Title:
SWITCHING ARRANGEMENT AND METHOD EMPLOYING COIN CONTROLLED MOTION TRANSDUCER
United States Patent 3559788


Abstract:
A switching effect is achieved by utilizing a transducer to convert motion of an inanimate object into an electrical signal. Transduction is achieved by having the moving object produce a cyclical flux change in a coil to generate an electrical pulse representative of the desired switching function.



Inventors:
Jensen, Herman G. (Chicago, IL)
Britton, Leon R. (Chicago, IL)
Application Number:
04/807823
Publication Date:
02/02/1971
Filing Date:
03/17/1969
Assignee:
SEEBURG CORP. OF DELAWARE:THE
Primary Class:
Other Classes:
307/108, 307/119, 310/15, 336/110
International Classes:
G07F5/10; G07F5/22; (IPC1-7): G07F1/00
Field of Search:
307/106,108,119 310
View Patent Images:
US Patent References:
2904707Impulse generatorSeptember 1959Drescher
2813988Mechanically activated source of electrical energyNovember 1957Griffin et al.
2617851Electric impulse generatorNovember 1952Bisch
2119811Resilient induction magnetJune 1938Green
1571693Coin-actuated signaling apparatusFebruary 1926DeVilliers



Primary Examiner:
Coleman, Samuel F.
Claims:
We claim

1. Apparatus to perform a switching function by producing an electrical signal pulse in response to the unidirectional motion of an inanimate physical body comprising a conductor;

2. Apparatus to perform a switching function by producing an electrical signal pulse in response to the unidirectional motion of an inanimate physical body comprising:

3. An apparatus as claimed in claim 2, wherein said induction means comprises an induction coil; and

4. An apparatus as claimed in claim 3, wherein said permanent magnet comprises a bar magnet; and

5. An apparatus to perform a switching function by producing an electrical signal pulse in response to the unidirectional motion of an inanimate physical body comprising a coil;

6. An apparatus as claimed in claim 5, wherein said filter circuit comprises a unidirectional conducting device connected in series with said coil.

7. An apparatus as claimed in claim 6, and further comprising:

8. An apparatus as claimed in claim 7, wherein:

9. Apparatus to perform a switching function by producing an electrical signal pulse in response to the unidirectional motion of an inanimate physical body comprising:

10. An apparatus as claimed in claim 9, wherein:

11. An apparatus to perform a switching function by producing an electrical signal pulse in response to the unidirectional motion of an inanimate physical body comprising:

12. An apparatus as claimed in claim 11, wherein:

13. Apparatus to perform a switching function in a vending machine by providing an electrical signal pulse in response to the unidirectional motion of an article deposited or displaced therein comprising an induction coil;

14. An apparatus as claimed in claim 13, wherein said magnetic means comprises a permanent magnet reciprocably moved in said coil by said converting means.

15. An apparatus as claimed in claim 14, wherein said permanent magnet is a bar magnet;

16. An apparatus as claimed in claim 13, wherein said magnetic means comprises a U-shaped permanent magnet; and

17. An apparatus as claimed in claim 16, wherein:

18. Apparatus to perform a coin switch function in a vending machine by converting the falling motion of a deposited coin into an electrical credit pulse comprising:

19. An apparatus claimed in claim 18, wherein said permanent magnet is a bar magnet driven in a reciprocable fashion by said lever means and said bias means; and said bias means is a spring attached to said bar magnet and disposed to oppose displacement of said lever means.

20. An apparatus as claimed in claim 19, wherein said filter circuit comprises a first diode, a variable capacitor connected in series with said induction coil and said first diode, and a second diode connected across said capacitor.

21. An apparatus as claimed in claim 18 wherein:

22. An apparatus as claimed in 21 wherein said filter circuit comprises a first diode, a variable capacitor connected in series with said induction coil and said first diode, and a second diode connected across said capacitor.

23. A method of producing a switching function in response to the falling motion of a coin deposited in a vending machine comprising:

Description:
BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a switching device based upon transduction of motion into an electrical signal, and more particularly, this invention is directed to a coin switch arrangement which utilizes reciprocation of a permanent magnet in a coil to convert the motion of a coin deposited in a vending machine into an electrical pulse to provide a credit signal.

