CA1038055A - Coin arrival sensor using inductive colls - Google Patents
Coin arrival sensor using inductive collsInfo
- Publication number
- CA1038055A CA1038055A CA214,346A CA214346A CA1038055A CA 1038055 A CA1038055 A CA 1038055A CA 214346 A CA214346 A CA 214346A CA 1038055 A CA1038055 A CA 1038055A
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- Canada
- Prior art keywords
- coin
- output signal
- comparator
- signal
- reference signal
- Prior art date
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Classifications
-
- G—PHYSICS
- G07—CHECKING-DEVICES
- G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
- G07D5/00—Testing specially adapted to determine the identity or genuineness of coins, e.g. for segregating coins which are unacceptable or alien to a currency
- G07D5/08—Testing the magnetic or electric properties
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Testing Of Coins (AREA)
- Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
- Switches That Are Operated By Magnetic Or Electric Fields (AREA)
- Control Of Vending Devices And Auxiliary Devices For Vending Devices (AREA)
Abstract
COIN ARRIVAL SENSOR
ABSTRACT
Apparatus for sensing the arrival of a coin in coin handling mechanisms and producing an output signal only if the coin is of an acceptable type of material. The coin is placed between transmitting and receiving coils.
The transmitting coil produces an oscillating magnetic field with components of different frequencies. The amplitudes of the components of the two different frequencies are examined and if they correspond to the amplitudes for an acceptable type of material, e.g. . conductive non-ferromagnetic, the apparatus indicates the arrival of a coin.
ABSTRACT
Apparatus for sensing the arrival of a coin in coin handling mechanisms and producing an output signal only if the coin is of an acceptable type of material. The coin is placed between transmitting and receiving coils.
The transmitting coil produces an oscillating magnetic field with components of different frequencies. The amplitudes of the components of the two different frequencies are examined and if they correspond to the amplitudes for an acceptable type of material, e.g. . conductive non-ferromagnetic, the apparatus indicates the arrival of a coin.
Description
This invention relates to coin handling mechanisms t:e.g. for use in coin-operated vending machines), and especially to apparatus for sensing the arrival of a coin in a coln handling mechanIsm and for initiating a coin-identifying operation if the coin is of an acceptable type of material.
In some of the more advanced types of coin handling mechanisms such as, for example, mechanisms in which coins are authenticated by electronic or photo-electronic means, it is useful to have apparatus for sensing the arrival of a coin in the mechanism to ac~ivate the coln identifying apparatus and initiate a sequence of coin-identifying operations. For example, in a mechanism for determining the authenticity and/or denominations of coins whlch u~e~ optical sen~inS means such as photo-electric cells with associated llght sources, it ls desirable to have the light sources turned on only while a coin is being processed by the mechanlsm, slnce this greatly extends the life of the light sources. It is preferable that the coin arrival sensar not be an optical sensor, since an optical sensor would necessitate another light source which would have to be turned on all the time. Furthermore, since optical coin-identifying systems cannot directl~y check the material of a coin, the coin arrival sensor is preferably one which determined whether the coin is of an acceptable material or an acceptable type of material.
According to the present inventlon there is provided apparatus for sensing the arrival of a coin ln a coin handling mechanlsm and for producing an output slgnal when the coin i9 oE an acceptable type of material comprising: transmitting means including at least one transmitting inductor, for generating an oscillatIng magnetic ~Ield havIng components of two substantially different frequencies; receiving means including at least one receiving inductor disposed in the magnetic field produced by ~0380S5 said transmitting means, for detecting the amplitude of said co~ponents at the location of saîd receiving inductor; means ~or guiding a coin between the transmitting and receiving inductors so that a substantial portion of the magnetic energy received by said receiving inductor is transmitted through the coin; and means for comparing the amplitudes of the components detected by the receiving means with the corresponding amplitudes for coins of an acceptable type of material and for producing an output si~nal indicative o~ the arrival of a coin of an acceptable type of material when the detected amplitudes of both components correspond substantially to the ampli~udes for a coin o~ an acceptable type of materlal.
The transmittlng inductor radiates magnetlc energy at two substantially different frequencies. This energy induces electrical signals of corresponding frequencies in the receiving inductor located opposite the transmitting inductor. A CoiD
introduced into the coin handling mechanism is guided between the transmitting and receiving inductors so that a substantial portion of the energy propagating from the transmitting inductor to the receiving inductor passes through the coin. This affects the amount of energy received by the receiving inductor (and therefore the amplitudes of the signals induced therein) to a degree dependent on the material of the coin and the frequencies transmitted.
Thus, the apparatus of the present invention employs an osclllating magnetic field to determine the arrival of a coin ~ithin the coin handling mechanism. In addition to sensing the arrival o~ a coin, this coin arri~al sensor e~amines the material o~ the coin as a preliminary test o~ coin authenticity. Since most of ~he world's genuine coins are made o~ conductive, non-ferromagnetic materials (e.g. copper, cupro-nickel, etc.), the ~031~0S$
arrival sensing apparatus may be arranged to produce the output signal only for the arrival of conductive, non-ferromagnetic coins only, thus eliminating many types o$ slugs (e.g. non-conductive slugs such as paper, plastic, and $erromagnetic slugs such as iron, steel, and ferrites) from consideration by the coin handling mechanism. For those countries where genuine coins are of other materials (e.g. ferromagnetic~, the arrival sensing apparatus will be arranged to indicate the arrival of coins of this type of material.
With regard to the choice of the two substantially different frequencies, a first relatively low frequency i9 ChQSell 80 that ferromagnetic materlals have a considerably greater ef$ect on the amplitude o$ the tran~mltted electromagnetlc energy at that frequency than non-magnetic materials. A second relative high $requency i6 chosen so that conductive materials, and ~
particularly all acceptable coins of conductive materials, have a readily detectable effect on ~380S~;i the amplitude of transmitted electromagnetic energy at that frequency. Accordingly, the arrival of a conductive, non-magnetic coin, for example, is indicated by a signi~icant decrease in the amplitude of the high frequency signal induced in the receiving inductor together with a decrease in the amplitude of the low frequency signal less significant than the decrease that would indicate a magnetic material.
In accordance with one aspect of the present invention there .is provided apparatus for sensing the arrival of a coin in a coin handling mechanism and for producing an output signal when the coin is of an acceptable type of material comprising: transmitting means including at lcast one transmitting inductor, for gencrating an oscillating magnetic field havlng components Oe two substant:ially difeerent frequencies; receiving means including at least one receiving inductor disposed in the magnetic field produced by said transmitting means for detecting the amplitude of said components at the location of said receiving inductor; means for guiding a coin between the transmitting
In some of the more advanced types of coin handling mechanisms such as, for example, mechanisms in which coins are authenticated by electronic or photo-electronic means, it is useful to have apparatus for sensing the arrival of a coin in the mechanism to ac~ivate the coln identifying apparatus and initiate a sequence of coin-identifying operations. For example, in a mechanism for determining the authenticity and/or denominations of coins whlch u~e~ optical sen~inS means such as photo-electric cells with associated llght sources, it ls desirable to have the light sources turned on only while a coin is being processed by the mechanlsm, slnce this greatly extends the life of the light sources. It is preferable that the coin arrival sensar not be an optical sensor, since an optical sensor would necessitate another light source which would have to be turned on all the time. Furthermore, since optical coin-identifying systems cannot directl~y check the material of a coin, the coin arrival sensor is preferably one which determined whether the coin is of an acceptable material or an acceptable type of material.
According to the present inventlon there is provided apparatus for sensing the arrival of a coin ln a coin handling mechanlsm and for producing an output slgnal when the coin i9 oE an acceptable type of material comprising: transmitting means including at least one transmitting inductor, for generating an oscillatIng magnetic ~Ield havIng components of two substantially different frequencies; receiving means including at least one receiving inductor disposed in the magnetic field produced by ~0380S5 said transmitting means, for detecting the amplitude of said co~ponents at the location of saîd receiving inductor; means ~or guiding a coin between the transmitting and receiving inductors so that a substantial portion of the magnetic energy received by said receiving inductor is transmitted through the coin; and means for comparing the amplitudes of the components detected by the receiving means with the corresponding amplitudes for coins of an acceptable type of material and for producing an output si~nal indicative o~ the arrival of a coin of an acceptable type of material when the detected amplitudes of both components correspond substantially to the ampli~udes for a coin o~ an acceptable type of materlal.
The transmittlng inductor radiates magnetlc energy at two substantially different frequencies. This energy induces electrical signals of corresponding frequencies in the receiving inductor located opposite the transmitting inductor. A CoiD
introduced into the coin handling mechanism is guided between the transmitting and receiving inductors so that a substantial portion of the energy propagating from the transmitting inductor to the receiving inductor passes through the coin. This affects the amount of energy received by the receiving inductor (and therefore the amplitudes of the signals induced therein) to a degree dependent on the material of the coin and the frequencies transmitted.
Thus, the apparatus of the present invention employs an osclllating magnetic field to determine the arrival of a coin ~ithin the coin handling mechanism. In addition to sensing the arrival o~ a coin, this coin arri~al sensor e~amines the material o~ the coin as a preliminary test o~ coin authenticity. Since most of ~he world's genuine coins are made o~ conductive, non-ferromagnetic materials (e.g. copper, cupro-nickel, etc.), the ~031~0S$
arrival sensing apparatus may be arranged to produce the output signal only for the arrival of conductive, non-ferromagnetic coins only, thus eliminating many types o$ slugs (e.g. non-conductive slugs such as paper, plastic, and $erromagnetic slugs such as iron, steel, and ferrites) from consideration by the coin handling mechanism. For those countries where genuine coins are of other materials (e.g. ferromagnetic~, the arrival sensing apparatus will be arranged to indicate the arrival of coins of this type of material.
