Patent Publication Number: US-9424446-B2

Title: Point of sale inductive systems and methods

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to inductive systems and methods at the point of sale and in other locations. 
     Point of sale systems can generally include a series of shelving units and associated signage. Gondola shelving units, for example, benefit from being inexpensive, reconfigurable, and capable of displaying a variety of products. Signage can include source information, product information and/or sale information to promote or otherwise draw attention to a corresponding product. For example, signage can include placards affixed to or placed proximate the corresponding shelving unit. 
     Point of sale systems have also benefited from recent improvements in product packaging. Contemporary product packaging increasingly utilizes RFID labels as one aspect of inventory control, anti-counterfeiting and/or tamper-proofing measures. Product packaging can also serve more traditional functions, including providing a secure housing for a product while also displaying product specifications, compatibility information, power requirements, and hardware requirements. 
     In addition, point of sale systems can include a network of check-out terminals to monitor product inventory. For example, known inventory control systems include a network of terminals having magnetic stripe readers, bar code readers, check acceptance systems and/or fraud detection systems. Such inventory control systems can automatically reorder a product when the store inventory falls below a given level or in anticipation of an increase in product demand. 
     While the aforementioned point of sale systems are widely accepted, they suffer from a number of shortcomings. For example, the ability to interact with the product is limited in many display and packaging designs. In addition, losses in battery charge can occur, particularly where a product remains in inventory for an extended period. The visual inspection of product quantities can also become necessary at the point of sale, as inventory control typically occurs at check-out, but not before. 
     Accordingly, there remains a continued need for improved systems and methods for promoting products and product information at the point of sale. In addition, there remains a continual need for improved systems and methods to leverage the benefits of existing inventory control systems and to improve product identification and automatic reordering at the point of sale, at home, and in other locations. 
     SUMMARY OF THE INVENTION 
     Embodiments of the invention provide inductive systems and methods for the identification, powering and control of products and product packaging. 
     According to one embodiment, systems and methods for monitoring product levels are provided. The system can include a product container having a product level sensor and a passive tuned circuit whose impedance varies based on the amount of product remaining. The system can further include an inductive reader having a primary coil to monitor the impedance of the passive tuned circuit. The system can be configured to monitor product levels for liquids, loose articles, and rolls of sheet material, for example. When product levels fall below a predetermined level, additional product quantities can be automatically reordered in some embodiments. 
     According to another embodiment, localized clusters of inductive readers are positioned at various locations throughout a home, a restaurant or other locations. For example, a localized cluster may be positioned in a refrigerator, in a laundry room, in a medicine cabinet, in a cleaning supplies closet, and/or in a cleaning supplies caddy. The inductive readers can be operable to determine both the identity of a product and the amount of a product remaining. In one embodiment, a localized cluster of inductive readers can monitor caloric consumption based on the amount of products remaining after a given period. In another embodiment, a localized cluster of inductive readers can assist in recipe preparation. In still another embodiment, a localized cluster of inductive readers can generate a shopping list based on remaining levels of food products in a pantry or elsewhere. 
     According to another embodiment, systems and methods for heating food products are provided. The system can include a product container having a temperature sensor and a passive tuned circuit whose impedance varies based on the temperature of the product container. The system can further include a primary coil to monitor the impedance of the passive tuned circuit associated with the product container. The system can be configured to provide a source of wireless power to a heating element associated with the product container when the temperature falls below desired levels. In some embodiments, the heating element can include a ferromagnetic material that reacts to a time-varying electromagnetic field. In other embodiments, the heating element can be electrically connected to a secondary tank circuit. 
     According to another embodiment, systems and methods for providing a source of wireless power to a portable heating appliance are provided. The system can include a contactless power supply and a portable appliance including a heating element electrically connected to a secondary coil. In one embodiment, the heating element is a ferromagnetic heating element. In another embodiment, the portable appliance is a cordless iron and the contactless power supply is incorporated into a stowable ironing board. In this embodiment, the cordless iron can include a passive identification circuit defining an inductive identification profile. 
     According to another embodiment, a product alignment system and method are provided. The system can include a display surface having one or more primary coils for providing a source of wireless power to a secondary coil in a product or product container. The system can include a guide plate to urge the product or product container to a position in alignment with the one or more primary coils. In one embodiment, only the leading product among a row of products will be in alignment with the one or more primary coils. In another embodiment, the one or more primary coils can provide a source of wireless power to an LED, a speaker, a battery or other device associated with the leading product or product container. 