2. Description of the Prior Art

In coin operated vending machines it is necessary to provide means to sense the deposit of coins therein and to relay this information to a credit registering arrangement. In prior art vending machines, electrical switches which provide an electrical signal in response to the passage of a coin have been employed for this purpose. A normally open switch having a pair of contact carrying blades is provided for each type of coin to be accepted by the vending machine. A pivoted lever is also provided for each type of coin to be accepted, and each such lever has a first end positioned in the path of coins of the type with which it is associated and a second end positioned to close the corresponding switch and generate a credit-indicating output pulse.

Various problems have been encountered in connection with the use of coin switches such as those described above. The contact carrying blades are normally maintained in a spaced relationship relative to one another and are adjusted to come together only upon application of a predetermined closing force. It is quite difficult to adjust the switches to require the proper closing force, since a tolerance of only one or two grams must be maintained. If the closing force is improperly determined, or fixed, "break-up" may occur in the electrical signal passed by the switch. That is, either or both of the switch blades may oscillate following the deposit of a single coin in such a manner that the contacts carried thereby may engage each other several times, and thereby send several output pulses to the credit registering apparatus to register a larger credit than that to which the operator is entitled. In addition, improper adjustment of the switch may prevent the coin from passing the first end of the pivoted lever after coming in contact therewith, thus causing the coin to "bounce" against the lever several times. Once again this may result in multiple output pulses or "break-up."

Moreover, the switch arrangements described above have permitted operators to "cheat" the vending machines in which they are utilized. By shaking or jarring the machines' cabinets, operators have initiated closure of the coin switches and obtained unwarranted registry of credit.

Further problems encountered in connection with the use of the coin switches of the prior art concern the contacts carried by the switch blades. In the operation of vending machines, deposits of dirt or corrosion frequently form on the contacts and prevent proper closure of the switch. Thus, the operator may be "cheated" by the machine when the coin he deposits does not register a credit due to the failure of the switch to close and relay an output signal pulse.

Furthermore, during the operation of the vending machine the contacts are subject to wear through frequent engagement and must be periodically replaced if the machine is to function properly.

In addition to the coin switch operations, vending machines utilize various other motion detecting switches (e.g., detecting the actual discharge of an article or receptacle). While the disadvantages of these switching arrangements may differ from the coin switch problems in some details, the basic problems of obtaining an accurate indication of the number of moving objects passing a specified point is the same.

SUMMARY OF THE INVENTION

In order to overcome the disadvantages which inhere in the electrical switches of the prior art, applicants have invented a transducer which utilizes the principles of electromagnetism to convert the motion of an article deposited or displaced in a vending machine into an electric signal pulse. By replacing the electrical coin switches with an electromagnetic transducer in accordance with the present invention, the problems of signal "break-up" and "cheating" are minimized. The prior art devices require a power source to generate an electric signal pulse each time an electrical circuit is closed, and a signal is produced at the output whether or not each closure is effected by the deposit of a separate coin.

In contrast thereto, in the transducer of applicants' invention the electrical signal pulse is generated by the motion of the coin itself, rather than by circuit closure, thus ensuring that unwarranted signals will not be relayed to the coin during counting device. Furthermore, since applicants' invention does not involve circuit closure, the problems involved in the degeneration and maintenance of the contacts of the prior art electrical coin switches do not appear in the electromagnetic transducer.

Two embodiments of applicants' invention are described in the instant application. Briefly, both embodiments involve the transformation of a unidirectional motion of an inanimate body into a cyclical variation of a magnetic field (which may also be defined in terms of a reluctance change in a magnetic circuit). This transformation is achieved by utilizing a converting means, such as a pivoted lever in combination with a biasing spring, to produce a reciprocable motion of an element affecting a magnetic circuit. While the pivoted lever arrangement provides a particularly useful converting means, there are other efficacious approaches (e.g., a ramp directly on the element or a direct driving of a vertically positioned element). The cyclical variation in the magnetic field produces flux changes in a conductor such as a helical coil, which also provides a self-induction effect. Of course, the conductor need not be a helical coil as, for example, one variation of the preferred embodiments might involve the motion of a straight conductor in a fixed magnetic field. Since the flux changes will generally induce at least two signals in the conductor, it is necessary to filter out undesired signals to produce a single electrical pulse as an output. While this filtering could be achieved by various types of control means (e.g., mechanical or electromechanichemical arrangements), the disclosed embodiments utilize an electrical filter circuit. The filtered pulse may then be used as a switch output.

