, it would be possible to undertake a reversed evaluation.
The inventive method of checking coins is generally manifested by the features that the electrical signals generated by the coins, and therefore classified as characteristic of the coin, which signals are produced from an indirect measurement, are at least partially stored, and upon completion of the measurement or checking of a coin the electrical signal is evaluated in such a way that it is determined whether the coin has or has not produced a signal characteristic thereof.
It is advantageous if a coin which is in movement is checked by means of at least one contactless measuringand evaluation circuit, wherein the voltage value typical of the coin, for instance the drop of an idling or no-load amplitude, and if desired is transformed into pulses typical of the coin classification, is transferred into a Yes/No-response and stored until it is evaluated. Furthermore, it is advantageous if the wave-shaped ascent and descent of the amplitude values resulting during the passage of the coins in front of a measuring location are used for the measurement of the peak value of one of each wave in such a way that a response threshold is provided above and below the desired peak value typical of the coin, which response threshold, if desired, can be adjusted with regard to its amplitude, and wherein both response threshold values are logically coupled with one another in such a manner that only the response of one threshold generates a signal, the response of both thresholds precludes the generation of a signal, and that therefore a pulse sequence resulting from exceeding one or both pulse thresholds, this pulse sequence being limited in this manner to a maximum of two pulses, is evaluated by means of a bistable multivibrator (flip-flop) or a similar and functionally equivalent mechanism, for instance a counter or a thyristor.
When utilizing a damping measuring technique, it is advantageous to rely upon the exceeding of the upper voltage threshold and only such with, if desired, adjustable time delay, for activating a sorting mechanism or the like, Further, exceeding of the second voltage threshold can be used to release a possible preparatory switching of the sorting mechanism or the like within the time-delay period, so that this time delay for switching or activating the sorting mechanism or the like is at least as large as the time required for passing through the upper and the lower voltage thresholds as a function of the speed of movement of the coins.
When using at least one measuring device for the determination of the genuiness of coins and a subsequently arranged electrically energizable collecting mechanism for certain coins, it is advantageous if the response of the collecting mechanism follows without delay and automatically the completed checking or measuring operation undertaken by the measurement device, and without using time-determining components.
DETAILED DESCRIPTION OF THE DRAWINGS:
The invention will be better understood and objects other than those set forth above, will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:
FIG. 1 is a schematic cross-sectional view through a measuring device depicting five assumed positions of a through passing coin;
FIG. 2 graphically illustrates the typical course of a curve for a certain coin, illustrating the absolute values corresponding to the five coin positions depicted in FIG. 1;
FIG. 3 graphically illustrates typical amplitude curves with the values for different coins and the tixa tion ofa double-threshold;
FIG. 4 graphically depicts the pulses, shown as square-wave pulses, resulting from these coins and the curve traces when using the inventive circuitry;
FIG. 5 is a block diagram of a preferred embodiment of apparatus used for the practice of the inventive coin checking method;
FIG. 6 illustrates for a certain coin the typical course of the curve and the persistance time of the absolute peak value as well as the flattening of the curve brought about by the mechanical blocking or arresting of the coin, which value however is without any significance for the actual measurement;
FIG. 7 shows the pulse sequence associated with the curve depicted in FIG. 6;
FIG. 8 is a block diagram ofa circuit arrangement for an electronic coin checking device utilizing an electronic yarn or thread cutter;"
FIG. 9 graphically illustrates damping curves and signals which appear when passing through a doublethreshold under favorable conditions;
FIG. 10 is the same graphic representation shown in FIG. 9, but this time in the presence of unfavorable conditions;
FIG. I] is a block diagram of the coin checking apparatus used in conjunction with the conditions depicted in FIGS. 9 and 10;
FIG. 12 is a block circuit diagram of a coin checking device for three different coins, using a system in which a signal produced by a correct coin is only then utilized for actuating a collecting device if an additional switch associated with the collecting device has closed an as sociated or corresponding current path;
FIGS. 13 and 13a show details of the arrangement of the control switch or circuit for the system of FIG. [2;
FIG. 14 is a block circuit diagram of a checking device for three different coins wherein there is re-used a no-load or idling amplitude for the actuation of the chute, which was lost during a measuring operation; and
FIGS. 15, 15a and 15b illustrate details of the block circuit diagram represented in FIG. I4.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:
Describing now the drawings, in FIG. 1 there is illustrated a coin channel 10 through which travel the individual coins, this channel I0 embodying a floor portion I] and an upper boundry wall l2. At the center of the channel 10, there is arranged a measuring probe 13 past which move the coins. The solid line coin position 14 represents that position where the coin generates the greatest influence, because in that position the coin is disposed exactly centrally with respect to the measuring probe [3. On the other hand, the phantom line positions I5 and 16 represent the location of the coin when entering into the measuring device, whereas the phan tom line positions 17 and 18 correspond to those positions of the coin upon departing from the measuring device.