     According to another embodiment, systems and methods for providing a source of wireless power to product packaging are provided. The system can include a product container having a secondary tank circuit electrically coupled to one or more visual elements, speaker elements or both. The visual elements can include one or more LEDs, OLEDs, LCD displays and e-ink displays, and the speaker element can include an electrostatic speaker, for example. In one embodiment, the secondary tank circuit can be formed on a printed label adhered to the product container. The printed label can include an upper portion supporting a load, and a lower portion supporting a secondary tank circuit. The upper portion can be sized to conform to a product container sidewall, and the lower portion can be sized to conform to a product container base. 
     According to another embodiment, systems and methods for wireless identification of a product are provided. The system can include a plurality of products or product containers each having one or more resonant circuits. An inductive reader can identify the product or the product container based on a resonant frequency of each resonant circuit and a numerical key. The numerical key can include a prime number assigned to each resonant frequency. In one embodiment, the resonant circuits can each include shielding layers to selectively vary the reflected impedance of a corresponding secondary coil. In another embodiment, the resonant circuits at least partially overlie each other to selectively vary the combined reflected impedance of the resonant circuits. 
     According to another embodiment, a printed secondary circuit is provided. The printed secondary circuit can include a substrate defining a perforation and a resonant circuit supported by the substrate across the perforation, where separation of the substrate along the perforation varies the inductive identification profile of the printed secondary circuit. The inductive identification profile can indicate a battery is in need of additional charge, while in other embodiments the inductive identification profile can indicate the desired temperature setting for an item within a product container. 
     According to another embodiment, a printed secondary circuit for a load is provided. The printed secondary circuit can include a non-conducting substrate, a first printed winding supported by the substrate and defining a inner diameter, and a second printed winding supported by the substrate and defining an outer diameter less than the inner diameter. The second printed winding can include first and second end portions for connection to a load. The first and second printed windings can be substantially coaxial, and the substrate can adhere to a product or product container. The first and second end portions can extend across portions of the first printed winding. The first and second printed windings can be disposed on one side of the non-conducting substrate or on opposing sides of the non-conducting substrate. 
     These and other advantages and features of the present invention will be more fully understood and appreciated in view of the description of the current embodiments and the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a circuit diagram of an inductive product monitoring system. 
         FIG. 2  is a perspective view of a product container including a passive product sensor circuit. 
         FIG. 3  is a side elevation view of a sprayer assembly including a passive product sensor circuit. 
         FIG. 4  is a block diagram of an inductive product monitoring system. 
         FIG. 5  is an exploded perspective view of a weight sensor circuit. 
         FIG. 6  is a circuit diagram of the weight sensor circuit of  FIG. 5 . 
         FIG. 7  is an exploded perspective view of a weight sensor circuit including a barrier membrane. 
         FIG. 8  is a perspective view of a rolled product including a passive product sensor circuit. 
         FIG. 9  is a perspective view of a roll form and a passive product sensor circuit. 
         FIG. 10  is a close-up perspective view of the roll form and a passive product sensor circuit of  FIG. 9 . 
         FIG. 11  is a perspective view of a rolled product tray and a passive product sensor circuit. 
         FIG. 12  is a perspective view of a rolled product including a curved inductive secondary. 
         FIG. 13  is a perspective view of a system of inductive readers positioned in various locations throughout a home or business. 
         FIG. 14  is a perspective view of a carrying tote. 
         FIG. 15  is a perspective view of a product storage mat. 
         FIG. 16  is a perspective view of a point of sale display. 
         FIG. 17  is a flow chart for operation of an inductive reader. 
         FIG. 18  is a circuit diagram of a printed temperature sensing circuit. 
         FIG. 19  is a circuit diagram of an inductive heater system. 
         FIG. 20  is a circuit diagram of the inductive heater system of  FIG. 19  including a re-resonator coil. 
         FIG. 21  is a circuit diagram of the inductive heater system of  FIG. 19  including resonant circuits having resistive and bypass elements. 
         FIG. 22  is a circuit diagram of resonant circuits formed on a removable tear tab. 
         FIG. 23  is a diagram of a resonant circuit of  FIG. 22  including a ferromagnetic heating element. 
         FIG. 24  is a side view of multiple layered resonant circuits. 