With regard to the choice of the two substantially different frequencies, a first relatively low frequency i9 ChQSell 80 that ferromagnetic materlals have a considerably greater ef$ect on the amplitude o$ the tran~mltted electromagnetlc energy at that frequency than non-magnetic materials. A second relative high $requency i6 chosen so that conductive materials, and ~
particularly all acceptable coins of conductive materials, have a readily detectable effect on ~380S~;i the amplitude of transmitted electromagnetic energy at that frequency. Accordingly, the arrival of a conductive, non-magnetic coin, for example, is indicated by a signi~icant decrease in the amplitude of the high frequency signal induced in the receiving inductor together with a decrease in the amplitude of the low frequency signal less significant than the decrease that would indicate a magnetic material.
In accordance with one aspect of the present invention there .is provided apparatus for sensing the arrival of a coin in a coin handling mechanism and for producing an output signal when the coin is of an acceptable type of material comprising: transmitting means including at lcast one transmitting inductor, for gencrating an oscillating magnetic field havlng components Oe two substant:ially difeerent frequencies; receiving means including at least one receiving inductor disposed in the magnetic field produced by said transmitting means for detecting the amplitude of said components at the location of said receiving inductor; means for guiding a coin between the transmitting
2~ and receiving inductors so that a substantial portion of the magnetic energy received by said receiving inductor is transmitted through the coin; and separate means for comparin~
each of the amplitudes of the components detected by the receiving means with the corresponding amplitude for coins of an acceptable type of material and for producing an output signal inclicative o the arrival o a coin of an acceptable type of material when the detected amplitudes of each of the components corresponds substantially to the corresponding amplitudes for a coin of an acceptable type of material.
Embodiments of the invention will now be described, by ~ - 5 -~1~3~ i5 way of example, with reference to the accompanying drawings, in which:-Figure 1 is a front view of a portion of a coin handlingmechanism showing one possible location for the inductors of a coin arrival sensor according to the present invention;
Figure 2 is a sectional view taken along the line 2-2 in Figure 1 with a schematic block diagram of the coin arrival sensor;
Figure 3 is a detailed block diagram of one embodiment of circuitry for the arrival sensor of Figures 1 and 2;
Figures 4a to 4g are a series of signal traces, plotted against a common timo axis, useful i.n understanding the embodiment of Pigure 3;
Figure 5 is a dotailed block dia~raal o:~ a secon(l ombodimont of circuitry for the arrival sensor oE Figures 1 and 2;
Figures 6a to 6g are a series of signal traces, plotted against a common time axis, useful in understanding the embodiment of Figure 5;
,, ~
~38~5~i Figure 7 i8 a detalled block diagram o~ a third embodi~ent o~ circuitry for the arrival sensor of Figures l and 2;
Pigures 8a to 8d are a series of 8ignal traces, plotted agains~ a common time axis, u~eful in understanding the embodiment o~ F:Lgure 7.
Throughout this speci1cation and in the appended claims, the ~erm "coin" i8 intended to mean genuine coins, tokens, counterfeit coins, slugs, washers, and any other item which may be used by persons in an attempt to use coin-operated devices.
In the coin handling device lO shown in Figures 1 and 2, a coin enters the device throu~h a coin entry 12 and falls edge first onto the initial portion oE a coin track 20 between parnllel Eront and back plates 14 nnd 16. The coln rol.l~ down thls portion of the coin track 20, coming to rest in the position shown by dotted line 24 against a coin start gate 22. In this position the coin is between transmitting and receiving inductors 32 and 34 of a coin arrival sensor 30 according to the present invention. The inductors 32 and 34 are mounted opposite one another on the plates 14 and 16, respectively. The inductors 32 and 34 are of such siæe and locatlon that when any coin acceptable to the device 10 is at rest against the coin start gate 22, substantially all of the electromagnetic energy ;
propagating from the i.nductor 32 to the inductor 34 passes through the coin.
When the arrival sensor 30 which include~ low and high ~requency power supplies 36 and 38 and a receiving circuit 40, detects a coin o an acceptable type of material between the inductors 32 and 34 as described in detail below, it produces an output signal applied to activate the start gate solenoid 42 and a coin identiEying circuit 44. In response, the start ~038(~S
gate solenoid retracts the start gate 22 into the back plate 16, allowing the coin to continue to roll down the coin track 20. When the coin identifying circuit 44 is activated, light sources associated with optical coin sensors 50 ~e.g. photoelectric devices~ are turned on. As the coin rolls down track 20 it passes the passage of the coln is sensed by the coin identifying circuit by means of the sensors 50. The coin identifying circu~t 44 determines whether or not the coin is acceptable, for example, by optically examining its velocity, diameter, etc., as disclosed in U.K. Patent Specificatian 1,272,560. ~t the end of coln track 20 the coin drop~ toward a coln acceptance gate 52. IE tha coln has been Ldentlfled as acceptable, the coln ac.~eptancc ~e 52 1B r~tracted lnto back plate l6 by a ~oLcno:ld (not ~hown) and the coin falls from the track 20 into a coln acceptance chute 54 leading to a coin box of the vending machine. If the coin is not recognised as acceptable, the coin acceptance gate 52 i9 not retracted and the coin falling from the end of the coin track 20 strikes the acceptance gate 52 and is diverted into a re~ect chute 56, which leads to a coin return window of the vending machine.
Figure 3 shows one form of the circuitry of the coin arrival sensor 30 of thiR invention including the low frequency power supply 36 and the high frequency power supply 38, aach of which is connected to a separate coil wound around the core of the transmitting lnductor 32. The low frequency power supply 36 produces an alternating current (a.c.) output signal having a first relatively low frequency (e.g. 50 or 60 Hz). The ultimate source of this signal may be mains. In that event, the power supply 36 may be a transformer for reducing the mains voltage to a safer level. The liigh frequency power supply 38 produces an a.c. output signal having a second relatively high ~333~ 5 ~requency (e.g. 70 KHz~. The power supply 38 may therefore be any suitable ~.c. signal generator, e.g. a square wave generator and a ~ilter for filtering the square wave to produce a sinusoidal signal.
As mentioned above, the a.c. output signal of each of the power supplies 36 and 3~ is applied to a separate coil on the core of the lnductor 32. Accordingly, the inductor 32 produces an alternating magnetic field which is the superposition of the alternating magnetic fields due to each of the applied a.c.
signals. This field radiates across the coin passageway above the coin track 20 in the apparatus of Flgures 1 and 2 and lnduces an a.c. electrlc~l slgnal ln the coll of the recelvLng :Lnductor 34. This lnduced slgnal ha~ frequ~ncy components correapondlng to the frequencles of the slgnals applled to the transmitting inductor 32. The output signal of the receiving inductor 34 is applled to low pass and high pass fllters 60 and 70 which separate the low and high frequency components of that signal.
The output signals of the low pass and high pass filters 60 and 70 are represented by the sinusoidal signal traces shown in Figures 4a and 4c, respectively. The p~rt~on of Figures 4a to 4g to the left of time line A-A represent the condition of the apparatus of Figure 3 priar to the arrival of a coin. For ease of illustration, the output signals of filters 60 and 70 are represented in Figures 4a and 4c as having frequencies much lower than is actually the case. Moreover, the output signal frequency of the filter 70 ls typically many tlmes greater than the output signal frequency of the ilter 60. At the time A-A, a conducti.ve, non-magnetic coin arrives in the apparatus between the inductors 32 and 34 and remalns there untll a time B-B when the coin start gate 22 is retracted. During the period indicated between lines B-B and C-C there is again no detectable object between the ~3805~
- inductors 32 and 34. At a ti~e C-C a magnetic coin arrives in the apparatus between the inductors 32 and 34 and remains there until removed at a later time not shown.
When a coin is interposed between the inductors 32 and 34, the amplitude of one or both of the frequency components o~ the signal induced in the coil of inductor 34 may be reduced depending on the material of the coin. The following table illustrates the effect of various materials on the amplitude of the low and high frequency components of the induced signal:
Materlal Effect on 50 Hz Effect on 70 KHz Signal Slgnal Paper, Plastlc No E~fect No ~fEect Copper Slight ~amping Slgnlficant Damping Copper-Nlckel No Effect Significant Damping Iron, Steel Significant Damping Heavy Damping Many of the world's genuine coins are made of conductive, nonferromagnetic materials (e.g. copper or cupro-nickel).
The presence of a coin of such material is indicated by significant damping of the 70 KHz signal coupled with only slight damping of the 50 Hz signal. Accordingly, the arrival sensor 30 is designed to recognise this condition and produce an output signal which is applied to the start gate solenoid 42 and the coin identifying circuit 44, when and only when this condition occurs. Non-conductive ob~ects (e~g. paper or plastic) are not '` detected by arrival sensor 30 and must be removed from the coin mechanism before it can be used, for example by operation oE
a coin reJect lever (not shown~ which momenLarily separates the front and back plates 14 and 16 and permits the ob~ect to fall from the mechanlsm in the usual manner. Magnetic coins are "recognised by heavy damping of both the 50 Hz and 70 KHz _9_ ~313055 signals". In ~he embodiment shown specifically in Figure 3 this condition resul~s in no output sign~l ~rom arrival sensor 30 and necessltates operation of the coin reject lever to remove the coin Erom the coin mechanism. Alternatively, the system can 6e arranged to produce an output signal for activating the start gate solenoid (but not the coin identlfying circuit 44) when heavy damping of both the low and high frequency signals is detected, thereby avoiding the necessity of operating the re~ect lever to purge the mechanism of a magnetic coin~ In applLcations in which magnetic coins may be acceptable coins, the system can be arranged to produce an output sl~n~ll Eor activating ~he st~rt gate solenold 42 and the coin :ldentlEyLn~
circuit 44 when heavy damplng of both the low and hlgh frequency signals is detected. Furthermore, if both magnetic and non-magnetic coins may be acceptable, the system may be modified to produce output signals indicative of whether the detected coin is magnetic or non-~agnetic. These signals may be applied to the coin identifying circuit 44 to pre-condition that circuit to accept only a coin having other characteristics consistent with the magnetic or non-magnetic characteristics of the coin.