FIG. 2 graphically depicts the starting amplitude 19, whereas reference numeral 20 graphically represents the amplitude change corresponding to the coin positions 18 and 15 of FIG. 1. Continuing, reference character 2| designates a corresponding amplitude in accordance with the coin positions 16 and 17 of FIG. I, and finally, reference character 22 designates the absolute peak value of the amplitude resulting when the coin assumes the position 14 of FIG. 1. As a matter of convenience, the coin positions 14 to 18 of FIG. I have again been depicted with the same reference numerals in FIG. 2. Additionally, reference characters 23 and 24 designate the portions of the curve-shaped peak value which can still be taken into consideration for the checking of a predetermined coin and which can be picked-out" of a known apparatus by means of the described contact construction.
FIG. 3 graphically represents the starting amplitude by reference character 25, whereas reference numerals 26, 27 and 28 designate the peak values of three different coins. It is to be assumed that the middle coin is to be checked, so that reference numerals 29 and 30 represent the double-threshold applied to both sides of the peak value 27. The curve shapes or envelopes for the three coins are indicated at 31, 32 and 33. As can be seen, the curve 31 does not reach the threshold 29 and thus does not generate any pulse. 0n the other hand, curve 32 passes at line 43 through the threshold 29 and departs from the threshold region again at line 45. The coin represented by the curve envelope 32 thus generates one pulse. Continuing, it will be observed that curve 33 passes through the threshold 29 at line 41 and passes through the threshold 30 at line 42. During this time span, a pulse appears. The curve 33 culminates at line 44 and when receding again passes through both thresholds at lines 46 and 47, where again a pulse appears.
The pulse graphs for the curves shown in FIG. 3 are plotted in FIG. 4. Hence, the lines 310, 320 and 330 designate the pulses corresponding to the curves 3l, 32 and 33 of FIG. 3.
Now, by referring to FIG. 4 more closely, it will be seen that at line 310 no pulse appears. On the other hand, line 320 clearly shows that between the lines 43 and 45 of FIG. 3 there appears a square-wave pulse 321. Furthermore, line 330 shows that between the lines 41 and 42 of FIG. 3, there appears a shorter square wave pulse 331 and between the lines 46 and 47 a second shorter square-wave or rectangular pulse 332.
FIG. 5 shows a block circuit diagram of an embodiment of coin checking apparatus. The coin is designated by reference numeral 101, the transmitter by reference numeral 102, the receiver by reference numeral 103. The coin placed between the transmitter 102 and the receiver 103 dampens the transmission power and therefore reduces the transmission energy arriving at the receiver 103. in other words, a starting or idling amplitude at the transmitter is attenuated to a certain maximum value by the coin placed between the transmitter 102 and the receiver 103.
The energy arriving at the receiver 103, which for instance is expressed in the form of a certain voltage value, is amplified at a subsequent arranged amplifier 104 to a level which can be evaluated. At the amplifier 104 the current path 141 leading to the potentiometers 105 and 107 branches. With the aid of both of these potentiometers 105 and 107 and the different adjustment thereof there can be achieved that the subsequently arranged Schmitt-Triggers 106 and 108, notwithstanding their similar response voltage, respond at different values. Both of the Schmitt-Triggers 106 and I08 thus form the previously mentioned doublethreshold. The previously mentioned signal inversion is brought about by the inversion or inverting amplifier 109. The AND-gate 110 logically couples both signals emanating from the Schmitt-Triggers 106 and 108 and renders them capable of being evaluated. The pulses which can be evaluated arrive via the current path ll] at the bistable multivibrator 112 which functions as a binary sealer. At this time it is mentioned that up to this point signals do not arrive if the coin I01 possesses too low a dampening value. in the event that the coins ll possess a greater dampening value than desired, then two pulses arrive at the bistable multivibrator or flip flop 112. Such then functions in the manner that it is placed into one switching state and by virtue of the next successive second pulse is again brought out of such switching state. In order to eliminate any possibly occurring flickering signal" a time-delay stage 113 is arranged after the flip-flop "2. This timedelay stage functions as a response delay mechanism. At the same time, if functions as a signal attenuator in order to provide an evaluatable length for the obtained signal which can only be derived from a correct" coin. The "correct signal formed by the time-delay stage 113 then can be directly evaluated in an evaluation stage M4, for instance a relay.