         FIG. 25  is a diagram of a resonant circuit of  FIG. 24  without a series resonant capacitor. 
         FIG. 26  is a diagram of a resonant circuit of  FIG. 25  without a removable tear tab. 
         FIG. 27  is a diagram of a resonant circuit of  FIG. 26  with printed shielding. 
         FIG. 28  is a diagram of a inductive heater system having a temperature sensor circuit. 
         FIG. 29  is a diagram of the inductive heater system of  FIG. 28  including a re-resonator circuit. 
         FIG. 30  is a diagram of an inductive heater system having a portable load device. 
         FIG. 31  is a diagram of the inductive heater system of  FIG. 30  including first and second re-resonator circuits. 
         FIG. 32  is a diagram of an inductive heater system having a temperature sensor circuit. 
         FIG. 33  is a diagram of the inductive heater system of  FIG. 32  including a re-resonator circuit. 
         FIG. 34  is an illustration of a cordless iron and ironing board including a contactless power supply. 
         FIG. 35  is a diagram of the contactless power supply of  FIG. 34 . 
         FIG. 36  is a first process flow chart for operation of the contactless power supply of  FIG. 34 . 
         FIG. 37  is a second process flow chart for operation of the contactless power supply of  FIG. 35 . 
         FIG. 38  is an illustration of an inductive heating system for a portable device. 
         FIG. 39  is an illustration of the inductive heating system of  FIG. 38  including a secondary control unit to simultaneously energize a heating material and recharge a battery. 
         FIG. 40  is an illustration of a heating system for an article of footwear. 
         FIG. 41  is an illustration of a heating system for a hair straightener and curling iron. 
         FIG. 42  is an illustration of a heating system for a hair straightener and curling iron according to an alternative embodiment. 
         FIG. 43  is an illustration of a heating system for a hair straightener and curling iron according to an alternative embodiment. 
         FIG. 44  are top and side views of a product alignment system. 
         FIG. 45  is a first front view of the product alignment system of  FIG. 44 . 
         FIG. 46  is a second front view of the product alignment system of  FIG. 44 . 
         FIG. 47  is a circuit diagram of a point of sale display system. 
         FIG. 48  is a diagram of the point of sale display system of  FIG. 47  including a sensor and electronics circuit; 
         FIG. 49  is a diagram of the point of sale display system of  FIG. 47  including a sensor circuit. 
         FIG. 50  is a schematic view of a printed speaker circuit. 
         FIG. 51  is a schematic view of a multi-coil, multi-frequency tuned circuit. 
         FIG. 52  is a schematic view of the multi-coil, multi-frequency tuned circuit of  FIG. 51  including an LCD output. 
         FIG. 53  is a flow diagram illustrating operation of a contactless power supply for the multi-coil multi-frequency tuned circuit of  FIGS. 51-52 . 
         FIG. 54  is a perspective view of a point of sale system including multiple sensors. 
         FIG. 55  is a perspective view of a product or product container including printed conductive contacts. 
         FIG. 56  is a first diagram of the battery container of  FIG. 55 . 
         FIG. 57  is a second diagram of the battery container of  FIG. 55 . 
         FIG. 58  is a circuit diagram of a microcontroller-controlled contactless power supply. 
         FIG. 59  are schematic views of a multi-winding shielded identification circuit. 
         FIG. 60  is a schematic of a first device identification system. 
         FIG. 61  is a schematic of a second device identification system. 
         FIG. 62  is a schematic of the device identification system of  FIG. 61  including a substrate for heating the contents of a package. 
         FIG. 63  is a schematic of the device identification system of  FIG. 61  including printed secondary circuit. 
         FIG. 64  is a diagram of a first ink printed secondary circuit. 
         FIG. 65  is a diagram of a second ink printed secondary circuit. 
         FIG. 66  is a diagram of a printed resonant circuit formed on a pliable tab. 
         FIG. 67  is a diagram of a printed resonant circuit including a pressure switch. 
         FIG. 68  is a circuit diagram of a printed resonant circuit having resistive elements and bypass elements. 
         FIG. 69  is a side view of multiple layered resonant circuits. 
         FIG. 70  is a diagram of the printed resonant circuit of  FIG. 67  without a bypass element. 
         FIG. 71  is a diagram of the printed resonant circuit of  FIG. 70  including printed shielding. 
         FIG. 72  is a diagram of a first multi-layer resonant circuit supported by a package container. 