With specific reference to the two embodiments disclosed herein, the first embodiment involves a permanent bar magnet mounted for reciprocable motion in a coil of wire. One end of a pivoted lever contacts an end of the bar magnet to drive the magnet as the lever is pivoted by a falling coin engaging the other end thereof. A biasing spring is attached to the bar magnet and disposed so as to oppose pivotal displacement of the lever and to return the lever to its initial position. The resulting reciprocable motion of the bar magnet induces electrical signals in the coil. As only a single pulse is desired for each coin that drops, a filter circuit is employed to prevent undesired signals from being passed. The filter circuit has a unidirectional conducting device (diode) in series with the coil and a storage element (capacitor). A limiting device (a second diode) is connected across the capacitor to limit the amplitude of the output pulse. The output pulse may then be used to initiate any desired function, such as the registry of a predetermined amount of credit.

In the second embodiment of applicants' invention, the movable permanent bar magnet of the first embodiment is replaced by a fixedly mounted U-shaped permanent magnet having an induction coil wound around one of its legs. A pivoted lever has an armature for closing the open end of the U-shaped magnet attached to one end thereof. A falling coin engages the other end of the lever to cause a displacement of the lever, and a biasing spring returns the lever to its initial position. The resulting reciprocable motion of the armature produces a cyclical variation in the reluctance of the magnetic circuit including the U-shaped magnet. The variation in reluctance produces a corresponding change in the flux linking the coil to induce electrical signals in the coil. The same filter circuit is utilized to eliminate undesired signals.

Although both embodiments of applicants' invention have been briefly described in the context of their transduction of the motion of coins deposited in vending machines into a control signal, it should be emphasized that their use is not limited to this function. In many situations where it is desired to convert motion into an electrical control signal the present invention can be employed to advantage. Moreover, applicants' invention can be employed in vending machines for purposes other than the registering of credit. For example the dropping of a cup in a beverage dispenser can be converted into a signal pulse to initiate the liquid dispensing operation.

The advantages of applicants' electromagnetic transducer over the electrical switches used in the prior vending machine art are evident. As mentioned above, the transducer does not require an independent power source to produce a control signal but is designed to convert coin motion into an electrical pulse through the induction of voltage in a coil. Also, the problems of "break-up" (multiple signals generated by a single coin deposit) and "cheating" are substantially eliminated, since the transducer does not involve the critical adjustment of circuit completion elements (switch blades). Applicants' invention will insure the production of a single pulse corresponding to a single coin deposit and will prevent a control signal from being generated through the jolting of the machine cabinet. Moreover, since the present invention does not require electrical contacts, the difficulties heretofore encountered with regard to deposits forming thereon and contact wear are eliminated.

Accordingly, it is a primary object of the present invention to provide a switching function by transducing the motion of a physical object into a single electrical control signal.

It is a further object of this invention to provide an electromagnetic motion transducer to replace an electrical coin switch in a vending machine.

It is a still further object of the present invention to provide an electromagnetic motion transducer to convert the motion of a coin deposited in a vending machine into an electrical signal pulse to register the establishment of credit in a coin counting device.

It is yet a further object of the present invention to replace electrical coin switches in vending machines with electromagnetic motion transducers and thereby minimize the possibilities of signal "break-up" and of "cheating" of the machine.

An additional object of this invention is to eliminate the necessity for finely adjusting the circuit closing means of electrical switches used in vending machines by replacing the switches with an electromagnetic motion transducer which can be simply and easily adjusted to provide a suitable signal pulse.

The foregoing and other objects, advantages, and features of the subject invention will hereinafter appear and for purposes of illustration, but not of limitation, two exemplary embodiments of the subject invention are shown in the appended drawing.

DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of a first embodiment of a coin switch arrangement made in accordance with the present invention.

FIG. 2 is a side view of the coin switch arrangement illustrated in FIG. 1.

