A method of coin discrimination and a coin discriminator are disclosed which utilize a coin impeller, the impeller comprising magnetic field means for accelerating each coin to a velocity primarily dependent upon the coin's characteristics of electrical conductivity and density, for discriminating among coins based upon the trajectory of the accelerated coin.
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1. A method of determining the acceptability of coins comprising the steps of generating a traveling magnetic field, directing a coin to the magnetic field so that the force of the field impels the coin projecting it in a desired direction and accepting the coin only if it has a trajectory characteristic of a desired coin.
2. The method of claim 1 3 wherein desired coins are sorted in accordance with their characteristic trajectories.
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13. Apparatus for determining the acceptability of coins comprising traveling magnetic field producing means arranged to impel a coin and thereby project it into a trajectory, means for directing a coin to the magnetic field and means defining an acceptance window on the trajectory characteristic of a desired coin.
14. The apparatus of
15. The apparatus of
windows, each on a trajectory characteristic of a desired coin. 16. The apparatus of claim 14 for determining the acceptability of coins comprising a coin support track for supporting a coin on its edge, traveling magnetic field producing means arranged to impel a coin along the coin support track and thereby project it from the coin support track into a trajectory, means for directing a coin to the magnetic field and means defining an acceptance window on the trajectory characteristic of a desired coin, further comprising means for making a preliminary classification of the coin and producing a signal indicative of the classification and means responsive to the signal for selecting a value of a characteristic of the magnetic field. 17. The apparatus of claim 16 wherein the means for making the preliminary classification comprises a chordal dimension sensor. 18. The apparatus of claim 16 wherein the value selecting means comprises means for selection of the rate of change of the magnetic field. 19. The apparatus of claim 16 wherein the value selecting means comprises means for selecting the magnitude of the power supplied to the field producing means. 20. The apparatus of claim 17 wherein the value selecting means comprises means for selection of the rate of change of the magnetic field. 21. The apparatus of claim 17 wherein the value selecting means comprises means for selection of the magnitude of power supplied to the field producing means. 22. The apparatus of claim 16 wherein the value selection means are arranged to select a value of a characteristic of the magnetic field such that at least two varieties of desired coins are projected on trajectories passing through one or more acceptance windows at a single location. 23. The apparatus of claim 14 16 wherein the means for producing a traveling magnetic field is a linear impeller. 24. The apparatus of claim 23 further comprising a source of alternating current, start control means for connecting the current source to the linear impeller, and a zero-crossing detector connected to monitor the current source and connected to enable the start control means. 25. The apparatus of claim 14 for determining the acceptability of coins comprising a coin support track for supporting a coin on its edge, traveling magnetic field producing means arranged to impel a coin along the coin support track and thereby project it from the coin support track into a trajectory, means for directing a coin to the magnetic field and means defining an acceptance window on the trajectory characteristic of a desired coin, further comprising means for causing the magnetic field to travel in either of two opposed directions along the coin support track and a coin stop in the direction of travel opposed to the direction of projection. 26. The method of claim 25 further comprising at least one chordal dimension sensor adjacent the coin stop. . The apparatus of claim 14 16 in which the means defining an acceptance window comprises at least one movable barrier in the region into which coins are projected and means for moving the barrier responsive to an initial denomination determination. |
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This is a continuation-in-part of Pat. application, Ser. No. 120,652 now U.S. Pat. No. 3,701,405, filed Mar. 3, 1971, which is a continuation-in-part of application, Ser. No. 858,351, filed Sept. 16, 1969, now abandoned.
This invention relates to a method and apparatus which discriminate between coins according to their authenticity and denomination and, more particularly, relates to the use of a moving magnetic field to impel coins in a coin discriminator.
The coin discriminator of this invention accelerates coins of different denominations to a final velocity dependent upon the coin's characteristics, making it relatively simple to authenticate and sort coins accurately by spacial separation of different coins. Since the motion given to the coin through the coin discriminator system is effected primarily by the coin impeller, rather than by gravity, higher final velocities and more rapid sorting can be obtained. Reliability and effectiveness of the coin discriminator of this invention is high because of the minimal variation in velocity of coins of the same denomination, on the order of ± 2 percent. The coin impeller is capable of accelerating coins at several times the acceleration of gravity, thereby providing the potential for much more rapid coin sorting than is possible in devices which meansand the and the end wall 19. One or more of sensors 31, 32, and 33 is also used as a presence sensor to detect the arrival of a coin. The sensors examine the diameter of the coin and the logic circuitry determines which one of the preselected permissible coin denominations the coin is large enough to be.
A plurality of acceptance windows can be established, e.g.: by one of retractable pins or the like, on a plurality of trajectories; however, I will described in detail apparatus having one or more acceptance windows at a single location.
A pair of spaced pins are selected in response to that tentative determination from a group comprising either fixed pins 41 and 42 or the fixed mouth of a receptacle, and solenoid actuated retractable pins 43 and 44. The pins selected are arranged to establish an acceptance window of an appropriate dimension through which the trajectory of an acceptable coin passes. Unacceptable coins possess trajectories or diameters which cause such coins to hit the pins and bounce to be rejected. The spacing of acceptance window pins is arranged to provide just enough clearance to reliably accept authentic coins and reject unacceptable coins.