         FIG. 73  is a diagram of a second multi-layer resonant circuit supported by a package container. 
         FIG. 74  is a diagram of a printed product count sensor. 
         FIG. 75  are schematic diagrams of kitchen appliances including wireless power readers. 
     
    
    
     DESCRIPTION OF THE CURRENT EMBODIMENTS 
     The embodiments of the present invention provide wireless power systems and methods related to the identification, powering and control of products at the point of sale and in other locations. 
     I. Product Monitoring Systems 
     In a first aspect of the invention, a system for monitoring product levels is provided. The system can include an inductive reader and a product container having a passive identification circuit and a product quantity sensor circuit. The inductive reader can be operable to identify the product and product quantity based on the reflected impedance of the passive identification circuit and the product quantity sensor circuit, respectively. 
     According to a first embodiment, a system for monitoring liquid product levels is illustrated in  FIGS. 1-5  and generally designated  100 . The system includes an inductive reader  102  and a product container  104 . The inductive reader  102  can include a primary coil  106 , a driver  108 , a current sensor  110 , a microcontroller  112 , and a transmitter  114 . The driver  108  can be electrically connected to the primary coil  106  to drive the primary coil  106  across a range of operating frequencies. The microcontroller  112  can be electrically connected to the driver  108  to control the driver output, and hence the operating frequency. The current sensor  110 , optionally a hall effect current sensor, generates an electrical output proportional to the current in the primary coil  106 . In use, the driver  108  can sweep through a predetermined range of frequencies while monitoring the reflected impedance from a nearby inductive secondary. When the current in the primary coil  106  achieves a threshold value, a local maxima, or other criteria as measured by the current sensor  110 , the microcontroller  112  can record the corresponding operating frequency or frequencies in non-volatile memory. As explained below, this operating frequency or frequencies can correspond to a unique inductive identification profile and/or a measure of the remaining liquid. With reference to a look-up table stored in memory, the microcontroller  112  can identify the liquid and the amount remaining. 
     As also shown in  FIG. 1 , the product container  104  includes a passive product identification circuit  116  and a passive product sensor circuit  118 . The passive product identification circuit  114  can include one or more isolated resonant circuits  120 ,  122 . Each isolated resonant circuit, shown as a LC circuit having an inductor  124  and a capacitor  126 , contribute to the inductive identification profile of the product container  104 . That is, the isolated resonant circuits  120 ,  122  can generate a reflected impedance in response to a time varying current in a nearby primary coil  106 . The inductive reader  102 , and in particular, the current sensor  110 , can monitor the reflected impedance to identify one or more unique resonant frequencies corresponding to the isolated resonant circuits  120 ,  122 . Each resonant frequency can be a result of tuned inductance, tuned capacitance, or both. The microcontroller  112  can identify the container  104 , and therefore its contents, by comparing the detected resonant frequencies of the passive product identification circuit  116  with a look-up table stored in memory. The unique resonant frequencies of the resonant circuits  118 ,  120  can also allow for the creation of a number of unique identification codes, explained in greater detail in Part VII below. 
     The passive product sensor circuit  118  can include a secondary coil  128 , a variable resistor  130 , and a series capacitor  132 . In the illustrated embodiment, the resistance of the passive product sensor circuit  118  varies as a function of the volume of liquid remaining. In other embodiments, the inductance, capacitance, or both may vary. As shown in  FIG. 2  for example, the product container  104  can further include a base  134 , at least one upward extending sidewall  136  terminating in a periphery or opening  138 , an inductive winding  140 , and first and second conductors  142 ,  144  electrically connected to opposing end portions of the inductive winding  140 . The first and second conductors  142 ,  144  can be substantially parallel to each other and generally upright in spaced apart relation. A resistive or capacitive element  146  can also be connected across the conductors  142 ,  144 . During use, the product container  104  may include a conductive fluid  148  defining an upper level  149 . The fluid  148  may be in the form of a liquid, a gel, or any other sufficiently conductive material. For example, the fluid may contain sufficient electrolytes to render it at least partially conductive. 