At this point, there is briefly mentioned the possible variation of the circuit arrangement which results if, in accordance with a further aspect of the invention, the coin is mechanically stopped at the location where it has attained its highest coin characteristic" damping value. In this case, the circuit in principle ends behind the AND-gate H0 at the current path 111, at which there either does or does not appear a signal. This signal can then, while dispensing with the flip-flop 112, but while retaining a suitable response delay by virtue of the timedelay element 113, be delivered to the evaluation device H4. This static interrogation therefore renders possible the dispensing with a structural component, namely the flip-flop 112. Furthermore, with this second embodiment it is also possible to dispense with the O-position of the flip-flop 112. While such has not been shown in greater detail in the block circuit diagram, such can be achieved quite easily in that the evaluation stage 114 (relay) brings about the O-position of the flipflop 112 through an appropriate contact.
H0. 6 illustrates an artificially expanded course of the amplitude curve. The idling or no-load amplitude is designated by reference character 25. Reference numeral 32 designates the curve of the amplitude value, and reference characters 29 and 30 designate an as sumed double-threshold. The absolute maximum value is indicated at 328. The lines and I60, specifically the spacing between such lines designates the duration of time during which the maximum value 328 is available for evaluation. This duration is practically unlimited and is dependent upon the design of the release control mechanism.
FIG. 7 illustrates the configuration of the corresponding pulse. Here again, the idling amplitude is indicated at 25, the maximum value at 328. Reference numeral 329 indicates the presence of the pulse, 330 the decay of the pulse. The lines 329 and 330 correspond to the points of H6. 6 at which the curve 32 passes through the first threshold 29.
The path designates the length of the prevailing maximum value of the amplitude curve which is delimited by the lines I50 and 160. However, for the evaluation, the path 170 is not decisive, rather the path 328 delimited by the lines 329 and 330.
What has been previously stated for the first doublethreshold with subsequent signal conversion and storage is applicable in the same degree for a second version of a voltage detector for measuring travelling coins, as such has been described hereinafter in conjunction with FIG. 8.
In this instance there is proposed a voltage discriminator which possesses a similar switching behavior, but is cheaper. A further objective is to render such voltage discriminator fool proof against manipulations which can be undertaken by coins suspended at threads and moved back and forth a number of times in the coin checking device. When this is done, mechanical coin checkers with serially arranged electrical contacts and also electronic coin checkers equipped with contactless operating measuring probes can be outwitted. Thus, when the coin is suspended on a string or thread it is possible to generate as many pulses as desired by means of only one actual or real coin, and therefore, possible to simulate the condition of a randomly high number of actual or real coins being deposited into the mechanism. Hence, to safeguard against such manipulations a number of mechanical and electronic coin checkers are equipped with so'called thread or string cutters." These devices which are intended to cut a thread are to a large part quite complicated and expensive in construction and readily subject to breakdown. Hence, a further aspect of the invention is to propose, instead of the use of such type equipment, a simple and fool-proof electronic solution. Accordingly, a further object of the invention is to combine both of these purposes by a means of a single circuit.
According to the invention, there is not formed as a voltage discriminator a so-called window circuit from two voltage-sensitive thresholds (for instance two Schmitt Triggers) rather as the voltage discriminator there is used only a single transistor. For this purpose, there is made use of the behavior of an optional transistor in the range of saturation and blocking on the one hand, and the so-called A-operation on the other hand.
As a rule, there is obtained a rectified output amplitude from a receiver circuit. According to the invention a high frequency voltage of lesser amplitude is superimposed upon this rectified output amplitude, which voltage, in turn, is amplified by the transistor during its transition from saturation into blocking state and viceversa, so that when passing through the window high frequency signals appear at the collector of the transistor, which after being again rectified, can be utilized in known manner as pulse-shaped information for an evaluation.
The range of the A-operation is defined by the specific characteristics of the transistor. Thus, with the described circuitry it is possible to construct relative narrow windows, so that also a very critical recognition of individual coins or the like is easily possible. in certain case, however, it may be desirable to widen the window-width." According to a further concept of the invention, the range of such voltage discriminator, constructed from a single transistor is broadened by resorting to the use of a counter coupling circuit or through suitable selection of the amplitude of the superimposed high frequency voltage.
This circuit possesses considerable advantages, in contrast to other voltage discriminator circuits, especially for very difficult measurements or checking operations with very narrow window range over a wide temperature range. It is possible for the window" formed by the transistor to wander as a whole within a certain drift, but it will never occur, as in the case of windows formed of two thresholds, that because of different drift, the upper and lower thresholds cross one another.