These uariations can be made in any of the specific embodiments shown in Figures 3, 5 and 7.
Returning to the embodiment shown in Figure 3, the output signals of the low pass ilter 60 is applied to one input termlnal of a different~al amplLEier 66. The sig~al applied to the other input terminal of the amplifier 66 is a direct current (d.c.) threshold signal represented by the straight line sign~l trace (-V) ln Figure 4a. ~11 signal polarities referred to herein are entirely arbitrary. This threshold signal is generated by a rectifier circuit 62 and a voltage divider 64. The rectifier circuit 62 produces an output signal having a d.c. level proportional ~03~Q55 to the negative a~plitude of the output signal of the low . . , ~ ,, frequency power supply 36, i.e., a ~egative envelope slgnal.
The level of the signal -V derived from this negative envelope signal is ad~usted by voltage divider 64 to the desired negative threshold level -V applied to differential amplifier 66. The negatlve threshold level -V is chosen to be somewhat more positive than the negative peaks of the output signal of low pass filter 60 except when the output signal of the low pass filter 60 is damped to the degree associated with the presence of a ~agnetic coin between the inductors 32 and 34 as in the portion of Figures 4a to 4g.to the r~ght of line C-C. In other words, the negative peaks o~ the output single of low pass Ellter 60 will be more ne~ative than -V when n conductlve, non-magnetic coin Ls pre~nt between the inductor~ 32 and 3~, b~t will become more posit1ve than -V when a magnetic coin is present between the inductors 32 and 34. The differential amplifier 66 compares the levels of the signals applied to it and produces an output signal (represented by the signal trace of Figure 4b) which is positive when the output signal of low pass filter 60 is more negative than -V and negative otherwise.
The output signal of the differential ampli~ier 66 is applied to a rectifier circuit 68 which produces an output signal (represented by the signal trace of Figure 4e) which is the positive envelope of the applied signal. ~ccordingly, the output signal of the rectifier circuit 68 i9 positive while the output signal of the di~Eerential ampli~i~r 66 includes per~odic positive spi~es ~as in the portion of Fi~ure 4b to the left of line C-C?.
When those positive spikes disappear, however, the level of the output sIgnal o~ recti~ier circuit 68 goes rapidly to æero ti.e., within a time period tll) as in the portion of Figure 4e to the rig~t of line C-C. This latter condition i8 associated with ~38~i5 the arrival of a magnetic coin between the inductors 32 and 34.
, . ~
The output signal of the rectifier circuit 68 is applied to one input terminal of a NAND gate 8Q. When the output signal of rectifier circuit 68 is positive, it is interpreted by the NAND
gate 80 as logic 1, otherwlse it is interpreted as logic 0. Logic signal levels referred to herein are also entireIy arbitrary.
The circuitry associated with the high pass ilter 70 is similar to that described above. Thus a rectifier circuit 72 and a voltage divider 74 (~responsive to the output signal o~ the high ~requency power supply 38~ produce a positive threshold voltage +V (represented by the straight line signal trace of Figure 4c) which is applied to one input termlnal of a di~ferential ampliEler 76. (-~V 18 not necessarlly of the same magnltude a~ -V). ThLs poAltlve threshold voltage 18 cho~en ~o thut It Lc ~e~s positlve than the posltive peaks oE the output signal oE the high pass Eilter 70 except when there is a conductive ob~ect between lnductors 32 and 34. The output signal of the high pass filter 70 is applied to the other input termlnal of the dif~erential amplifier 76. Accordingly, the differential amplifier 76 (generally similar to the differential amplifier 66) produces an output signal (represented by the signal trace of Figure 4d) which is positive when the output signal level of the high pass filter 70 is less positive than +V and negative otherwise.
The output signal of the differential amplifier 76 is applied to a rectifier circuit 78 which produces an output signal (Figure 4f) proportional to the negative envelope oE the applied signal. Accordingly, the output signal o recti~ier circuit 78 is negative while the output signal of the differential amplifier 76 includes periodic negative ~pikes (as in the portions o~ Figure 4d to the left of line A-A and between lines B-B and C~C~. When the~e negative spikes disappear (as in the portions of Figure 4d . ,..._ ..
~038~5~;
between lines A-~ and B-B and to the right of line C-C~, the level of the output signal of the rectifier clrcuit 7~ goes rapidly to zero (i.e. after a time tl2~. For reasons explained below, tl2 is preferably greater than tll.
The output signal of the rectifier circuit 78 is applied to the remainlng lnput term:lnal o the NAND gate 80. When the output slgnal of the rectiier circuit 78 is zero it is interpreted by NAND gate 80 as logic 1, otherwise it is interpreted as logic O.
When both signals applied to the ~ND gate 80 are logic 1 (as in the portlon of Figllres 4a to 48 between lines ~-~ and B-B and after ti~le tl2), the N~ND gate 80 produces ~n outpu~ sLgn~l (see Flgure 4~) applied to a tlme dclay unlt 32 ~or actlvatlng the start gate solenoid 42 and the coln ldentlfylng circult 44.
Thls corresponds to the arrival of a conductive, non-magnetic coin between the inductors 32, 34. After a time delay tl3 imposed by the tlme delay unit 82 (i.e. at time B-B in Figures 4a to 4g), the "gate open" command signal produced by the NAND
gate 80 is applied to the start gate solenoid 42 and the coin is allowed to continue rolling down track 20 past the coin sensors 50. After time B-B in Figures 4a to 4g, the coin i9 no longer between the inductors 32 and 34 and the coin arrival sensor of Figure 3 returns to its original condition. The time delay tl3 ensures that all coins come to rest against the coin start gate 22 before being allowed to continue down the coin track 20.
As mentioned above, the portion of Figures 4a to 4g to the right of line C-C represents the response ~f the apparatus o~ Figure 3 to the arrlval o a magnetic coin between the inductors 32 and 34. The output signal amplitudes of both oE filters 60 and 70 drop below their respective re~erence signal levels (Figures 4a and 4c~. T~e OlltpUt signal level of the rectifier circuit 68 changes from logic 1 to logic 0 (Figure 4e) and the output signal le~el of the rectifler circ~it 78 changes from logic 0 to logic 1 (Figure 4f2. Since the response time tl2 of the rectifier circuit 78 is greater than the response time tll of the rectifier circuit 68, at no time following the arrival o the magnetic coin are the output signal levels of both rectifier circuits 68 and 78 logic 1. Accordingly, no "gate cpen" command signal is produced by the NAND gate 80 and the coin start gate 22 remains closed. As mentioned above, the magnetic coin is removed from the coin mechanism by operation of the coin re~ect lever (not shown).
In the alternative embod-lment of the invention shown in Figure 5, elements havlng the same reEerence number as elcments in Flgure 3 apart from the prefi~ number l are generally similar.
In the embodiment of Figure 5 the reference signals applied to differential amplifiers 166 and 176 are generated from the filtered receiver signals rather than the transmitter signals as in the embodiment shown in Figure 3. Accordingly, the leads 37 and 39 (shown in broken lines in Figure 2) are not needed and can be omitted when the receiver circuit 40 is constructed as shown in Figure 5.
In the embodiSment shown in Figure 5, the output signal of the receiving inductor 34 is amplified by an amplifier 158 to produce a received signal having a more convenient level.
This amplified signal is filtered by low and high pass filters 160 and 170 to produce output signals similar to the output signals of the Pilters 60 and 70 in the embodiment shown in Figure 3, albeit of somewhat greater amplitude as a result of amplification by the ampliPier 158. These signals are represented by the sinusoidal signal traces in Figures 6a and 6c respectlvely.
The several portions of Figure 6 represent the same events ~L~138~5 - represented by the corresponding portions of Figure 4, that is, ., , the port~on of ~igure 6 between lines A-A and B-~ represents the arrival of a condnctive, non-magnetic coin, the portion to the right of line C-C represents the arrival of a magnetic cain, and the remaining portiona represents the absence of any detecta61e ob~ect.
As in the embodiment shown in Figure 3, the output signals of the filters 160 and 170 in the embodiment of Figure 5 are respectively applied directly to one input terminal of differential amplifiers 166 and 176. The output signals of the filters 160 ~nd 170 are also respectively appl:Led to rectLfier circults 162 and 172. These rectlfler clrcuLts per~orm n Eunctlon simllar to the rectlfier clrcults 62 and 72 Ln the appnratu~
of Figure 3, that i9, the~ develop output signals whlch are proportional to the amplitude or envelope of the applied signal.
These signals are represented by signal traces -V and +V in Figures 6a and 6c. As can be seen in Figures 6a and 6c, the output signals of each of the rectifier circuits 162 and 172 is normally about 10% below the level (i.e. amplitude) of the output signal of the associated fil~er. However, when the output signal level of either filter drops as a result of the arrival of a conductive object between inductors 32 and 34, it takes a short time for the output signal of the associated rectifier to adjust to a level 10% below the new filter output signal level. If the new filter oubput signal level is below the former level of the output associated rectifier circuit output signal, the rectifier output signal level will be greater than the ~ilter output signal level for an interval o~ time t24 or t25, respectively. This causes the per$odic spikes in the output signal of the associated differential amplifier 166, 176 to cease temporarily (see Figures 6b and 6d). As in the embodiment shown in Figure 3, this causes ~11380S~
the output signal of the~asso¢iated rectifier circuit 168, 178 to change level after a time interv,al t21 or t22 (see Figures 6e and 6f~.
