Abstract:
A vending machine includes a vend sensor for detecting a completion of a vend operation. The vend sensor includes an electronic circuit connected to first and second sound elements positioned on opposing sides of a product delivery chute of the vending machine. The first sound element directs a sound beam across the product delivery chute where it is received by the second sound element. During a vend operation, a product container is guided to the product delivery chute to be dispensed to a consumer. As the container passes through the product delivery chute, the sound beam is interrupted, thereby signaling the completion of a vend operation. Each of the first and second sound elements is provided with a cone that focuses the sound beam so as to limit interruptions stemming from outside sound sources.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of prior U.S. patent application Ser. No. 11/891,854 filed Aug. 13, 2007 now U.S. Pat. No. 7,480,543 which is a continuation of prior U.S. patent application Ser No. 10/678,186 filed on Oct. 6, 2003, which claims the benefit of 60/415,771 filed on Oct. 4, 2002, which issued as U.S. Pat. No. 7,255,246 on Aug. 14, 2007. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention pertains to the art of vending machines and, more particularly, to an ultrasonic sensor for detecting passage of a product container to a delivery portion of the vending machine. 
     2. Discussion of the Prior Art 
     Traditional can and bottle vending machines utilize various motors to move mechanisms in the form of cams and the like. In turn, the mechanisms release stored product from within a stack or storage rack arranged within the vending machine. Typically, a consumer inserts currency into a receptacle and thereafter makes a product selection. At this point, a controller operates a delivery mechanism which delivers the selected product to the consumer. 
     In typical vending machines, once the vending operation is complete, a refund of the consumer&#39;s currency is not possible. Therefore, if the machine fails to dispense the product, the consumer must seek recourse with the vending machine company, or to the company that services the particular machine. In any event, return of lost money due to the machine&#39;s failure to dispense product is a laborious process, the cost of which generally exceeds the amount of the consumer&#39;s loss. 
     Therefore, there exists a need in the art of vending machines for a sensor to detect the occurrence of a vending operation. More specifically, there exists a need in the art for an ultrasonic sensor capable of determining that a dispensed product reaches the consumer. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a vending machine including a vend sensor for detecting the passage of a vended product. More specifically, the sensor includes an electronic circuit interconnected with a speaker and a microphone that operate at frequencies above human hearing. Product containers rolling, or passing between the speaker and the microphone decreases the volume, or changes a period, of a distinct sound generated from the speaker. The electronic circuit detects this change in signal and sends a product detect signal to a main controller. 
     In a preferred form of the present invention, the electronic circuit includes water resistant ultrasonic transducers that operate over a frequency range having a 40 kHz center frequency. Preferably, the electronic circuit includes a receiver, an amplitude detector, a phase detector, e.g., or Phase Lock Loop (PLL) semi-conductor chip, and a logic circuit to detect the presence or non-presence of the 40 kHz sound waves generated by the transducer. The receiver amplifies the signal and subsequently passes the amplified signal to the phase and amplitude detectors. Once received, the logic circuit determines if the signal has changed in period or if the signal strength is below a predetermined threshold. In this manner, the logic circuit can filter out background noise which may result in false positive signals. If the signal has changed in period or the signal strength is below a predetermined threshold level, an open collector transistor is toggled to conduct to ground. The open collector signal constitutes the vend detect signal sent to the main controller. 
     In further accordance with the preferred form of the invention, the speaker and microphone are housed in separate, axially aligned, cones, preferably formed from plastic. Each cone faces an opposing cone such that sound generated from the speaker housed in a speaker cone reaches the microphone housed in the microphone cone. With this arrangement, the cones focus the ultrasonic signal toward the receiver or microphone unit. Focusing in this manner generally boosts the volume of the transmitter which ultimately dampens the reception of background ultrasonic noise. 