FIG. 3 is a perspective view of a second embodiment of a coin switch arrangement made in accordance with the present invention.

FIG. 4 is a side view of the coin switch arrangement illustrated in FIG. 3.

FIG. 5 schematically illustrates a filter circuit utilized in the present invention.

FIG. 6 schematically illustrates electrical signals induced in the coil shown in FIG. 5.

FIG. 7 schematically illustrates the electrical pulse appearing across the capacitor shown in FIG. 5.

DESCRIPTION OF PREFERRED EMBODIMENTS

Two embodiments of an electromagnetic motion transducer made in accordance with the present invention are illustrated in the drawings. For present purposes, the two embodiments are described as they are utilized in a vending machine to convert coin motion into a single electrical signal pulse for relay to a credit register. However, it should be emphasized that their use is not limited to this function. In addition, only a single example of each of the embodiments of applicants' invention will be described, but it should be recognized that a plurality of transducers made in accordance with the present invention would ordinarily be employed in a vending machine, one for each denomination of coinage that the machine is designed to accept for credit.

Referring to FIG. 1, a case 10 comprises vertical members 12 and 14, and horizontal members 16 and 18. A vertically extending plate 20 is attached to horizontal member 16 and extends across the entire width of the interior of case 10 to support induction assemblies 22.

Case 10 is maintained within a body 24, but in practice it may also be separated therefrom in such a manner that the lever and coin chute arrangements, and the induction arrangement are separate assemblies. As shown in FIG. 1, body 24 comprises vertical side members 26 and 30, a vertical end member 32, and a horizontal bottom member 33. A horizontal pivot rod 34 is supported by side members 26 and 30 adjacent depending plate 20 and extends across the width of the case 10. Pivot 34 supports pivotable lever assemblies 36 within body 24. Additional vertical members 38, parallel to side members 26 and 30, are disposed within body 24 adjacent each lever assembly 36, and form chutes to control the path of vertical fall of a deposited coin. The space beneath bottom member 33 is open to allow deposited coins to fall therethrough after engaging a given one of the lever assemblies 36.

Referring to FIG. 2, an induction assembly 22 comprises an induction coil 42, maintained with its axis in a horizontal plane, and a permanent bar magnet 44 maintained in a horizontal plane with its longitudinal axis parallel to and essentially coincident with the axis of the coil. Coil 42 is fixedly attached to the side away from the bar magnet 44 of a depending vertical flange 46 attached to plate 20. A hole is provided in flange 46 in alignment with the interior of the coil 42 to permit the passage therethrough of the bar magnet 44, so that a portion of the length of the bar magnet may enter the interior of the coil.

Bar magnet 44 has a cam follower 48 attached to its end away from the coil 42, and bar magnet 44 is supported at this end by lever assembly 36 and at its end adjacent the coil by the vertical flange 46. The magnet is normally maintained in its biased rest position (shown in FIG. 2) by a compression spring 50 surrounding its length, abutting at one end upon the cam follower 48 and at its other end upon the vertical face of flange 46 away from the induction coil. In its normal biased position, the end of the magnet 44 adjacent the coil 42 is not disposed within the interior of the coil, but upon the application of a driving force opposite to the bias on the magnet, a portion of the magnet is driven through the hole provided in flange 46, into the interior of the coil 42 (shown in phantom lines; FIG. 2). Alternatively, the normal biased position of magnet 44 may be one in which a portion of the magnet is disposed within the coil, with the driving force causing a further portion of the magnet to enter the coil's interior. When this driving force is removed, the spring 50, which is compressed between cam follower 48 and flange 46 as the magnet enters the coil, returns the magnet to its normal rest position, removed from the interior of the coil.