According to the invention, the position ofa window within a certain voltage range, that is to say, the voltage related position of the A-region ofa transistor in a voltage discriminator, is fixed in that an auxilliary voltage is delivered to this voltage discriminator, and thus in the end analysis to the transistor. With the described circuit, it is possible to very easily employ the resulting flank steepness of the rectified high frequency-evaluation pulse for the determination of the through passage velocity of the coins.
in such case, there is measured the through-passage velocity of differing or different types of coins and the flank steepness or slope derived therefrom. While making use of a certain safety-factor deviation it will be possible in known manner to very easily ensure that coins which do not reach the necessary minimum travelling speed in a coin channel will not be evaluated even if they deliver a signal which is correct" insofar as the amplitude is concerned. Thus, there is required a certain flank steepness, which is not too slight and not too high, for the rectified high frequency evaluation pulse.
Experience has shown that it is practically impossible to simulate that travelling speed for coins suspended at a thread which are attained by coins which travel freely through a measuring channel within a coin checking device. Due to this simple circuit arrangement, there is ensured that it is impossible to employ manipulations for the purpose of outwitting the machine by suspending the coins at threads.
The basic construction of the inventive circuit suitable for this purpose will now be described in conjunction with FIG. 8. A coin 3 is shown between the transmitter l and the receiver (receiver coil) 2 which reduces the electromagnetic coupling between the transmitter and the receiver. A successively arranged amplifier 4 for current or voltage amplifies the remaining signal to a level which can be evaluated. This signal then arrives via the branching at two identical rectifiers 5 and 50 equipped with successively arranged filtering elements 6 and 60, respectively. Both of these branch circuits should be identical in the interest of temperature stability.
The filter elements 6 and 60 possess different filtertime constants: filter unit 6 possesses a short-time constant in the order of magnitude of several milliseconds, whereas filter unit 60 possesses a considerably longer time constant in the order of magnitude of several seconds.
A direct current voltage arrives at the base of the transistor 7, the amplitude of which is proportional to the coupling change between the transmitter 1 and the receiver 2 brought about the coin 3. At the emitter 7] of the transistor 70, there appears a stabilized voltage (stabilized over a period of time, preferably a time which is greater than the measuring time for a coin). This stabilized voltage is divided after the filter element 60 by means of a voltage divider 61 in such a way that it corresponds to the coin characteristic voltage appearing at the base of the transistor 7 at the time of maximum coupling damping by a predetermined coin. The base pre-biasing (U required for the specific transistor characteristics must be taken into consideration.
It is here to be parenthetically mentioned that in principle the transistor can also be controlled via its emitter without changing anything as far as the inventive concepts are concerned. By means of the conductor l0 and from the transmitter l a HF-voltage in the order of magnitude of several hundred millivolts is superimposed upon the voltage controlling the transistor 7. (In certain situations, superimposing can be dispensed with if the time-constant of the filter element 6, is chosen to be small enough that its residual ripple possesses the required amplitude).
Amplified HF-voltages are tapped off of the collector 72 which are delivered via the differentiation stage 9, 10 to the rectifier 11. The differentiation stage 9, 10, consists ofa capacitor 9 and a grounded resistor 10 and serves for coupling out the amplified high frequency as well as blocking the direct-current component.
Reference character 8 designates the load resistor (R,,) of the transistor 7. After the rectifier H the rectified pulse-shaped signal (no or two signals for a false" or "improper" coin; 1 signal for a proper or correct" coin) is delivered to a pulse amplifier 12 consisting of an integration element 120, an amplifyingand limiting circuit 121 and a differentiation element 122. The integrator I20 dampens the impulse voltage for pulses of too short duration in such a manner that there is not exceeded a prescribed fixed threshold voltage of the limiting and pulse preparing amplifier I21, and thus it does not deliver any positive response. This is the situation for excessive travelling speed of the coins. If the time-duration of the pulse is large enough, then the pulse or pulses are processed in the pulse amplifier 12] in such a manner that there results both a sufficiently high voltage as well as flank steepness required for controlling the flip-flop 13. The thus prepared pulses now pass through the differentiation element 122 which shapes the pulses in such a way that they are suitable for controlling the flip-flop 13, yet under the precondition that their flank steepness does not fall below a fixed minimum value. This is the safety factor against two slowly moving coins. in such a case, the pulse blocking is dampened in such a manner that it is no longer sufficient for controlling the flip-flop.
Although the illustrated block circuit diagram has a somewhat different construction then that heretofore described for reasons of circuit design, still it has the same functions andpurpose to transform peak values recognized as typical or characteristic of a coin into a signal sequence which is delivered to the flipflop arranged at the end of the chain, which once again,just as in the heretofore described circuitry, carries out differentiation of the signals typical ofa coin group and its transformation into Yes/No-responses and stores the Yes/No-responses.