     Additional objects, features and advantages of the present invention will become more readily apparent to one of ordinary skill in the art from the following detailed description of a preferred embodiment taken in conjunction with the following drawings wherein like reference numerals refer to corresponding ports in the several views. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of a vending machine showing a main door in an open position exposing internal structure of the machine including an ultrasonic vend sensor arranged in a product delivery chute in accordance with the present invention; 
         FIG. 2  is an enlarged view of the product delivery chute of the vending machine of  FIG. 1  showing the particular arrangement of the vend sensor of the present invention; 
         FIG. 3  is a exploded view showing the vend sensor of the present invention; 
         FIG. 4  is a diagram depicting a product passing the vend sensor of the present invention; and 
         FIG. 5  is a block diagram depicting the operation of the vend sensor of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With initial reference to  FIG. 1 , a vending machine  2  includes a cabinet frame  4  having top, bottom, side and rear walls  6 - 10  that collectively define a central cavity  14 . In a manner known in the art, a first pair of wheels or casters  16  and  17  are secured to a front edge portion of bottom wall  7  to facilitate the positioning of vending machine  2 . Of course it should be realized that a second pair of wheels (not shown) are also arranged on a rear portion of bottom wall  7 . A door  18  is pivotally mounted to cabinet frame  4  to selectively enable access to central cavity  14  in order to load various product containers or other commodities into vending machine  2 . Door  18  is provided with a locking mechanism, shown in the form of a threaded rod  19 , to retain door  18  in a closed position so as to prevent pilfering of the commodities from central cavity  14 . Door  18  is also provided with an opening  20  to enable a consumer to remove a vended product container or other commodity from vending machine  2 . 
     Central cavity  14  includes a storage section  21 , a dispensing section  22 , a delivery section  24  and a lower section  26 . Storage section  21  is provided to hold products in escrow until a vending operation is performed. Towards that end, storage section  21  is provided with a plurality of vertically extending column walls  32 - 36  which, together with side walls  8  and  9 , form a plurality of column or stack areas  40 - 45 . In the embodiment shown in  FIG. 1 , stack areas  40 - 45  constitute single stack columns. However, it should be understood that the present invention also encompasses vending machines having multi-stack columns. In any event, stack areas  40 - 45  are partitioned by walls  32 - 36  to contain, separate and support a plurality of generally cylindrical containers  49  which, in the embodiment shown, constitute soda cans. 
     As further shown in  FIG. 1 , dispensing section  22  is provided with a frontal support wall  60  having arranged thereon a plurality of vend motors, one of which is indicated at  65 . As will be discussed more fully below, a plurality of cradles (not shown) are arranged behind frontal support wall  60 . Actually, each column or stack area  40 - 45  is provided with an associated cradle (not shown) that is operated through a respective one of the plurality of vend motors  65 . Upon selection of a particular product container  49  or other commodity, one of the plurality of vend motors  65  is activated to rotate a respective cradle causing a product container  49 , corresponding to the selected product to emerge from vending machine  2 . That is, product container  49  is transported to a product delivery chute  70  provided in delivery section  24  which is exposed to opening  20  in door  18 . In order to maintain containers  49  in a refrigerated state, lower section  26  is provided with a cooling system  75 . In general, the above description is provided for the sake of completeness and to enable a better understanding of the invention. The present invention is particularly directed to the incorporation of a vend sensor for detecting that a product has been dispensed from vending machine  2 . 
     With particular reference to  FIG. 2 , product delivery chute  70  includes a back wall  90  that interconnects with first and second side walls  91  and  92 . Preferably, back wall  90  and side walls  91  and  92  slope downward and inward toward a bottom wall portion  93  which, in turn, is adapted to lead to opening  20 . In accordance with a preferred embodiment of the present invention, a vend sensor  100  is located in product delivery chute  70  to detect the passing of a product container  49  from storage section  21  to dispensing section  22 . More specifically, vend sensor  100  includes first and second sound elements  104  and  105  which, as will be discussed more fully below, establish a sound zone that extends across product delivery chute  70 . 
     Reference will now be made to  FIG. 3  in describing the specific structure of sound elements  104  and  105 . As shown, sound element  104  includes a sound device  110  which, in the embodiment shown, is constituted by a speaker or other sound emitter. Sound device  110  is positioned within a cone member  112  that operates to focus a sound beam which originates at sound element  104  and passes to sound element  105  having a sound device in the form of a microphone or sound receiver. Cone member  112  also provides a water resistant barrier for sound element  110 . More specifically, cone member  112  includes a first end  121 , a second end  122 , and a hollow main body portion  123  therebetween. In accordance with the most preferred embodiment of the present invention, second end  122  includes an angled face portion  130  which aids in positioning cone member  112  in product delivery chute  70 . Towards that end, angled face portion  130  is provided with a mounting bracket  136  having an aperture (not separately labeled) for receiving a mechanical fastener for securing cone member  112  to side wall  91 . Angled face portion  130  is also provided with a pair of opposing positioning ears  138  and  139  which combine with angled face portion  130  to establish a proper alignment between first and second sound elements  104  and  105 . In addition, second end  122  has formed therein a notch  140  that aides in focusing the sound beam to establish the sound zone that extends between first and second sound elements  104  and  105 . 