The driving force is provided by lever assembly 36, which comprises a pivoted lever 52 that includes a first section 54 having an upper surface 56 adapted to be engaged by a coin 62 as it falls past the lever. Lever 52 also comprises a second section 58 having a cam member 60 attached at its end away from the first section 54. At the junction of first section 54 and second section 58, lever 52 is pivotably supported by pivot member 34. The second section 58 is normally maintained in a vertical plane and is positioned so that cam member 60 is held in contact with cam follower 48 on magnet 44 by the weight of section 54. The cam member 60 acts as a stop to prevent the magnet 44 from travelling, according to its bias, past its normal rest position (shown in FIG. 2). When coin 62 contacts the upper surface 56 of the first lever section 54, the lever 52 is caused to pivotably rotate and cam member 60, acting upon cam follower 48, drives the magnet 44 in the direction of the coil 42, thus causing a portion of the magnet's length to enter the interior of the coil. After striking surface 56 and causing lever 52 to rotate, the coin 62 continues its vertical fall through the space provided in horizontal member 33. When the coin passes the lever 52, spring 50 expands and withdraws magnet 44 from coil 42 and returns it to its normal position. On this return stroke of magnet 44, cam follower 48, acting upon cam member 60, causes lever 52 to pivotally rotate to its normal position wherein the second section 58 thereof is positioned vertically and acts as a stop to prevent further travel of magnet 44.

The mechanical arrangement described above converts the vertical fall of the coin 62 into electrical signals induced in coil 42 which may be relayed to a credit registering device. A filter circuit 68, schematically represented in FIG. 5, is connected to the induction coil 42. The driving of the magnet 44 into the interior of the coil 42 (caused by the coin 62 striking the lever 52) produces a change in the flux linking the coil and thereby induces a voltage in the coil. The induced voltage has a positive potential at end 64 of coil 42, with respect to ground potential at end 66 of the coil. A blocking diode 70 has its cathode connected to end 64 of coil 42 to prevent current flow in response to this induced voltage, and therefore no signal pulse is read across the output terminals represented at 72 and 74. The induced voltage pulse is represented by reference numeral 76 in FIG. 6. During the rapid return stroke of the magnet 44 to its normal rest position, after the coin 62 passes lever 52, the flux linking the coil 42 is again changed and a voltage of the opposite polarity (i.e., end 64 of coil 42 is negative with respect to grounded end 66) is induced in the coil. This voltage forward biases diode 70 and produces a current flow in the circuit. This current flow is through a storage capacitor 80 which rapidly charges to the potential of the induced voltage and therefore a signal pulse is obtained at output terminals 72 and 74 of the circuit. The length of this signal pulse may be adjusted by means of the variable capacitor 80 connected in series with coil 42 and diode 70. This adjustability feature is useful in regulating the length of the output pulse to ensure that the signal produced has the proper characteristics to register credit in the device to which it is relayed.

Capacitor 80 also serves to prevent the phenomenon of signal "break-up" frequently encountered in connection with the use of the electrical coin-switches of the prior art. If the vertical fall of the coin 62 does not occur in a normal fashion, and the coin does not pass the lever 52 after its first contact therewith, "coin-bounce" (subsequent contact of the same coin with the lever) may result. This "coin-bounce" may cause the magnet to oscillate slightly within the interior of the coil, thus inducing small voltage pulses therein. However, the capacitor 80, by increasing the length of the output pulse, prevents the induced voltage from producing separate output signals. That is, by lengthening the output pulse the capacitor will provide for the incorporation of the small pulses induced in the coil by "coin-bounce" into the single pulse obtained at the output.

The single output signal obtained at the output terminals 72 and 74 is represented by reference numeral 82 in FIG. 7. As mentioned above, the shape of this signal can be changed to some degree by adjusting the capacitance of the variable capacitor 80. The voltage pulses appearing across the coil 42 upon the withdrawal of magnet 42 therefrom are schematically indicated by reference numerals 84 and 86 in FIG. 6. As the magnet 44 is withdrawn from the coil 42, the change in flux linking the coil induces a current flow through diode 70 and capacitor 80 which charges the capacitor to yield output pulse 82. While the polarity of the induced voltage is such as to forward bias diode 70, the actual potential appearing across coil 42 is the counter e.m.f. 84 expressed as L di/dt. When the magnet 44 comes to rest in its normal position, there is no longer an induced voltage in coil 42 and the current rapidly decays to zero. This decaying current produces an L di/dt voltage pulse 86 across the coil opposite in polarity to pulse 84 produced by the increasing current upon initiation of the return stroke of magnet 44.

A comparison of FIGS. 6 and 7 illustrates the function of the filter circuit 68. This circuit prevents an output signal from being produced during insertion of magnet 44 into coil 42, and converts the return stroke of magnet 44 into the single output signal represented by reference numeral 82.