The e~nainder of the circuit shown in Figure 5 is substantially identical to the corresponding portion of Pigure 3.
~hus if the output signal of the rectifier circuit 178 changes to the loglc 1 state and the output signal of the rectifier circuit 168 remains in the logic 1 state, the NAND gate 180 produces an oubput signal which (after a delay t23 imposed by delay unit 182) activates the start gate solenoid 42 and the coin ldentifying circuit 44 (see Figure 6~ between lines A-A
and B-B). As in the embodiment shown in Figure 3, ~he rectlfier clrcult 168 responda more rapidly than the rect:Leler circult 178 (l.e. t22 18 ~reater tllan t21) 80 that LE both ~i~nals chan~e level (as ln the portlon of Flgures 6a to 6g to the right of line C-C) indicating the arrival of a magnetic coin, the output signal level of rectifier circuit 168 changes level to logic 0 first, thereby blocklng the NAND gate 180 and preventing a "gate open" command slgnal when the output signal of rectifier circuit 178 changes level to logic 1.
In the third embodiment shown in Figure 7, elements having the same reference number, apart from the prefix, as elements in Figure 3 or 5 are generally similar. In Figure 7 each of two differential amplifiers 266 and 276 basically compares two rectified versions of the output of filters 260 and 270.
Reference signals are generated by devices 262, 264 and 272, 274 and applied to one input terminal of the amplifiers 266 and 276. Accordingly, leads 37 and 39 shown in broken lines in Figure 2 are not needed and can be omltted when recelver circuit 40 is constructed as shown in Figure 7. Rectifier circuits 262 30 and 272 are characterised by response time constants t34 and ~L031~1~S~
t35, respectively. Rectifier circuit 263 (generally similar to rectif~er circuit 262 but with a shorter response time canstant t31~ produces a second rectiied version of the output signal o~ low pass filter 260 which is applied to the remaining input terminal of amplifier 266. The two signals applied to the amplifler 266 are represented by the signal traces shown in ~Lgure 8a. ~galn, the portion oE Figures 8a to 8d between lines A-~ and B-B represents the presence of a conductive, non-~agnetic coin, the portion of Figures 8a to 8d to the right of Line C-C represents the presence of a magnetic coin, and the remalning portion~ of Figures 8a to 8d represent the absence o~ any detectable obJect. The reference slgnal app:lled to the amp.tiEier 266 (the dotted slgnal trace ln Flgure 8a) 1~
normaLly ad~usted to a level ~llghtLy beLow the level of the output slgnal of the rectlfler 263 by the voltage divider 264.
This conditlon ls illustrated to the left of line C-C in Figure 8a. The slight damping of the output signal of the low pass filter 260 when a conductive, non-magnetic coin is interposed between the inductors 32 and 34 is not sufficient to cause the output signal of the rectifier 263 to fall below the reference signal level. As long as the output signal of the rectifier 263 is below the reference signal level, the output signal of amplifier 266 (shown in Figure 8b) remains strongly negative. This negative signal is blocked by a diode 267.
Significant damping of the output signal of low pass filter 260 (as the result, for example, of the appearnnce of a magnet:Lc coin between the inductors 32 and 34~ causes both signals applied to the amplifier 266 to drop (as in the portion of Figure 8a to the rlght oE L~ne ~-C). However~ because t34 is greater than t31, the output signal of the rectifier 263 drops more rapidly, causing it to momentarily fall below the reference 380S~
signal lèvel. This causes the output signal of the amplifier . ., 266 to change tv a positiYe polarIty as shown in Figure 8b, applying a strongly positive signal to one input terminal of a signal adder 269.
In the high :Erequency section o~ the apparatus shown in Figure 7, a rectifier circu:Lt 273 (simllar to the rectifier .272 but with a shorter response time constant t32) produces a second recti~ied version of the output signal of the high pass filter 270 which is added to the output signal of the low frequency section by the signal adder 269. An amplifier 276 compares the output signal of the adder 269 to the reEerence signal generated by the devices 272, 274 as described nbove.
(The two signals applled to ampllEler 276 are represented by the signal traces shown in Figure 8c, the dotted signal trace represents the reference signal). As long as the output signal of the amplifier 266 is nega~ive, that signal has no effect on the output signal of the rectifier 273. The amplifier 276 therefore compares directly the output signal of rectifier 273 with the reference signal level produced by the devices 272, 274. sy virtue of the voltage divider 274, this reference signal level is normally slightly below the output signal level of the rectifier 273 (as in the portion o~ Figure 8c to the left of line A-A). When a conductive, non-magnetic coin is introduced into the coin mechanism, both signals applied to the amplifier 276 drop. However, because t35 is greater than t32, the output signal of rectlfier 273 drops more rapidly, causing that signal to momentaril~ fall below the reference signal level (see the portion of Figure 8c between lines ~-A and B-B). Since th~er`e is no change in the output signal of the low frequency section, this re.versal of signal levels in the high frequency section is detected by the amplifier 276. The output signal of the ~38~S5 amplifier 276 (shown in Figure 8d2 therefore changes from negative to positive. This positive pulse is applied to a delay unit 282 as a "gate open" command signal. After a suitable delay, t33, this signal is used to activate the start gate solenoid 42 and coin recognition circuit 44.
I~ a magnetic coin i9 introduced into the coin mechanism, similar events occur in the high frequency section oP the apparatus. However, the strongly positive output signal of the low frequency section applied to the signal adder 269 keeps the signal applied to the associated input terminal o the amplifier 276 above the reference slgnal level applied to the other input terminal o~ the ampll1er 276 (see the portion o~ Flgure 8c to ~he right oE Line C-C). Thi0 kecp~ th~ o~ltpUt signal of the ampliEier 276 negatlve and prevents the apparatus from producing a "gate open" command signal. For thls purpose, the response tlme of the low frequency section of the apparatus is preferably less than that of the high frequency section.
Even after the disappearance of the positive signal from the low frequency section, the level of signal applied to the positive terminal of the amplifier 276 remains above the 2~ corre~ponding reference signal level and no "gate open" command signal is produced. The magnetic coin is removed from the coin mechanism by operation of the coin reject lever mentioned above.
It will be understood that the embodiments described herein are illustratlve oE the invention only and that various modifications can be made by those skilled in the art without departing Prom the scope of the invention. For example, although low and high frequencies of 50 to 60 Hz and 70 KHz, respectively, have been mentioned, it will be understood that any frequencies selected in accordance with the critèria set ~3~(~5iS
- forth above can be used instead of tho~e frequencies. With the low frequency 'referen'ce signal level set approximately 20% below the receiv~d signal amplitude in t~e absence of any detectable ob~ect, all highly conducti~e metals are effectively transparent (i.e. do not cause the received signal amplitude to fall below the reference signal amplitude) for low frequencie3 in the range from about 25Hz to about 125 Hz. The very small Dutch nickel ten-cent coin (,Dfl.,),10? causes ¢lightly less than threshold damping of the low frequency signal throughout this frequency range and is therefore identified as an acceptable coin. A
2.6 mm. thick copper disc is also identified a~ acceptable.
; With the high frequency reference signal set approximately 20 below the recelved slgnal amp~ltude ln the flbsence of any detectable obJect, the hlgh requency ~ec~lon may be operated at frequencies above about 40 KHz. At ~his and higher frequencies a cupro-nickel Swiss half franc causes slightly more t'han threshold damping of the high frequency signal and is identified as acceptable. Different threshold limits and coin detection requirements may, of course, allow other low and high frequencies to be used.
- ' .
each of the amplitudes of the components detected by the receiving means with the corresponding amplitude for coins of an acceptable type of material and for producing an output signal inclicative o the arrival o a coin of an acceptable type of material when the detected amplitudes of each of the components corresponds substantially to the corresponding amplitudes for a coin of an acceptable type of material.
Embodiments of the invention will now be described, by ~ - 5 -~1~3~ i5 way of example, with reference to the accompanying drawings, in which:-Figure 1 is a front view of a portion of a coin handlingmechanism showing one possible location for the inductors of a coin arrival sensor according to the present invention;
Figure 2 is a sectional view taken along the line 2-2 in Figure 1 with a schematic block diagram of the coin arrival sensor;
Figure 3 is a detailed block diagram of one embodiment of circuitry for the arrival sensor of Figures 1 and 2;
Figures 4a to 4g are a series of signal traces, plotted against a common timo axis, useful i.n understanding the embodiment of Pigure 3;
Figure 5 is a dotailed block dia~raal o:~ a secon(l ombodimont of circuitry for the arrival sensor oE Figures 1 and 2;
Figures 6a to 6g are a series of signal traces, plotted against a common time axis, useful in understanding the embodiment of Figure 5;
,, ~
~38~5~i Figure 7 i8 a detalled block diagram o~ a third embodi~ent o~ circuitry for the arrival sensor of Figures l and 2;
Pigures 8a to 8d are a series of 8ignal traces, plotted agains~ a common time axis, u~eful in understanding the embodiment o~ F:Lgure 7.
Throughout this speci1cation and in the appended claims, the ~erm "coin" i8 intended to mean genuine coins, tokens, counterfeit coins, slugs, washers, and any other item which may be used by persons in an attempt to use coin-operated devices.
In the coin handling device lO shown in Figures 1 and 2, a coin enters the device throu~h a coin entry 12 and falls edge first onto the initial portion oE a coin track 20 between parnllel Eront and back plates 14 nnd 16. The coln rol.l~ down thls portion of the coin track 20, coming to rest in the position shown by dotted line 24 against a coin start gate 22. In this position the coin is between transmitting and receiving inductors 32 and 34 of a coin arrival sensor 30 according to the present invention. The inductors 32 and 34 are mounted opposite one another on the plates 14 and 16, respectively. The inductors 32 and 34 are of such siæe and locatlon that when any coin acceptable to the device 10 is at rest against the coin start gate 22, substantially all of the electromagnetic energy ;
propagating from the i.nductor 32 to the inductor 34 passes through the coin.