Continuing, the hereinafter described third species of threshold value detector likewise has the same function as both of the heretofore described threshold value circuits, which also can be utilized when employing comparative checking techniques. Also, this third species is capable of solving the typical checking or measuring problem during the checking of moving coins, namely that certain "characteristic coin values or parameters" must be delimited at both sides and picked out."
When using absolute measuring techniques, this means that there must be determined whether the damping of the idling amplitude occurring under the influence of the coin has dropped to a fixed double threshold" and not transcended or moved past same.
When using a comparative measuring technique, this means that there must be determined whether -crossover or a slight deviation about the O-cross-over has been reached and in no instance a reversal of the starting phase position. In other words, it must be deter mined whether typical coin value" is within or without a prescribed tolerance.
Hereinafter there will be described the essential aspects initially only in conjunction with an example of an absolute measuring technique. However, it is here mentioned that the embodiments are analogously also applicable if there is utilized a comparison measuring technique.
One starts with the proposition that too slight damping in which the peak value of the damping curve remains above the prescribed double threshold does not cause response of the collecting mechanism for the correct" coins because the upper of both threshold values has not been crossed,
A lower dropping of the damping curve at which the peak value of the curve passes through the upper threshold is utilized as the criterium for the response of the coin collecting device. However, this response of the collecting device occurs with a time-delay. The time-delay which if desired, can be adjustable, but in principle is fixed, permits waiting to see whether after response of the upper threshold there is possibly a cross-over of the lower threshold. Such would be the case if the damping brought about by the coin is greater than that prescribed.
According to a further concept of the invention, cross-over of the lower of both switching thresholds is utilized to again remove the initiated excitation or actuation of the collecting device,
The same type of behavior substantially prevails during comparative measuring techniques. On the assumption that, for instance, there is used a differential amplifier, three different signal conditions can prevail:
a. the brought about damping value is too small: the
starting phase condition remains;
the brought about damping value reaches the expected value: a 0-cross-over occurs; and
c. the brought about damping value is greater than that prescribed: when the coin enters into the mea suring device there occurs a reversal of the phase position and when moving again out of the measuring device there occurs the starting phase position.
At this time, it is mentioned that in the subsequent description, there is assumed the checking of travelling coins. A circuit modification and the simplification thereof which can be undertaken during checking of stationary or static coins will be apparent from the subsequent description and can be derived from the inventive concepts in known manner.
Now in FIG. 9, there is illustrated the upper threshold by reference character 10, the lower threshold by reference character ll. Three typical signal curves are illustrated at l2: l3 and 14, the corresponding base lines for the illustration of the signals are indicated at 100, 200 and 300.
Reference numerals 15 to 21 inclusive designate the connection lines which connect the cross-over points of the damping curves l2, l3 and I4 and the doublethresholds 10, H with the signal diagrams.
By referring to FIG. 9, it will be seen that the course of the damping curve 12 is not critical. It is immaterial for evaluation whether the curve [2 does or does not closely approach the upper threshold to. in no case is there any response of the evaluation circuit, as such will be recognized by the base line I00.
The same holds true for the course of the damping curve l4 which passes through both thresholds l0 and 11. It is immaterial whether the peak value of the curve 14 only slightly passes below the second threshold or clearly drops below the second threshold ll. It is only necessary for the function of the evaluation circuit that the second threshold has been passed, even if it is only briefly. Even in this instance there appears a short switching flank which, according to the invention, can be utilized for extinguishing a signal resulting from cross-over of the upper voltage threshold l0v FIG. 9 initially depicts the course of the curve 13 in ideal fashion wherein the peak value is located between both thresholds 10 and II. With this shape of the curve I3, there occurs the pulse length associated with the base line 200 and defined by the spacing between the vertically extending lines 17 and i9.
From the illustration there will further be recognized the deviation of the necessary delay time corresponding to the time which can prevail upon passing through both voltage thresholds and which corresponds to the spacing of the lines l5 and [6. This time is designated as the "immersion" time.
In the case of the curve [4 the crossover of the upper threshold is initially used for triggering a collecting mechanism or device, but a response delay is provided which at least is so large as the immersion"time to be expected. Within this time, however, also the second threshold is crossed, so that the prepared switching operation is suppressed.
in the case of the curve 13, this means that a certain time span is lost as delay time for the pulse length which is designated by the lines 17 and 19. This time span is defined by the spacing between the lines 17 and 18, corresponding to the spacing of the lines 15 and 16. The remaining residual time between the lines 18 and 19 constitutes the time remaining for the response of the collecting mechanism. However, this time increasingly diminishes in the same degree as the course of the curve 13 approaches the threshold with its apex value. if damping by the coin is only so slight that the threshold value 10 is only slightly passed, then, the time between the lines 17 and 19 is so small that from the entire time, after subtraction of the delay time, there remains a residual time which no longer is sufficient for response or activation of the collecting device.