A limiting diode 84 is also included in the filter circuit 68 and is connected across capacitor 80. This limiting diode functions to limit the amplitude of the output signal in the following manner. The diode is normally reverse biased by the charge on the capacitor 80 to prevent flow of current from terminal 88 to terminal 90, and thus the voltage potential between these terminals is the same as that across the output terminals 72 and 74. When this potential reaches a certain level, however, the diode "breaks down," permitting current to flow from terminal 88 to 90, thus limiting the potential across the output to the "break-down" level. The diode 84, thus keeps the amplitude of the output signal from exceeding a certain level.

A second embodiment of applicants' invention is illustrated in FIGS. 3 and 4. The case 10 and body 24 are the same as in the first embodiment, and the elements comprising the case and body are indicated by primed reference numerals corresponding to those employed in FIG. 1.

Referring to FIG. 4, an induction assembly 90 comprises a U-shaped permanent magnet 92, having an upper arm 94 and lower arm 96 of equal length. The magnet 92 is fixedly maintained on a support plate 98 attached to a vertical member 100 of body 24. Induction assembly 90 also includes an induction coil 102 which surrounds lower arm 96 of the U-shaped magnet 92 and which is maintained in this position by attachment to the bight of the U.

A lever assembly 104 comprises a lever 106 including a first section 108 having an upper surface 110 positioned in the path of a coin 62 as it falls vertically through a chute in body 24. Lever 106 further comprises a second section 112 having an armature 114 attached to its end away from the first section 108. At the junction of the first section 108 and second section 112, the lever 106 is pivotally mounted on a pivot 34. The lever 106 is biased toward a rest position by a tension spring 116, one end of which is attached to first lever section 108 and the other end of which is fastened to support plate 98. In its biased rest position, lever 106 has its first section 108 in a horizontal plane and its second section 112 positioned adjacent the arms 94 and 96 of the U-shaped magnet so that the armature 114 is not touching either of the arms.

When coin 62 engages the upper surface 110 of first lever section 108, lever 106 is pivotally rotated about pivot 34, until armature 114 simultaneously contacts both arms 94 and 96 of the U-shaped magnet. As coin 62 passes the first lever section 108, the spring 116 returns the lever 106 to its normal rest position and the armature 114 is moved out of contact with the arms of the magnet.

The simultaneous contact of both arms of the U-shaped magnet by plate 114 (caused by the coin 62 striking the lever 106) decreases the reluctance of the magnetic circuit and causes a rush of flux flow through the U-shaped magnet, which produces a change in the flux linking coil 102 surrounding lower arm 96. The change in flux linking coil 102 induces a voltage therein analogous to the voltage induced in the coil 42 of the first embodiment of applicants' invention when the magnet 44 enters the coil 42. Similarly, as armature 114 moves out of contact with the arms of the U-shaped magnet (as the coin 62 passes the first lever section 108), a voltage is induced in coil 102 analogous to the voltage induced in coil 42 of the first embodiment when the magnet 44 employed therein is removed from the coil.

Attached to the coil 102 are leads 118 and 120 which connect the coil with a filter circuit identical to that employed in connection with the first embodiment, as described hereinbefore (illustrated in FIG. 5). As in the case of the first embodiment, this filtering circuit is adapted to convert the voltage pulses read across the coil (illustrated in FIG. 6) into a single output signal of variable length and controlled amplitude (illustrated in FIG. 7).

Those skilled in the art will recognize that the electromagnetic transducers described herein may be employed to great advantage in vending machines to replace the electrical coin switches heretofore employed. The necessity for fine adjustment of biasing means of electrical switches is eliminated, and the transducers can therefore be readily mass produced by assembly line techniques. Moreover, whereas the prior art electrical switches frequently encountered problems regarding signal "break-up," "cheating," and contact maintenance, which could only be solved by time consuming adjustments, the present invention eliminates these problems.

It should also be understood that the embodiments described herein are merely exemplary of the preferred practices of the present invention and that various changes, modifications, and variations may be made in the arrangements, operations and details of construction of the elements disclosed herein without departing from the spirit and scope of the present invention.