When the arrival sensor 30 which include~ low and high ~requency power supplies 36 and 38 and a receiving circuit 40, detects a coin o an acceptable type of material between the inductors 32 and 34 as described in detail below, it produces an output signal applied to activate the start gate solenoid 42 and a coin identiEying circuit 44. In response, the start ~038(~S
gate solenoid retracts the start gate 22 into the back plate 16, allowing the coin to continue to roll down the coin track 20. When the coin identifying circuit 44 is activated, light sources associated with optical coin sensors 50 ~e.g. photoelectric devices~ are turned on. As the coin rolls down track 20 it passes the passage of the coln is sensed by the coin identifying circuit by means of the sensors 50. The coin identifying circu~t 44 determines whether or not the coin is acceptable, for example, by optically examining its velocity, diameter, etc., as disclosed in U.K. Patent Specificatian 1,272,560. ~t the end of coln track 20 the coin drop~ toward a coln acceptance gate 52. IE tha coln has been Ldentlfled as acceptable, the coln ac.~eptancc ~e 52 1B r~tracted lnto back plate l6 by a ~oLcno:ld (not ~hown) and the coin falls from the track 20 into a coln acceptance chute 54 leading to a coin box of the vending machine. If the coin is not recognised as acceptable, the coin acceptance gate 52 i9 not retracted and the coin falling from the end of the coin track 20 strikes the acceptance gate 52 and is diverted into a re~ect chute 56, which leads to a coin return window of the vending machine.
Figure 3 shows one form of the circuitry of the coin arrival sensor 30 of thiR invention including the low frequency power supply 36 and the high frequency power supply 38, aach of which is connected to a separate coil wound around the core of the transmitting lnductor 32. The low frequency power supply 36 produces an alternating current (a.c.) output signal having a first relatively low frequency (e.g. 50 or 60 Hz). The ultimate source of this signal may be mains. In that event, the power supply 36 may be a transformer for reducing the mains voltage to a safer level. The liigh frequency power supply 38 produces an a.c. output signal having a second relatively high ~333~ 5 ~requency (e.g. 70 KHz~. The power supply 38 may therefore be any suitable ~.c. signal generator, e.g. a square wave generator and a ~ilter for filtering the square wave to produce a sinusoidal signal.
As mentioned above, the a.c. output signal of each of the power supplies 36 and 3~ is applied to a separate coil on the core of the lnductor 32. Accordingly, the inductor 32 produces an alternating magnetic field which is the superposition of the alternating magnetic fields due to each of the applied a.c.
signals. This field radiates across the coin passageway above the coin track 20 in the apparatus of Flgures 1 and 2 and lnduces an a.c. electrlc~l slgnal ln the coll of the recelvLng :Lnductor 34. This lnduced slgnal ha~ frequ~ncy components correapondlng to the frequencles of the slgnals applled to the transmitting inductor 32. The output signal of the receiving inductor 34 is applled to low pass and high pass fllters 60 and 70 which separate the low and high frequency components of that signal.
The output signals of the low pass and high pass filters 60 and 70 are represented by the sinusoidal signal traces shown in Figures 4a and 4c, respectively. The p~rt~on of Figures 4a to 4g to the left of time line A-A represent the condition of the apparatus of Figure 3 priar to the arrival of a coin. For ease of illustration, the output signals of filters 60 and 70 are represented in Figures 4a and 4c as having frequencies much lower than is actually the case. Moreover, the output signal frequency of the filter 70 ls typically many tlmes greater than the output signal frequency of the ilter 60. At the time A-A, a conducti.ve, non-magnetic coin arrives in the apparatus between the inductors 32 and 34 and remalns there untll a time B-B when the coin start gate 22 is retracted. During the period indicated between lines B-B and C-C there is again no detectable object between the ~3805~
- inductors 32 and 34. At a ti~e C-C a magnetic coin arrives in the apparatus between the inductors 32 and 34 and remains there until removed at a later time not shown.
When a coin is interposed between the inductors 32 and 34, the amplitude of one or both of the frequency components o~ the signal induced in the coil of inductor 34 may be reduced depending on the material of the coin. The following table illustrates the effect of various materials on the amplitude of the low and high frequency components of the induced signal:
Materlal Effect on 50 Hz Effect on 70 KHz Signal Slgnal Paper, Plastlc No E~fect No ~fEect Copper Slight ~amping Slgnlficant Damping Copper-Nlckel No Effect Significant Damping Iron, Steel Significant Damping Heavy Damping Many of the world's genuine coins are made of conductive, nonferromagnetic materials (e.g. copper or cupro-nickel).
The presence of a coin of such material is indicated by significant damping of the 70 KHz signal coupled with only slight damping of the 50 Hz signal. Accordingly, the arrival sensor 30 is designed to recognise this condition and produce an output signal which is applied to the start gate solenoid 42 and the coin identifying circuit 44, when and only when this condition occurs. Non-conductive ob~ects (e~g. paper or plastic) are not '` detected by arrival sensor 30 and must be removed from the coin mechanism before it can be used, for example by operation oE
a coin reJect lever (not shown~ which momenLarily separates the front and back plates 14 and 16 and permits the ob~ect to fall from the mechanlsm in the usual manner. Magnetic coins are "recognised by heavy damping of both the 50 Hz and 70 KHz _9_ ~313055 signals". In ~he embodiment shown specifically in Figure 3 this condition resul~s in no output sign~l ~rom arrival sensor 30 and necessltates operation of the coin reject lever to remove the coin Erom the coin mechanism. Alternatively, the system can 6e arranged to produce an output signal for activating the start gate solenoid (but not the coin identlfying circuit 44) when heavy damping of both the low and high frequency signals is detected, thereby avoiding the necessity of operating the re~ect lever to purge the mechanism of a magnetic coin~ In applLcations in which magnetic coins may be acceptable coins, the system can be arranged to produce an output sl~n~ll Eor activating ~he st~rt gate solenold 42 and the coin :ldentlEyLn~
circuit 44 when heavy damplng of both the low and hlgh frequency signals is detected. Furthermore, if both magnetic and non-magnetic coins may be acceptable, the system may be modified to produce output signals indicative of whether the detected coin is magnetic or non-~agnetic. These signals may be applied to the coin identifying circuit 44 to pre-condition that circuit to accept only a coin having other characteristics consistent with the magnetic or non-magnetic characteristics of the coin.
These uariations can be made in any of the specific embodiments shown in Figures 3, 5 and 7.
Returning to the embodiment shown in Figure 3, the output signals of the low pass ilter 60 is applied to one input termlnal of a different~al amplLEier 66. The sig~al applied to the other input terminal of the amplifier 66 is a direct current (d.c.) threshold signal represented by the straight line sign~l trace (-V) ln Figure 4a. ~11 signal polarities referred to herein are entirely arbitrary. This threshold signal is generated by a rectifier circuit 62 and a voltage divider 64. The rectifier circuit 62 produces an output signal having a d.c. level proportional ~03~Q55 to the negative a~plitude of the output signal of the low . . , ~ ,, frequency power supply 36, i.e., a ~egative envelope slgnal.
The level of the signal -V derived from this negative envelope signal is ad~usted by voltage divider 64 to the desired negative threshold level -V applied to differential amplifier 66. The negatlve threshold level -V is chosen to be somewhat more positive than the negative peaks of the output signal of low pass filter 60 except when the output signal of the low pass filter 60 is damped to the degree associated with the presence of a ~agnetic coin between the inductors 32 and 34 as in the portion of Figures 4a to 4g.to the r~ght of line C-C. In other words, the negative peaks o~ the output single of low pass Ellter 60 will be more ne~ative than -V when n conductlve, non-magnetic coin Ls pre~nt between the inductor~ 32 and 3~, b~t will become more posit1ve than -V when a magnetic coin is present between the inductors 32 and 34. The differential amplifier 66 compares the levels of the signals applied to it and produces an output signal (represented by the signal trace of Figure 4b) which is positive when the output signal of low pass filter 60 is more negative than -V and negative otherwise.
The output signal of the differential ampli~ier 66 is applied to a rectifier circuit 68 which produces an output signal (represented by the signal trace of Figure 4e) which is the positive envelope of the applied signal. ~ccordingly, the output signal of the rectifier circuit 68 i9 positive while the output signal of the di~Eerential ampli~i~r 66 includes per~odic positive spi~es ~as in the portion of Fi~ure 4b to the left of line C-C?.
When those positive spikes disappear, however, the level of the output sIgnal o~ recti~ier circuit 68 goes rapidly to æero ti.e., within a time period tll) as in the portion of Figure 4e to the rig~t of line C-C. This latter condition i8 associated with ~38~i5 the arrival of a magnetic coin between the inductors 32 and 34.
, . ~
The output signal of the rectifier circuit 68 is applied to one input terminal of a NAND gate 8Q. When the output signal of rectifier circuit 68 is positive, it is interpreted by the NAND
gate 80 as logic 1, otherwlse it is interpreted as logic 0. Logic signal levels referred to herein are also entireIy arbitrary.
The circuitry associated with the high pass ilter 70 is similar to that described above. Thus a rectifier circuit 72 and a voltage divider 74 (~responsive to the output signal o~ the high ~requency power supply 38~ produce a positive threshold voltage +V (represented by the straight line signal trace of Figure 4c) which is applied to one input termlnal of a di~ferential ampliEler 76. (-~V 18 not necessarlly of the same magnltude a~ -V). ThLs poAltlve threshold voltage 18 cho~en ~o thut It Lc ~e~s positlve than the posltive peaks oE the output signal oE the high pass Eilter 70 except when there is a conductive ob~ect between lnductors 32 and 34. The output signal of the high pass filter 70 is applied to the other input termlnal of the dif~erential amplifier 76. Accordingly, the differential amplifier 76 (generally similar to the differential amplifier 66) produces an output signal (represented by the signal trace of Figure 4d) which is positive when the output signal level of the high pass filter 70 is less positive than +V and negative otherwise.