Upon further approach of the peak value at the threshold value 10 the length of the pulse brought about by the presence of a proper coin can be smaller than the most finely adjusted delay time, as such can be derived from the spacing between the lines and 16.
FIG. 10 illustrates this unfavorable condition. What was previously stated for the course of the curves also is applicable in this example.
However, it will be apparent that the very short pulse brought about by the curve 13 is not sufficient for taking into account a time delay and the successive possible response of the collecting device.
it is for this reason that one cannot start with the premise that a simpler trigger will be sufficient for all conditions encountered in the illustrated circuitry. Therefore, it is to be recommended to use a monostable trigger instead of a standard trigger. This monostable trigger forms a short pulse into a pulse of a certain length, and therefore, also permits the proper evaluation ofa correct" pulse from an unfavorable condition as represented in FIG. 10. Only by using a monostable trigger instead of a standard trigger it is possible to avoid that a coin which has crossed over the threshold 10 and therefore is to be considered as a proper" coin, would be rejected because of an unfavorable, shorter pulse shape, even though it has brought about a crossover of the upper threshold which is considered as the criteria for the classification of a correct or proper coin.
A further improvement can be obtained if the upper threshold is neither constituted by a trigger nor a monostable trigger, rather by a bistable sweep stage, preferably formed by a thyristor. A thyristor possesses a very stable operating point and can readily assume bistable functions. Thus, there can be used the charac' teristic that once the thyristor has been switched in and even if it is only by a very brief or short pulse, it retains its switched state. The threshold 11 therefore cannot influence the operating point, because the gate of the thyristor is decoupled from the second threshold by means of an impedance converter, constituting a further aspect of the invention.
The use of a thyristor not only for the upper threshold 10, also for the lower threshold 11 instead of a trigger is not possible because of the absence of a resetting possibility for the thyristor at the threshold ll. One would then have to resort to the switch-off surge of the magnet of the collecting device for resetting the thyristor at the switching threshold 11.
FIG. 11 illustrates a block circuit diagram of an apparatus useful for the practice of the inventive method and incorporating a thyristor. The transmitter 22 trans mits to the receiver 24 an idling or no-load amplitude ofa certain magnitude. This amplitude is dampened by a coin 23 placed between the transmitter 22 and the receiver 24. The idling or dampened signal is amplified by amplifier 25, then delivered to two threshold devices 26 and 27. The drop of the idling amplitude level to a value predetermined by the threshold device 26 is utilized for switching a thyristor 28. The switching function of the thyristor 28 is delayed by a time delay element 29 and after completion of this time delay period such switching function is limited by a timing element 30. The subsequently arranged power amplifier 31 serves to amplify the signal and delivers such to the magnet 32 of a collecting device and also to interruption mechanism 33. This interruption mechanism or device 33 interrupts the input to the amplifier 25 via the conductor 34, so that during the period of time that the collecting device 32 is in operation no new measurements or checking operations need be taken into account.
The threshold value device 27, operated simultaneously with the threshold value device 26, responds when the dampening signal has exceeded a predetermined maximum value. It then actuates the trigger mechanism 35 which extinguishes the thyristor 28 via the conductor 36. However, since the time-wise spacing of the switching of the threshold value devices 26 and 27 is dependent upon the spacing of the threshold values from one another and upon the through-passage velocity of the coins as well as upon the absolute magnitude of the damping, a delay time is produced which corresponds to the maximum possible time-wise spacing of the excitation of the threshold value devices 26 and 27. This time constant is the time at least taken into account by the timing element 29. The other timing element 30 defines a time period necessary for the response of the collecting device 32.
it is here mentioned that the coupling of both timing elements 29 and 30 into a common timing element can be undertaken, which then by means of the same RC- components controls both time periods, namely the delay time for the response of the collecting device and the actuation time for the operation of the collecting device. However, the combining of both timing elements is then only possible when working with a coin checking device for a single class of type of coin.
When utilizing a coin checking device for different types or classes of coins it is necessary to provide separate timing elements 29 and 30. The timing element 2) is associated with the operation of the thyristor 28. in FIG. ll the functional units or components which need to be separately provided during the construction of a coin checking device for multiple types of coins, have been enclosed within the box or block 37. A number of these functional blocks for evaluating in each instance a certain type or class of coin can be electrically coupled together in known manner, for instance in that their outputs are connected via an OR- gate or the like with the timing stage 30.