     The inductive winding  140 , conductors  142 ,  144 , and resistive or capacitive element  146  may be completely or partially coated with a flexible, waterproof material such as Mylar® film by DuPont of Wilmington, Del. The inductive winding  140  may be oriented in a substantially planar configuration to conform to the product container base  134 . Optionally, the inductive winding  140  can be integrally formed with the product container  104  during its manufacture. In one embodiment, the passive product sensor circuit  118  may be inserted into the product container  104  after the product container  104  is formed, as generally shown in  FIG. 2 . For example, the passive product sensor circuit  118  may be inserted into product container  104  by a user upon purchase of the product, and/or the passive product sensor circuit  118  may be integrated with a separable piece of the product container  104 . As also shown in  FIG. 3 , the passive product sensor circuit  118  may form part of a sprayer assembly  150  for a spray bottle. In this embodiment, the conductors  142 ,  144  are located on opposing sides of the supply tube  152 . The inductive winding  140  and resistive or capacitive element  146 , which may be printed and then insulated using additional ink or coatings, can be positioned at the base  146  of the supply tube  150 . As the level  148  of the conductive fluid decreases, the impedance of the passive product sensor circuit  118  will change. The change in impedance of the passive product sensor circuit  118  will affect the current measured in the primary coil  106  of the inductive reader  102 . The microprocessor  112  can then evaluate the reflected impedance in the primary coil  106  for a given product to determine the quantity of product remaining. For example, the microprocessor  112  can reference the reflected impedance to the feedback of the passive product identification circuit  116  to establish a relative reflected impedance. Using the relative reflected impedance, the microprocessor  112  can access a reflected impedance table for that particular product type. The microprocessor  112  may use the reflected impedance table to determine the product amount corresponding to the reflected impedance recorded by microprocessor  112 . The inductive reader  102  includes a low power transmitter  114  and antenna  115  to transmit the product amount and product type to a central hub  168 . In the event that a product type and reflected impedance data are not included in the lookup table, then new data may be uploaded to the inductive reader  102  through a setup screen graphical user interface (GUI) accessed from the central hub  168 . The inductive reader  102  may also include a predetermined identifier to distinguish the inductive reader  102  from other inductive readers. The identifier may be transmitted to the central hub  168  with the product information. These and other data transmissions may be accomplished through hard-wired networks, wireless technology, or other suitable communication system. 
     With reference to  FIG. 4 , the central hub  168  can include a receiver  170  to receive information relating to the product amount, the product type, the sensor type, the reference data and the unique inductive reader identifier from the transmitter  114 . The receiver  170  can be connected to a low power transmitter  172 , which transmits the product and reader information to a network server  174 . The central hub  168  can be programmed through a setup screen to link unique user profile identifiers to the entire system or to individual inductive readers  102 . As also shown in  FIG. 4 , a network server  174  includes a receiver  176 , data applications  178  and data storage  180 . The receiver  176  receives the product and user information from the transmitter  172 . The information is transmitted to data storage  180 , which may include a user account for each unique user profile. The data applications  178  can include software that processes the product amount to determine if a variety of actions should be taken. For example, the amount of product, the consumption rate, and the timing of upcoming store visits may be used to determine whether the product should be added to the shopping list. If the product should be added to the shopping list, an e-mail or text message alert may be sent to the user to indicate that the product is low, the product may be automatically added to a digital shopping list, or the product may be automatically reordered. If the product does not need to be added to the shopping list, the network server  174  may still update data storage  180  with the current levels of all products being monitored. This may also include information regarding product usage, budgeting, value shopping, meal and caloric intake planning, product service planning, and prescription tracking. This information may be retrievable through a webpage or any other information system suitable to the application. 
     The network described above may be a low power network. An example of a low power network is disclosed in U.S. application Ser. No. 12/572,296, entitled “Power System” filed Oct. 2, 2009 by Fells et al, now U.S. Pat. No. 8,446,046, the disclosure of which is incorporated by reference in its entirety. In addition, the secondary coils may be aligned with the primary coil  106  through any alignment device suitable to the application including but not limited to mechanical alignment systems and magnetic alignment systems. An example of a suitable alignment system is disclosed in U.S. application Ser. No. 12/390,178, entitled “Magnetic Positioning for Inductive Coupling” filed Feb. 20, 2009 by Baarman et al, now U.S. Pat. No. 8,766,484, the disclosure of which is incorporated by reference in its entirety. 