The output signal of the differential amplifier 76 is applied to a rectifier circuit 78 which produces an output signal (Figure 4f) proportional to the negative envelope oE the applied signal. Accordingly, the output signal o recti~ier circuit 78 is negative while the output signal of the differential amplifier 76 includes periodic negative ~pikes (as in the portions o~ Figure 4d to the left of line A-A and between lines B-B and C~C~. When the~e negative spikes disappear (as in the portions of Figure 4d . ,..._ ..
~038~5~;
between lines A-~ and B-B and to the right of line C-C~, the level of the output signal of the rectifier clrcuit 7~ goes rapidly to zero (i.e. after a time tl2~. For reasons explained below, tl2 is preferably greater than tll.
The output signal of the rectifier circuit 78 is applied to the remainlng lnput term:lnal o the NAND gate 80. When the output slgnal of the rectiier circuit 78 is zero it is interpreted by NAND gate 80 as logic 1, otherwise it is interpreted as logic O.
When both signals applied to the ~ND gate 80 are logic 1 (as in the portlon of Figllres 4a to 48 between lines ~-~ and B-B and after ti~le tl2), the N~ND gate 80 produces ~n outpu~ sLgn~l (see Flgure 4~) applied to a tlme dclay unlt 32 ~or actlvatlng the start gate solenoid 42 and the coln ldentlfylng circult 44.
Thls corresponds to the arrival of a conductive, non-magnetic coin between the inductors 32, 34. After a time delay tl3 imposed by the tlme delay unit 82 (i.e. at time B-B in Figures 4a to 4g), the "gate open" command signal produced by the NAND
gate 80 is applied to the start gate solenoid 42 and the coin is allowed to continue rolling down track 20 past the coin sensors 50. After time B-B in Figures 4a to 4g, the coin i9 no longer between the inductors 32 and 34 and the coin arrival sensor of Figure 3 returns to its original condition. The time delay tl3 ensures that all coins come to rest against the coin start gate 22 before being allowed to continue down the coin track 20.
As mentioned above, the portion of Figures 4a to 4g to the right of line C-C represents the response ~f the apparatus o~ Figure 3 to the arrlval o a magnetic coin between the inductors 32 and 34. The output signal amplitudes of both oE filters 60 and 70 drop below their respective re~erence signal levels (Figures 4a and 4c~. T~e OlltpUt signal level of the rectifier circuit 68 changes from logic 1 to logic 0 (Figure 4e) and the output signal le~el of the rectifler circ~it 78 changes from logic 0 to logic 1 (Figure 4f2. Since the response time tl2 of the rectifier circuit 78 is greater than the response time tll of the rectifier circuit 68, at no time following the arrival o the magnetic coin are the output signal levels of both rectifier circuits 68 and 78 logic 1. Accordingly, no "gate cpen" command signal is produced by the NAND gate 80 and the coin start gate 22 remains closed. As mentioned above, the magnetic coin is removed from the coin mechanism by operation of the coin re~ect lever (not shown).
In the alternative embod-lment of the invention shown in Figure 5, elements havlng the same reEerence number as elcments in Flgure 3 apart from the prefi~ number l are generally similar.
In the embodiment of Figure 5 the reference signals applied to differential amplifiers 166 and 176 are generated from the filtered receiver signals rather than the transmitter signals as in the embodiment shown in Figure 3. Accordingly, the leads 37 and 39 (shown in broken lines in Figure 2) are not needed and can be omitted when the receiver circuit 40 is constructed as shown in Figure 5.
In the embodiSment shown in Figure 5, the output signal of the receiving inductor 34 is amplified by an amplifier 158 to produce a received signal having a more convenient level.
This amplified signal is filtered by low and high pass filters 160 and 170 to produce output signals similar to the output signals of the Pilters 60 and 70 in the embodiment shown in Figure 3, albeit of somewhat greater amplitude as a result of amplification by the ampliPier 158. These signals are represented by the sinusoidal signal traces in Figures 6a and 6c respectlvely.
The several portions of Figure 6 represent the same events ~L~138~5 - represented by the corresponding portions of Figure 4, that is, ., , the port~on of ~igure 6 between lines A-A and B-~ represents the arrival of a condnctive, non-magnetic coin, the portion to the right of line C-C represents the arrival of a magnetic cain, and the remaining portiona represents the absence of any detecta61e ob~ect.
As in the embodiment shown in Figure 3, the output signals of the filters 160 and 170 in the embodiment of Figure 5 are respectively applied directly to one input terminal of differential amplifiers 166 and 176. The output signals of the filters 160 ~nd 170 are also respectively appl:Led to rectLfier circults 162 and 172. These rectlfler clrcuLts per~orm n Eunctlon simllar to the rectlfier clrcults 62 and 72 Ln the appnratu~
of Figure 3, that i9, the~ develop output signals whlch are proportional to the amplitude or envelope of the applied signal.
These signals are represented by signal traces -V and +V in Figures 6a and 6c. As can be seen in Figures 6a and 6c, the output signals of each of the rectifier circuits 162 and 172 is normally about 10% below the level (i.e. amplitude) of the output signal of the associated fil~er. However, when the output signal level of either filter drops as a result of the arrival of a conductive object between inductors 32 and 34, it takes a short time for the output signal of the associated rectifier to adjust to a level 10% below the new filter output signal level. If the new filter oubput signal level is below the former level of the output associated rectifier circuit output signal, the rectifier output signal level will be greater than the ~ilter output signal level for an interval o~ time t24 or t25, respectively. This causes the per$odic spikes in the output signal of the associated differential amplifier 166, 176 to cease temporarily (see Figures 6b and 6d). As in the embodiment shown in Figure 3, this causes ~11380S~
the output signal of the~asso¢iated rectifier circuit 168, 178 to change level after a time interv,al t21 or t22 (see Figures 6e and 6f~.
The e~nainder of the circuit shown in Figure 5 is substantially identical to the corresponding portion of Pigure 3.
~hus if the output signal of the rectifier circuit 178 changes to the loglc 1 state and the output signal of the rectifier circuit 168 remains in the logic 1 state, the NAND gate 180 produces an oubput signal which (after a delay t23 imposed by delay unit 182) activates the start gate solenoid 42 and the coin ldentifying circuit 44 (see Figure 6~ between lines A-A
and B-B). As in the embodiment shown in Figure 3, ~he rectlfier clrcult 168 responda more rapidly than the rect:Leler circult 178 (l.e. t22 18 ~reater tllan t21) 80 that LE both ~i~nals chan~e level (as ln the portlon of Flgures 6a to 6g to the right of line C-C) indicating the arrival of a magnetic coin, the output signal level of rectifier circuit 168 changes level to logic 0 first, thereby blocklng the NAND gate 180 and preventing a "gate open" command slgnal when the output signal of rectifier circuit 178 changes level to logic 1.
In the third embodiment shown in Figure 7, elements having the same reference number, apart from the prefix, as elements in Figure 3 or 5 are generally similar. In Figure 7 each of two differential amplifiers 266 and 276 basically compares two rectified versions of the output of filters 260 and 270.
Reference signals are generated by devices 262, 264 and 272, 274 and applied to one input terminal of the amplifiers 266 and 276. Accordingly, leads 37 and 39 shown in broken lines in Figure 2 are not needed and can be omltted when recelver circuit 40 is constructed as shown in Figure 7. Rectifier circuits 262 30 and 272 are characterised by response time constants t34 and ~L031~1~S~
t35, respectively. Rectifier circuit 263 (generally similar to rectif~er circuit 262 but with a shorter response time canstant t31~ produces a second rectiied version of the output signal o~ low pass filter 260 which is applied to the remaining input terminal of amplifier 266. The two signals applied to the amplifler 266 are represented by the signal traces shown in ~Lgure 8a. ~galn, the portion oE Figures 8a to 8d between lines A-~ and B-B represents the presence of a conductive, non-~agnetic coin, the portion of Figures 8a to 8d to the right of Line C-C represents the presence of a magnetic coin, and the remalning portion~ of Figures 8a to 8d represent the absence o~ any detectable obJect. The reference slgnal app:lled to the amp.tiEier 266 (the dotted slgnal trace ln Flgure 8a) 1~
normaLly ad~usted to a level ~llghtLy beLow the level of the output slgnal of the rectlfler 263 by the voltage divider 264.
This conditlon ls illustrated to the left of line C-C in Figure 8a. The slight damping of the output signal of the low pass filter 260 when a conductive, non-magnetic coin is interposed between the inductors 32 and 34 is not sufficient to cause the output signal of the rectifier 263 to fall below the reference signal level. As long as the output signal of the rectifier 263 is below the reference signal level, the output signal of amplifier 266 (shown in Figure 8b) remains strongly negative. This negative signal is blocked by a diode 267.
Significant damping of the output signal of low pass filter 260 (as the result, for example, of the appearnnce of a magnet:Lc coin between the inductors 32 and 34~ causes both signals applied to the amplifier 266 to drop (as in the portion of Figure 8a to the rlght oE L~ne ~-C). However~ because t34 is greater than t31, the output signal of the rectifier 263 drops more rapidly, causing it to momentarily fall below the reference 380S~
signal lèvel. This causes the output signal of the amplifier . ., 266 to change tv a positiYe polarIty as shown in Figure 8b, applying a strongly positive signal to one input terminal of a signal adder 269.