The appropriate acceptance window retractable pin 43 or 44 is selected, based on the preliminary denomination determination, and the impeller 16 is then electrically driven at level selected as a function of this initial determination. The levels of impeller drive are selected, e.g.: by selection of frequency or of current amplitude to choose the rate of change and strength of its magnetic field, to impart the velocity to the coin if it is authentic which will cause it to pass through the acceptance window for that initially determined denomination. If the coin is authentic and is of the denomination initially determined, it its trajectory path will clear the selected pair of pins of the group 41-44 and it will pass freely into a receiving bin 5 where it may actuate a sensor 50 to produce an output signal indicating the receipt of an acceptable coin. Thus, the initial denomination determination based on chodal chordal dimension is verified and the coin accepted.
To insure uniformity of final velocity, the impeller 16 can be driven in reverse briefly, impelling the coin against the end wall 19, before being driven in the forward coin accelerating direction. This initial impeller reversal tends to eliminate bounce or gravity induced initial velocity and insures that all coins start from zero velocity at the starting end of the track.
The operation of the apparatus shown in FIG. 2 is best described by reference to a three denomination set of coins such as the United States 5-cent, 10-cent and 25-cent coins. The sensors 31, 32, and 33, shown in FIG. 2, are located so as to be just obscured by 10-cent, 5-cent and 25-cent coins respectively. These three are the permissible denominations of this example. Sensor 31 is used as a coin presence sensor since any permissible coin will obscure it. Sensor 31 is connected to impeller start control 106 and the impeller drive level selector 60. Sensors 32 and 33 are connected to a logic circuit 25 whose outputs determine which if any of pins 43 and 44 are to be retracted and also are inputs to the impeller drive level selector 60.
If the coin obscures all three sensors 31-33, logic 25 initially determines that the coin is probably a 25-cent piece and retracts both pins 43 and 44 to provide a 25-cent piece sized acceptance window between fixed pins 41 and 42. Logic circuit 25 also provides a signal representative of a 25-cent piece to impeller drive level selector 60. Selector 60 yields a power output level for driving the impeller 16 at a level appropriate for a 25-cent piece. Assuming that the coin is an authentic 25-cent coin, and thus is potentially acceptable, the impeller will impart the proper velocity to the coin to cause it to pass freely between fixed pins 41 and 42 and to enter the bin 5 and activate sensor 50.
Referring now to FIG. 3 there is illustrated, for use in connection with the above described first and second embodiments, a stationary linear impeller means for producing a traveling magnetic field. A linear motor is similar to a stator of a conventional two phase cylindrical electric motor which has been slit along a radial plane and flattened. As is illustrated in FIG. 3, such an impeller 16 comprises two series of coils, a first series including coils 82 and 84 and a second series including coils 86 and 88. While only two coils per series are illustrated, a greater number of coils per series is preferred, particularly for the embodiment which is to be driven at various levels. The coils are wound around a low carbon steel impeller core 90 having projecting pole pieces or core fingers 92-95 spaced longitudinally along the desired direction of coin travel. A magnetic shunt or return path 98 is placed at the side of the coin track 12 opposite the impeller 16 to minimize the overall magnetic reluctance. The magnetic shunt may be made of a low carbon steel plate. It is desirable in the case of high flux densities that the core 90 be laminated steel.
In order to produce the effect of a traveling magnetic field, it is necessary for adjacent fields to have a phase shift relationship. FIG. 3 illustrates a circuit which is suitable for providing approximately a 90° phase shift between adjacent pole pieces 92-95. It can be seen that the first series of coils 82, 84 is wound in alternating fashion, in other words, coil 82 is wound in a counter-clockwise direction about pole 92 while coil 84 is wound clockwise about pole 94. The second series of coils 86, 88 similarly is wound in alternating fashion, namely coil 86 is wound counter-clockwise about pole 93 while coil 88 is wound clockwise about pole 95.
Either the first series or the second series of coils can be individually selectively connected directly to a source of cyclically varying current, for example, chopped D.C. or single phase sinusoidal A.C. current source 100, such as by AND gate 102 and AND gate 104 respectively, which are controlled by signals from start control circuit 106. In the case where single phase sinusoidal AC current is used, the two series are connected in parallel through a capacitor 108 thus placing the capacitor in series with the coil series not directly gated on. The capacitor 108 provides a 90° phase shift between the two series of coils. Because of the reversed direction of windings of adjacent coils within a series and the phase shift between the coil series provided by the capacitor 108, the magnetic field effectively travels in one direction. For example, at one instant of time assuming the polarity of the first coil 82 is north, the polarity of clil coil 86 is north plus 90° the polarity of coil 84 is south and the polarity of coil 88 is south plus 90°. The thrust direction of impeller 80 is reversed by merely enabling the presently disabled AND gate and vice versa. This permits reversal of thrust direction for the uniform coin starting condition purposes described above.
To provide consistent coin velocities, it is preferable to activate the impeller 16 each time at the same point in the supply current wave form. In this way the resultant coin velocity is not dependent upon the particular moment of time when the coin is first exposed to the magnetic field of the impeller. The zero crossing detector 109 is designed to detect the zero crossing of the impeller current in the direction providing desired initial polarity. The zero crossing detector 109 includes a saturation amplifier, a diode, a differentiator to select the desired direction of transition, and a latching relay operated by the output of the differentiator.
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| Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
| Dec 10 1973 | Mars, Inc. | (assignment on the face of the patent) | / |
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