     Because the inductive reader  102  “reads” a product  104  periodically, for example when a product is replaced, a very low power sense circuit can trigger a ping or sweep to read the product  104  then update the hub  168 , shutting down shortly thereafter. The addition of amplitude modulation allows one bit to be a reference while changing the amplitude of the remaining bits allows for additional combinations. Ranges can be established for sensors and identifiers along with bit positions and sensor classifications and reference frequency information to assure a proper and simple understanding of the returned values. Using multiple frequencies as bits, a resonant frequency can be used to represent a first binary value while the absence of a resonant frequency can represent a second binary value. This allows a very large sequence of possibilities as set forth in Part VII below. This identification method can be augmented utilizing fewer coils to get more possible combinations using more bit locations or frequencies than coils. 
     A product monitoring system constructed in accordance with another embodiment is illustrated in  FIGS. 5-7  and generally designated  182 . The product monitoring system  182  is similar to the product level sensor  100  set forth above, with the addition of a passive product sensor circuit  184  whose impedance varies as a function of the weight of a product. 
     More particularly, the product weight sensor  184  includes a spiral planar secondary coil  128  aligned with the primary coil  106  in the inductive reader  102 . An electrically conductive compressible pad  186  is connected in parallel with the secondary coil  128 . The pad  186  may be made of any flexible electrically conductive material, including but not limited to foam. The product level sensor circuit  118  can include a first electrical contact  188  located on one side of the pad  186  and a second electrical contact  190  located on the other side of the pad  186 . The product weight sensor  184  may be integrally formed with product container  104  during its manufacture. Alternatively, the product weight sensor  184  may be inserted into the product container  104  after the product container  104  is formed. Further optionally, as shown in  FIG. 5 , the product weight sensor  184  may be located outside of product container  104  such that product container  104  is positioned on top of product weight sensor  184 . As shown in  FIG. 7 , the product monitoring system  100  may include a barrier membrane  192  to prevent the product from directly contacting the product weight sensor  184 . The product weight sensor  184  may also include an assembly cover  194 . 
     When the product container  104  is empty, the impedance of the product level sensor circuit  118  is at an initial value. As product  148  is added to the product container  104 , the total weight on the top surface of the pad  186  increases. As the pad  186  flexes under the weight of the added product  148 , the two electrical contacts  188 ,  190  approach one another. As the contacts  188 ,  190  move closer to one another, the impedance of the product level sensor circuit  118  changes. As described above, the impedance of the product level sensor circuit  118  may be monitored by measuring current in the primary coil  106 . The product amount, product type and unique inductive reader identifier may be transmitted to the central hub  168  and to the network server  174  substantially as set forth above. In a variation of this embodiment, the product level sensor circuit  118  can include a conductive membrane whose impedance varies as the membrane flexes under the weight of the added product  148 . The varied impedance can correlate to diminished liquid quantities in a manner substantially as set forth above. 
     A product monitoring system constructed in accordance with another embodiment is illustrated in  FIGS. 8-12  and generally designated  200 . The product monitoring system  200  is similar to the product level sensor  100  set forth above, with the addition of a passive product sensor circuit  202  whose impedance varies as sheets are removed from a roll of sheet material  204 . 
     The product roll  204  can include a rolled product  206 , a roll form  208 , and at least one perforation  210 . The roll form  208  may be formed of paperboard or other suitable material. The perforation  210  allows for separation of the product roll  204  into smaller rolls. As shown in  FIGS. 9-10 , the rolled product sensor  202  is supported by the roll form  208  and includes first and second conductors  212  arranged in a substantially parallel orientation and extending the length of the roll form  208 . At least one resistive or capacitive element  214  can connect the conductors  212  in each perforated section of product roll  204 . As the product roll  204  is used and perforated sections are removed, the resistive or capacitive elements  214  connecting the conductors  212  for that perforated section are also removed from the circuit. The removal of resistive or capacitive elements  214  can cause the impedance on an inductive secondary  128  to change. As described with regard to the above embodiment, the impedance of the inductive secondary  128  may be monitored by an inductive reader  102  to determine a product quantity. The product amount, and optionally the product type and the unique inductive reader identifier, may be transmitted to the central hub  168  and to the network server  174  substantially as set forth above. 
     Referring now to  FIG. 11 , the product monitoring system  200  may also include a rolled product tray  216 . The rolled product tray  216  can include six sockets 218 sized to receive a product roll  204 . Each socket  218  can include first and second leads  220  for electrical connection to the first and second conductors  212  when a roll form  208  is received within a corresponding socket  218 . The first and second leads  220  can be connected to a substantially planar secondary coil  222 . The secondary coil  222  can be aligned with a primary coil  224  substantially as set forth above. 