In the high :Erequency section o~ the apparatus shown in Figure 7, a rectifier circu:Lt 273 (simllar to the rectifier .272 but with a shorter response time constant t32) produces a second recti~ied version of the output signal of the high pass filter 270 which is added to the output signal of the low frequency section by the signal adder 269. An amplifier 276 compares the output signal of the adder 269 to the reEerence signal generated by the devices 272, 274 as described nbove.
(The two signals applled to ampllEler 276 are represented by the signal traces shown in Figure 8c, the dotted signal trace represents the reference signal). As long as the output signal of the amplifier 266 is nega~ive, that signal has no effect on the output signal of the rectifier 273. The amplifier 276 therefore compares directly the output signal of rectifier 273 with the reference signal level produced by the devices 272, 274. sy virtue of the voltage divider 274, this reference signal level is normally slightly below the output signal level of the rectifier 273 (as in the portion o~ Figure 8c to the left of line A-A). When a conductive, non-magnetic coin is introduced into the coin mechanism, both signals applied to the amplifier 276 drop. However, because t35 is greater than t32, the output signal of rectlfier 273 drops more rapidly, causing that signal to momentaril~ fall below the reference signal level (see the portion of Figure 8c between lines ~-A and B-B). Since th~er`e is no change in the output signal of the low frequency section, this re.versal of signal levels in the high frequency section is detected by the amplifier 276. The output signal of the ~38~S5 amplifier 276 (shown in Figure 8d2 therefore changes from negative to positive. This positive pulse is applied to a delay unit 282 as a "gate open" command signal. After a suitable delay, t33, this signal is used to activate the start gate solenoid 42 and coin recognition circuit 44.
I~ a magnetic coin i9 introduced into the coin mechanism, similar events occur in the high frequency section oP the apparatus. However, the strongly positive output signal of the low frequency section applied to the signal adder 269 keeps the signal applied to the associated input terminal o the amplifier 276 above the reference slgnal level applied to the other input terminal o~ the ampll1er 276 (see the portion o~ Flgure 8c to ~he right oE Line C-C). Thi0 kecp~ th~ o~ltpUt signal of the ampliEier 276 negatlve and prevents the apparatus from producing a "gate open" command signal. For thls purpose, the response tlme of the low frequency section of the apparatus is preferably less than that of the high frequency section.
Even after the disappearance of the positive signal from the low frequency section, the level of signal applied to the positive terminal of the amplifier 276 remains above the 2~ corre~ponding reference signal level and no "gate open" command signal is produced. The magnetic coin is removed from the coin mechanism by operation of the coin reject lever mentioned above.
It will be understood that the embodiments described herein are illustratlve oE the invention only and that various modifications can be made by those skilled in the art without departing Prom the scope of the invention. For example, although low and high frequencies of 50 to 60 Hz and 70 KHz, respectively, have been mentioned, it will be understood that any frequencies selected in accordance with the critèria set ~3~(~5iS
- forth above can be used instead of tho~e frequencies. With the low frequency 'referen'ce signal level set approximately 20% below the receiv~d signal amplitude in t~e absence of any detectable ob~ect, all highly conducti~e metals are effectively transparent (i.e. do not cause the received signal amplitude to fall below the reference signal amplitude) for low frequencie3 in the range from about 25Hz to about 125 Hz. The very small Dutch nickel ten-cent coin (,Dfl.,),10? causes ¢lightly less than threshold damping of the low frequency signal throughout this frequency range and is therefore identified as an acceptable coin. A
2.6 mm. thick copper disc is also identified a~ acceptable.
; With the high frequency reference signal set approximately 20 below the recelved slgnal amp~ltude ln the flbsence of any detectable obJect, the hlgh requency ~ec~lon may be operated at frequencies above about 40 KHz. At ~his and higher frequencies a cupro-nickel Swiss half franc causes slightly more t'han threshold damping of the high frequency signal and is identified as acceptable. Different threshold limits and coin detection requirements may, of course, allow other low and high frequencies to be used.
- ' .
Claims (34)
1. Apparatus for sensing the arrival of a coin in a coin handling mechanism and for producing an output signal when the coin is of an acceptable type of material comprising:
transmitting means including at least one transmitting inductor, for generating an oscillating magnetic field having components of two substantially different frequencies;
receiving means including at least one receiving inductor disposed in the magnetic field produced by said transmitting means for detecting the amplitude of said components at the location of said receiving inductor; means for guiding a coin between the transmitting and receiving inductors so that a substantial portion of the magnetic energy received by said receiving inductor is transmitted through the coin;
and separate means for comparing each of the amplitudes of the components detected by the receiving means with the corresponding amplitude for coins of an acceptable type of material and for producing an output signal indicative of the arrival of a coin of an acceptable type of material when the detected amplitudes of each of the components corresponds substantially to the corresponding amplitudes for a coin of an acceptable type of material.
transmitting means including at least one transmitting inductor, for generating an oscillating magnetic field having components of two substantially different frequencies;
receiving means including at least one receiving inductor disposed in the magnetic field produced by said transmitting means for detecting the amplitude of said components at the location of said receiving inductor; means for guiding a coin between the transmitting and receiving inductors so that a substantial portion of the magnetic energy received by said receiving inductor is transmitted through the coin;
and separate means for comparing each of the amplitudes of the components detected by the receiving means with the corresponding amplitude for coins of an acceptable type of material and for producing an output signal indicative of the arrival of a coin of an acceptable type of material when the detected amplitudes of each of the components corresponds substantially to the corresponding amplitudes for a coin of an acceptable type of material.
2. Apparatus according to claim 1 in which the transmitting means comprise an inductor core wound with two coils, the coils being connected to respective oscillator circuits oscillating at the said two different frequencies.
3. Apparatus according to claim, 1 or 2 in which the receiving means includes high and low pass filters connected to the inductor for isolating the higher and lower frequency components.
4. Apparatus according to claim 1 in which the comparing means include two comparators, a first comparator connected to the receiving means for comparing the detected amplitude of the high frequency component with the output of a first reference signal generator the first comparator producing an output signal if the said detected amplitude so deviates from the reference signal as to correspond to the signal for a conductive coin, and a second comparator connected to the receiving means for comparing the detected amplitude of the lower frequency component with the output of a second reference signal generator, the second comparator producing an output signal if the detected amplitude so deviates from the reference signal as to correspond to the signal for a ferromagnetic coin, and combinatorial means for providing the output signal for the comparing means only when the first comparator is producing its output signal and the second comparator is not producing its output signal.
5. Apparatus according to claim 4 in which the second comparator is adapted to respond more quickly to the presence of a ferromagnetic coin than the second coin responds to the presence of a conductive coin.
6. Apparatus according to claim 4 or 5 in which the said output signal of the first comparator corresponds to a logical value of 1 and the said output signal of the second comparator corresponds to a logical value 0, and the combinatorial means comprise a NAND gate, the NAND gate producing its output signal only if the signals from both comparators have a logical value 1.
7. Apparatus according to claim 4 or 5 in which the combinatorial means is adapted to combine the said output signal from the second comparator with the detected higher component to prevent it so deviating from the reference signal when a conductive ferromagnetic coin is present that the first comparator provides its output signal.
8. Apparatus according to claim 4 or 5 in which the reference signal generators are connected to the transmitting means to derive the reference signals from the currents that produce the high and low frequency magnetic fields.
9. Apparatus according to claim 4 or 5 in which the reference signal generators are connected to the receiving means to derive the reference signals from the high and low frequency components.
10. Apparatus according to claim 2 in which the receiving means includes high and low pass filters connected to the inductor for isolating the higher and lower frequency components.
11. Apparatus according to claim 10 in which the comparing means include two comparators, a first comparator connected to the receiving means for comparing the detected amplitude of the high frequency component with the output of a first reference signal generator, the first comparator producing an output signal if the said detected amplitude so deviates from the reference signal as to correspond to the signal for a conductive coin, and a second comparator connected to the receiving means for comparing the detected amplitude of the lower frequency component with the output of a second reference signal generator, the second comparator producing an output signal if the detected amplitude so deviates from the reference signal as to correspond to the signal for a ferromagnetic coin, and combinatorial means for providing the output signal for the comparing means only when the first comparator is producing its output signal and the second comparator is not producing its output signal.
12. Apparatus according to claim 11 in which the second comparator is adapted to respond more quickly to the presence of a ferromagnetic coin than the second coin responds to the presence of a conductive coin.
13. Apparatus according to claim 2 in which the comparing means include two comparators, a first comparator connected to the receiving means for comparing the detected amplitude of the high frequency component with the output of a first reference signal generator, the first comparator producing an output signal if the said detected amplitude so deviates from the reference signal as to correspond to the signal for a conductive coin, and a second comparator connected to the receiving means for comparing the detected amplitude of the lower frequency component with the output of a second reference signal generator, the second comparator producing an output signal if the detected amplitude so deviates from the reference signal as to correspond to the signal for a ferromagnetic coin, and combinatorial means for providing the output signal for the comparing means only when the first comparator is producing its output signal and the second comparator is not producing its output signal.
14. Apparatus according to claim 13 in which the second comparator is adapted to respond more quickly to the presence of a ferromagnetic coin than the second coin responds to the presence of a conductive coin.
15. Apparatus according to claim 5 in which the said output signal of the first comparator corresponds to a logical value of 1 and the said output signal of the second comparator corresponds to a logical value 0, and the combinatorial means comprise a NAND gate, the NAND gate producing its output signal only if the signals from both comparators have a logical value 1.
16. Apparatus according to claim 5 in which the combinatorial means is adapted to combine the said output signal from the second comparator with the detected higher component to prevent it so deviating from the reference signal when a conductive ferromagnetic coin is present that the first comparator provides its output signal.