     As best illustrated in  FIG. 4 , first sound element  104  projects or emits a sound beam that is focused through cone member  112  and directed toward second sound element  105 , which has an associated correspondingly constructed cone member  112 . In this manner, a sound beam can be passed between first and second sound elements  104  and  105  to form a sound zone for the detection of products passing through product delivery chute  70 . Cone member  112  directs the sound beam in such a manner as to minimize the effects of outside interferences. First and second sound elements  104  and  105  are interconnected to a sensor electronic board or SEB  160  through first and second control leads  162  and  163 . SEB  160  supplies first sound element or speaker  104  with a sound signal of particular frequency through lead  162 . The sound beam passes from first sound element  104  across product delivery chute  70  to second sound element  105 . Once received by sound element  105 , the sound beam or, more accurately, a signal representative of the sound beam, is passed through lead  163  back to SEB  160 . In the event that the sound beam is interrupted or distorted, or second sound element  105  detects a change in the sound beam, SEB  160  passes a signal to a main control unit  180  through a control lead  182  to signal the completion of a vend operation. Once main control unit  180  receives the vend completion signal, currency is collected and any change passed to the consumer. 
     Referring to  FIG. 5 , SEB  160  includes an oscillator  190  that produces a sound signal preferably having a center frequency of approximately 40 kHz. The sound signal is passed to first sound element  104  which projects a sound beam to second sound element  105 . Upon receipt of the sound beam, a signal is passed through lead  163  to an amplifier  195 . Amplifier  195  amplifies, and then passes, the signal to a phase detector or PLL semiconductor chip  197  and an amplitude detector  198 . Phase detector  197  determines a particular period of the signal, while amplitude detector  198  determines a strength of the signal. Both the signal period and the signal strength are then passed to a logic circuit  200 . Logic circuit  200  detects the presence and period of the approximately 40 kHz frequency generated by oscillator  190 . More specifically, logic circuit  200  processes the signal and determines if the signal is periodic and whether the signal strength is above a predetermined threshold. If the signal is not periodic, such as through a Doppler shift resulting from a product container passing near to but not through the sound beam, or the signal strength is below the determined threshold, e.g., a product passes through and breaks the sound beam, a completion signal is passed through control lead  182  indicating completion of the vend operation. Upon receipt of the completion signal, main control unit  180  will cease operation of one of the plurality of vend motors  65 , collect deposited currency, return any change and terminate the overall vend operation. 
     At this point, it should be noted that vend sensor  100  also serves as an anti-pilfering device, signaling main control unit  180  of an attempt to retrieve a product or container from storage section  21  through delivery section  24 . That is, even if main control unit  180  is not monitoring or performing a vend operation, an interruption of the sound beam passing between first and second control elements  104  and  105  will be sensed by SEB  160 . SEB  160  will pass a signal indicative of the disruption in the sound beam to main control unit  180 . A disruption of the sound beam in the absence of a vend operation indicates an attempt is being made to retrieve product from vending machine  2  without payment. In the event that main control  180  receives such a signal, main control unit  180  will lock each vend motor  65  to prevent product containers  49  from being withdrawn from storage section  21 . Other alarms or pilfering protection could also be activated. 
     Through experimentation, it has been found that the presence of cones  112  enable the sound beam to pass across product delivery chute  70  with minimal outside interference. Unlike optical sensors which require a very narrow beam, cones  112  enable the use of a rather broad beam across a wider detection region. It has been found through experimentation that outside noises, such as jingling keys or coins, sharp knocks or the like, will not trigger a false dispensing signal. In fact, it has been shown that vend sensor  100  can be used to effectively and accurately detect the passages of products through a detection region even as much as 18 inches (45.72 cm). Finally, the accuracy provided by vend sensor  100  enables main control unit  180  to maintain an accurate count of product remaining in vending machine  2 . Therefore, when a particular product is exhausted, a signal can be provided to the consumer without the need for a sold-out paddle. This eliminates additional mechanical components in vending machine  2 . 
     Although described with reference to a preferred embodiment of the present invention, it should be readily apparent to one of ordinary skill in the art that various changes and/or modifications can be made to the invention without departing from the spirit thereof. For instance, the particular form of cones  112  could be altered so long as a focused sound beam is passed between the sound elements, while preferably being shielded from outside interferences. In addition, it should be understood that the passing of a product between the sound elements is but one way to indicate the completion of a vend operation. In the event that a flexible product delivery chute is used, products falling onto the chute could cause the sound elements to become misaligned. The misalignment of the sound elements could then represent the completion of the vend operation. In general, the invention is only intended to be limited to the scope of the following claims.