     A variation of this embodiment is shown in  FIG. 12 . In this variation, the passive product sensor circuit  202  may include conductors  212  that are integrated into the product or positioned on a face of the product  206 . At least one resistive or capacitive element  214  optionally connects the conductors  212  on each individual sheet of the product  206 . If the product is perforated in the axial direction to separate individual sheets, a predetermined number of resistive or capacitive elements  214  may be used per sheet of product. If the product is not perforated, a predetermined number of resistive or capacitive elements  214  may be used for a certain length of product. In this configuration, as product is used, the resistive or capacitive elements  214  may be removed from the circuit  202 . As resistive or capacitive elements  214  are removed, the impedance of the circuit  202  can change. As also shown in  FIG. 12 , the primary coil  224  and the secondary coil  222  may be curved, substantially matching the curvature of the surface of roll form  208 . This configuration can allow further optional placement of the secondary coil  222  on the inner or outer surface of roll form  208  and placement of the primary coil  224  on the inner or outer surface of a roll holding rack. A product roll  204  in accordance with this configuration may be connected to the rolled product tray  216  and the product amount may monitored substantially as set forth above. In this manner, rolled product monitoring systems in accordance with the embodiments of  FIGS. 8 and 12  may be secured on the rolled product tray  216  of  FIG. 11  at the same time. Optionally, the embodiments of  FIGS. 8 and 12  may be combined such that the number of rolls in a stack and the number of stacks in a bulk package may be monitored. 
     II. Inductive Reader Systems 
     In a second aspect of the invention, localized clusters of inductive readers are positioned at various locations throughout a home, business or other location. The inductive readers are operative to determine both the identity of a product and the amount of product remaining. In some applications, the inductive readers can provide information to a user based on the historical use of a given product. For example, the inductive readers can provide nutritional consumption data and can generate a shopping list based on the remaining quantities of food supplies in a food pantry or elsewhere. 
     A system of inductive readers in accordance with one embodiment is illustrated in  FIGS. 13-15  and generally designated  300 . The system  300  includes localized clusters of inductive readers operating independently and transmitting their product identification, product amount and unique inductive reader identifier to a centralized hub  302 . The centralized hub  302  can transmit aggregated product and user information to a network server  304  through any suitable device such as a Wi-Fi broadband router and modem  306 . 
     The inductive readers may be in various locations throughout a home, a business or other location. Readers may be located in a refrigerator storage surface  308 , in a cabinet storage surface  310 , in a shower storage surface  312 , in a laundry room storage surface  314 , and in a tote  316  for reading a variety of products  318 . Each reader may be represented by a unique profile identifier in the setup GUI for the central hub  302 . As shown in  FIG. 15 , a portable storage mat  320  may be temporarily placed in a variety of locations. The storage mat  320  and any of the other inductive readers may include multiple primary coils  106  such that at least one primary coil  106  is sufficiently aligned with each product package to identify and determine the amount of each product. The secondary coils  128  in the product package may be aligned with the primary coils  106  using an alignment system substantially as set forth above. As also set forth above, the inductive readers may identify the product, determine the product amount, and transmit this information with an inductive reader identifier to the central hub  302 . The central hub  302  may transmit the product and user information to a network server  304 , which may transmit the information to a computer  322 , a handheld electronic device  324 , or a other network server through a broadband internet connection or any other communications architecture for transferring electronic data. 
     Localized clusters of inductive readers may also be used to monitor food storage locations and/or cooking appliances to determine the caloric intake or other nutritional data relating to the food consumed in a household. In this configuration, the data applications  178  noted in Part I above can include software that manipulate the product amounts to calculate the total calories consumed over a period of time, the average calories consumed over a period of time and/or other useful nutritional information. Data applications may also monitor a variety of other personal health indicators and home security, for example. 
     In another variation as shown in  FIG. 16 , display units  330  in grocery stores, department stores or other similar businesses may be equipped with inductive readers  102 . Data gathered by the inductive readers  102  regarding the number of products located on the display unit may be used to track inventory, drive active display signage or trigger reordering for the store&#39;s purchasing department. Optionally, the display unit  330  can include shelving and other conventional display surfaces  332 , where the primary coil(s)  334  of the inductive reader  102  is positioned adjacent a surface of the display surface  332 , for example, within the display shelving  332 . As also illustrated in  FIG. 15 , the display unit  330  can include a single oval-shaped primary winding  334  extending vertically or horizontally beneath a surface of a display unit  330 , or can include multiple primary coils  334  positioned beneath a surface of a shelving unit  330 . The shelving units may themselves receive power inductively, or may receive power through a conventional mains connection. 