It is a characteristic feature of this inventive solution that in the instant situation the thyristor employed as a threshold value-switch simultaneously serves as a storage element and the trigger used for the other threshold does not permit the appearance of the signal constituted by two pulses (pronounced damping by virtue of an improper coin) owing to its extinguishing function.
Further, it is mentioned that during the measuring or checking of travelling coins the switching hysteresis of the trigger 35 for the threshold device 27 must be taken into account and used in the circuit. This hysteresis must be dimensioned by means of certain circuit techniques in such a manner that it is greater than the threshold width, that is to say, the voltage differential between the threshold devices 26 and 27. With the inventive arrangement under consideration there can be achieved that the extinguishing effect of the trigger 35 via the conductor 36 at the thyristor 28 remains until the voltage level has dropped below a value no longer sufficient for ignition of the thyristor. If use is not made of this effect or if there is consciously permitted a certain hysteresis of the trigger, then, depending upon the characteristics of the coins, signals will result (0, l or 2) which must be counted-out" in the aforedescribed manner. This can, however, be suppressed by the appropriate construction of the previously described in ventive thyristor threshold.
The trigger suppresses the thyristor owing to its extinguishing function until the amplitude change has again de-parted from the range of the window and the thyristor does not again ignite. The thyristor itself stores a correct"-signal in the event that it is excited until evaluation and an extinguishing and therefore assumes both a measuring as well as a storage function.
The preceding embodiments related to the use of storage elements for attaining or obtaining Yes/Noresponses in measuring and evaluation circuits which relate to the evaluation of analog amplitude changes.
Mention is, however, made of the fact that numerous other operations which are required of a coin checking device, likewise necessitate the use of storage elements or the use thereof has been found to be particularly advantageous.
This is particularly true to a large extent if, in addition to the proper-improper-recognition of the coins, it is necessary to also undertake qualitative determinations, whether it be for a sorting of the coins according to their type by means ofa plurality of chutes controllable in accordance with the classification of the coins or their types or for the switching of current paths leading to counters in accordance with the coin class or type or for the control of pulse multipliers, and so forth in accordance with the class or type of coin.
Hereinafter, there are initially made certain basic observations for the interrogation of stored signals. It is presupposed that previously only electronic single type coin checking devices have been known and that such do not operate in accordance with the inventive solutions.
Electronic coin checking devices in which different coins can be checked preferably by means of a single measuring location in a single coin channel, are not known. Yet, it isjust such type of coin checking devices which in practice are of extensive importance.
Suitable proposals as to how to carry out the electronic checking of the coins and depending upon the results of such checking operations to collect or reject such coins and for this purpose to retain or seize the coins, have not been previously made nor known.
The hereinafter discussed invention has for its objec tive to propose special techniques and circuits for electrical or electronically operating singleor multipletype coin checking devices which enable a positive reception or return of the checked coins.
It is initially mentioned that coin checking devices of the aforementioned type can be constructed in a number of different ways. For instance, they can be provided with only a single measuring probe in one uniform coin channel provided for all of the coins and which serves to measure all coins. This will be regularly the case if only a single type of coin should be checked, but the apparatus can be adjusted for other coin types.
However. it is also conceivable to provide only a single coin channel for a coin checking device serving to check a number of different classes or types of coins and to arrange within this coin channel a number of measuring probes behind one another. Of each of these probes, one only has the function of checking a certain type of coin or a group of coin types. The invention therefore is concerned with proposing circuits which enable the random arrangement of one or a number of measuring probes, without this leading to an unwieldy design of the basic circuitry. This universality of the construction of a certain circuit for the collection of checked coins, whether one or a number of measuring probes are used, has considerable importance as far as fabrication of the equipment is concerned.
During the explanation of the invention concepts, it is possible to leave out of consideration whether in such an electronic coin checking device the coins to be checked are initially stopped and then one of two chutes releases the coins and directs such in a predetermined direction, or whether the coins are measured during free through-passage, whereby with a negative checking result such coins automatically again are discharged out of the checking device and in the case ofa positive checking result are collected by means of a chute or the like, or whether the reversed technique is chosen in which the coins in the event that they are properly checked travel through the coin channel into a collecting box and only the false coins are collected by a chute and deflected back. The decision for one of the three possibilities is determined on the basis of the method to be chosen and, moreover, will be dependent upon practical requirements.
During the explanation of the inventive concepts one can likewise leave out of consideration the determinations that the same considerations with regard to a multiple coin type-checking device in principle are also decisive for a single coin typechecking device.
For this reason. there will be discussed the circuit for instance for a multiple coin type-coin checking device which checks a number of coins in a single coin chan nel; furthermore, it will be assumed that coins where there appears a negative examination or checking result are automatically returned and only coins which have been determined to be correct are collected by means of an electrically excitable branch circuit. However, it is mentioned that solutions which deviate from the description of the invention given hereinafter but which still fall or are embraced by the general inventive concepts are equally possible.