17. Apparatus according to claim 11 in which the said output signal of the first comparator corresponds to a logical value of 1 and the said output signal of the second comparator corresponds to a logical value 0, and the combinatorial means comprise a NAND gate, the NAND gate producing its output signal only if the signals from both comparators have a logical value 1.
18. Apparatus according to claim 13 in which the said output signal of the first comparator corresponds to a logical value of 1 and the said output signal of the second comparator corresponds to a logical value 0, and the combinatorial means comprise a NAND gate, the NAND gate producing its output signal only if the signals from both comparators have a logical value 1.
19. Apparatus according to claim 11 in which the combinatorial means is adapted to combine the said output signal from the second comparator with the detected higher component to prevent it so deviating from the reference signal when a conductive ferromagnetic coin is present that the first comparator provides its output signal.
20. Apparatus according to claim 13 in which the combinatorial means is adapted to combine the said output signal from the second comparator with the detected higher component to prevent it so deviating from the reference signal when a conductive ferromagnetic coin is present that the first comparator provides its output signal.
21. Apparatus according to claim 5 in which the reference signal generators are connected to the transmitting means to derive the reference signals from the currents that produce the high and low frequency fields.
22. Apparatus according to claim 5 in which the reference signal generators are connected to the receiving means to derive the reference signals from the high and low frequency components.
23. Apparatus according to claim 6 in which the reference signal generators are connected to the transmitting means to derive the reference signals from the currents that produce the high and low frequency magnetic fields.
24. Apparatus according to claim 6 in which the reference signal generators are connected to the receiving means to derive the reference signals from the high and low frequency components.
25. Apparatus according to claim 7 in which the reference signal generators are connected to the transmitting means to derive the reference signals from the currents that produce the high and low frequency magnetic fields.
26. Apparatus according to claim 7 in which the reference signal generators are connected to the receiving means to derive the reference signals from the high and low frequency components.
27. Apparatus according to claim 17 in which the reference signal generators are connected to transmitting means to derive the reference signals from the currents that produce the high and low frequency magnetic fields.
28. Apparatus according to claim 18 in which the reference signal generators are connected to the receiving means to derive the reference signals from the high and low frequency components.
29. Apparatus according to claim 18 in which the reference signal generators are connected to the transmitting means to derive the reference signals from the currents that produce the high and low frequency magnetic fields.
30. Apparatus according to claim 18 in which the reference signal generators are connected to the receiving means to derive the reference signals from the high and low frequency components.
31. Apparatus according to claim 19 in which the reference signal generators are connected to the transmitting means to derive the reference signals from the currents that produce the high and low frequency magnetic fields.
32. Apparatus according to claim 19 in which the reference signal generators are connected to the receiving means to derive the reference signals from the high and low frequency components.
33. Apparatus according to claim 20 in which the reference signal generators are connected to the transmitting means to derive the reference signals from the currents that produce the high and low frequency magnetic fields.
34. Apparatus according to claim 20 in which the reference signal generators are connected to the receiving means to derive the reference signals from the high and low frequency components.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB54319/73A GB1483192A (en) | 1973-11-22 | 1973-11-22 | Arrival sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1038055A true CA1038055A (en) | 1978-09-05 |
Family
ID=10470622
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA214,346A Expired CA1038055A (en) | 1973-11-22 | 1974-11-21 | Coin arrival sensor using inductive colls |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US3918563A (en) |
| JP (1) | JPS5738945B2 (en) |
| CA (1) | CA1038055A (en) |
| DE (1) | DE2455112C2 (en) |
| FR (1) | FR2252612B1 (en) |
| GB (1) | GB1483192A (en) |
| HK (1) | HK183A (en) |
| ZA (1) | ZA747460B (en) |
Families Citing this family (32)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS51119292A (en) * | 1975-04-11 | 1976-10-19 | Nippon Signal Co Ltd:The | Screening of coin and its device |
| JPS5296598A (en) * | 1976-02-10 | 1977-08-13 | Nippon Koinko Kk | Coin examining means for automatic vending machines |
| US4106610A (en) * | 1976-06-07 | 1978-08-15 | Mars, Incorporated | Coin apparatus having multiple coin-diverting gates |
| US4385684A (en) * | 1979-07-17 | 1983-05-31 | Kabushiki Kaisha Nippon Coinco | Coin selection device |
| GR69124B (en) * | 1980-02-06 | 1982-05-03 | Mars Inc | |
| US4353452A (en) * | 1980-04-04 | 1982-10-12 | U.M.C. Industries, Inc. | Coin-handling device |
| GB2094008B (en) * | 1981-02-11 | 1985-02-13 | Mars Inc | Improvements in and relating to apparatus for checking the validity of coins |
| GB2093620B (en) * | 1981-02-11 | 1985-09-04 | Mars Inc | Checking coins |
| US4488116A (en) * | 1981-09-22 | 1984-12-11 | Mars, Incorporated | Inductive coin sensor for measuring more than one parameter of a moving coin |
| JPS58106453A (en) * | 1981-12-18 | 1983-06-24 | Sanee Denki Kk | Detector for metallic piece |
| GB8400046D0 (en) * | 1984-01-03 | 1984-02-08 | Starpoint Electrics Ltd | Coin checking |
| GB2170637A (en) * | 1983-04-12 | 1986-08-06 | Fki Electrical | Parking metres |
| GB2160689B (en) * | 1984-04-27 | 1987-10-07 | Piper Instr Limited | Coin detection |
| GB2168185B (en) * | 1984-12-05 | 1987-09-23 | Mars Inc | Checking coins |
| GB2173624B (en) * | 1985-04-08 | 1988-12-14 | Qonaar Corp | Low power coin discrimination apparatus |
| US4625852A (en) * | 1985-09-05 | 1986-12-02 | Coil Acceptors, Inc. | Coin detection and validation means and method |
| US4739869A (en) * | 1985-09-05 | 1988-04-26 | Coin Acceptors, Inc. | Coin detection and validation means and method |
| GB2207270B (en) * | 1987-07-20 | 1991-06-19 | Thomas Patrick Sorensen | Improvements in and relating to determining the characteristics of conducting objects |
| JP2567654B2 (en) * | 1988-03-31 | 1996-12-25 | 株式会社 日本コンラックス | Coin sorting method and device |
| US4936435A (en) * | 1988-10-11 | 1990-06-26 | Unidynamics Corporation | Coin validating apparatus and method |
| GB2235559A (en) * | 1989-08-21 | 1991-03-06 | Mars Inc | Coin testing apparatus |
| WO1993002431A1 (en) * | 1991-07-16 | 1993-02-04 | C.T. Coin A/S | Method and apparatus for testing and optionally sorting coins |
| US5293979A (en) * | 1991-12-10 | 1994-03-15 | Coin Acceptors, Inc. | Coin detection and validation means |
| DE4301530C1 (en) * | 1993-01-21 | 1994-06-30 | Nat Rejectors Gmbh | Inductive switch-on sensor for battery operated coin validators |
| US5526918A (en) * | 1995-06-15 | 1996-06-18 | Greenwald Industries Inc. | Coin validating apparatus and method |
| US5673781A (en) * | 1995-11-21 | 1997-10-07 | Coin Acceptors, Inc. | Coin detection device and associated method |
| GB2308004A (en) * | 1995-12-05 | 1997-06-11 | John Jervis Comfort | Coin recognition apparatus |
| DE59611050D1 (en) * | 1996-04-03 | 2004-09-09 | Ipm Internat S A | Device for checking the authenticity of coins, tokens or other flat metallic objects |
| US5799768A (en) * | 1996-07-17 | 1998-09-01 | Compunetics, Inc. | Coin identification apparatus |
| CA2262644A1 (en) | 1996-07-29 | 1998-02-05 | Qvex, Inc. | Coin validation apparatus |
| US6138813A (en) * | 1999-06-03 | 2000-10-31 | Mars, Incorporated | Coin mechanism with a piezoelectric film sensor |
| EP1383086A1 (en) * | 2002-07-19 | 2004-01-21 | Mars, Incorporated | Coin validation by signal processing |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1936898A1 (en) * | 1969-07-19 | 1971-02-04 | Pruemm Georg | Procedure for checking coins |
| GB1397083A (en) * | 1971-05-24 | 1975-06-11 | Mars Inc | Coin selector utilizing inductive sensors |
| US3870137A (en) * | 1972-02-23 | 1975-03-11 | Little Inc A | Method and apparatus for coin selection utilizing inductive sensors |
-
1973
- 1973-11-22 GB GB54319/73A patent/GB1483192A/en not_active Expired
-
1974
- 1974-11-21 CA CA214,346A patent/CA1038055A/en not_active Expired
- 1974-11-21 US US525840A patent/US3918563A/en not_active Expired - Lifetime
- 1974-11-21 FR FR7438249A patent/FR2252612B1/fr not_active Expired
- 1974-11-21 DE DE2455112A patent/DE2455112C2/en not_active Expired
- 1974-11-21 ZA ZA00747460A patent/ZA747460B/en unknown
- 1974-11-22 JP JP13374274A patent/JPS5738945B2/ja not_active Expired
-
1983
- 1983-01-06 HK HK1/83A patent/HK183A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| GB1483192A (en) | 1977-08-17 |
| ZA747460B (en) | 1975-11-26 |
| FR2252612B1 (en) | 1978-06-16 |
| JPS5087097A (en) | 1975-07-12 |
| JPS5738945B2 (en) | 1982-08-18 |
| DE2455112A1 (en) | 1975-05-28 |
| US3918563A (en) | 1975-11-11 |
| HK183A (en) | 1983-01-06 |
| FR2252612A1 (en) | 1975-06-20 |
| AU7560674A (en) | 1976-05-27 |
| DE2455112C2 (en) | 1986-11-27 |
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