Initially, there will be discussed which requirements are placed upon such a control and which criteria are decisive for the determination of their reliability. Assuming that coins of different size, different weight, coins formed of different materials and possessing different surface characteristics, and furthermore, pos sessing different degrees of contamination, pass through a coin channel, and assuming that this coin channel is not absolutely vertical, rather is at an inclination, then it will be clear that these coins possess different travelling speeds.
If there is considered the fact that a branch'off or side tracking control for collecting the correct coins is arranged at a certain spacing from a measuring probe in the direction of travel of the coins, then, by virtue of the different travelling speeds of the coins, a different length of time prevails for passing the measuring location until reaching the branch-off or divider location for the coins.
Furthermore, it must be kept in mind that a damping measurement, broadly speaking, already for reasons of economy, would be of use for application in an electronic coin checking device. This damping measurement is characterized by the features that a coin travelling past and in front of a measuring probe or between a pair of measuring probes will dampen an idling or no-load amplitude because of its specific properties and will produce a certain voltage level for a short period of time because of its through-passage. This transition from the idling amplitude to the coin characteristic-voltage level does not, however, occur suddenly. Rather, it occurs through a gradual reduction of the starting amplitude and a slow renewed increase thereof, after the coin characteristic-voltage value has been reached. This voltage change can be expressed in the form ofa curve as a function of the through-passage velocity of the coin and therefore of its throughpassage time, the flank portions of such curve being more or less steep. Such is not only dependent upon the damping characteristics of the coin which are a function of the material, but also of its diameter.
If different times result for the passage of the coin through the path from the center of the measuring probe until the beginning of the branch-off location already because of the different travelling speeds of the coins, then a further differentiation occurs because the different types of coins excite for a different length of time, even if they have the same travelling speed, the measuring probe passed by such coins. Hence, in coin checking devices which are supposed to check different coins by means of a measuring probe, the displacements, under certain circumstances, are of importance. To this there must be taken into account the fact that the coins possess a different degree of contamination and it is not possible to attribute to a certain type of coin a defined through-passage velocity or through-passage time.
Thus, if one starts with the assumption that there is provided a predetermined response time period to a coin branch-off device arranged at a certain spacing from the measuring probe and controlled by a timing element, then such arrangement would not be satisfactory because of the different types of operating conditions which would be encountered as previously explained above. Indeed, such arragement would regularly ensure that the branch-off device for the coins would respond soon enough when the coin which travels the quickest and has the smallest braking effect passes the measuring arrangement. However, this early response of the branch-off device by a correspondingly briefly calculated response time of the timing element would result in an unreliable operation of the apparatus in the instances where a coin moves particularly slowly through the apparatus. When this happens, the branchoff device for the coins would again be returned back into its starting position before the coin arrived, and therefore, the intended sorting effect would not be reached at all. Even more detrimental is the fact that the branch-off device would already respond at a period of time in which the measurement itself has not even been completed. The response of the branch-off device with incomplete measurement results would regularly lead to false classification or sorting. However, with the inventive construction of circuitry it is ensured that initially the measurement itself must be terminated before the response of the branch-off device can be undertaken, and furthermore, while taking into account the different through-passage velocities of the individual coins, the response of the branchoff device will only then occur when the quickly or slowly moving coins are located directly in front of the branch-off device.
in other words, the invention takes into account the different through-passage velocities of the coins, determines the completed measuring or checking of the coins in front of the measuring probes in a positive fashion, and on the other hand, enables the response of a coin branch-off device to occur at the earliest possible time and in the closet interrelationship with the measuring device. Consequently, as a whole, there is ensured for a very rapid reaction of the installation, leading to positive operation thereof even when coins are processed which travel rapidly behind one another.
As a result, the conventional technique of directly controlling a coin branch-off device by the measuring location is not employed, rather instead of such, the invention contemplates an intermediate storage of the Yes/No-response with a subsequent evaluation.
This specific solution becomes necessary by virtue of the objective of the invention of avoiding the use where possible of time-delay elements, and especially when considering the inventive objective of attempting to measure a number of coin types by means of only one measuring location. This makes of necessity the use of storage components. Hence, it is for such reason that the measurement results are stored until there is a completion of all of the measurement operations and the thereafter occurring interrogation operations.
According to the invention, there is preferably utilized a positive control. The operation time of the coin branch-off device itself, calculated from the period of time of its excitation until completion of the sorting function, can be, however, determined in known manner by means ofa timing element. This time is relatively non-critical, because the coins of different