     In another embodiment, a product monitoring system for a point of sale display  332  includes an inductive reader  102  and a plurality of product containers  104  each optionally supported by the point of sale display. The inductive reader  102  can include a primary tank circuit, and each of the product containers  104  can include an impedance element. The inductive reader  102  can be adapted to detect a change in a characteristic of power in the primary tank circuit in response to (1) the addition of a product container including an impedance element to the point of sale display and/or (2) the removal of at least one of the plurality of product containers from the point of sale display. The characteristic of power can include one of voltage, current and phase. The plurality of product containers  104  can define a cumulative impedance, and the inductive reader  102  can be adapted to detect a change in the reflected cumulative impedance corresponding to a change in the characteristic of power in its primary tank circuit. For example, the inductive reader  102  can detect an increase in the cumulative reflected impedance in response to placement of a product container  104  (optionally among other product containers) in the vicinity of the inductive reader  102 . The inductive reader  102  can also detect a decrease in the cumulative reflected impedance in response to removal of a product container  104  from the vicinity of the inductive reader  102 . The impedance element can include a capacitive element, an inductive element or a resistive element for example. Optionally, the impedance element can form part of a secondary circuit  116 , for example a passive identification circuit  116  having a secondary coil and a series capacitor. The impedance can be the same for each of the plurality of product containers  104 , or can differ with respect to each other. The point of sale display can include a shelving unit or wall rack  332  or other device to support a plurality of product containers. The point of sale display can define a depth, width and/or height, and the primary tank circuit can include a primary coil  334  extending substantially along the respective depth, width and/or height of the point of sale display to simultaneously monitor products along one or more rows or columns. The inductive reader  102  can be adapted to transmit information based on the cumulative reflected impedance to a central hub  168 . The central hub  168  can include a memory adapted to maintain historical product inventory levels as product containers  104  are added to or removed from the point of sale display. The product monitoring system can also be used in conjunction with a primary coil  624  and associated power supply  632  as set forth more fully in Part V below. For example, the product monitoring system can include a inductive reader  102  for monitoring product level inventory on a point of sale display  332  and a contactless power supply  624  for providing power to substantially only the leading product on a point of sale display  332 . 
     The product monitoring system described above can be utilized across a wide range of applications. For example, a central hub  168 , network server  174  or other data logger in communication with a network of inductive readers  102  can record point of sale inventory levels throughout a monitoring period, for example a 24 hour monitoring period. The recorded point of sale inventory levels can be used to trigger product re-stocking, particularly if point of sale inventory levels fall below a predetermined quantity. The recorded point of sale inventory levels can also be used to track periods where less than the desired number of product containers are on display at the point of sale. This information can be provided to the manufacturer, for example, who may be interested in knowing whether or not its products are continuously stocked on store shelves. The recorded point of sale inventory levels can also be used to track the sale of products according to their expiration dates, and can trigger the removal or discounting of products that have reached or are nearing expiration. The recorded point of sale inventory levels can include product quantity levels categorized by product identifier, inductive reader identifier, expiration date and/or shelving unit, for example. While described above in relation to product containers for the point of sale, the product monitoring system can also be utilized in other applications, including for example warehouse inventory, assembly plants, parcel processing, and can pertain to products apart from a container. 
     Additional embodiments include inductive readers  102  in combination with check-out terminals, laundry appliances, stoves and microwave appliances. For example, a check-out terminal can include an inductive reader  102 , optionally to replace or augment a conventional bar-code reader. The inductive reader  102  can include one or more primary coils  106  operable at a plurality of frequencies to identify products based on the resonant frequency or the reflected impedance of one or more associated resonant circuits  120 . The inductive reader can then identify an item in response to the resonant frequency of the resonant circuit approximately corresponding to one of the plurality of reader circuit operating frequencies. As a further benefit of the present invention, the primary coil can be utilized to disable a security tag. Alternatively, a washer and/or dryer unit can include an inductive reader to identify clothing having inductive identification circuits printed on a corresponding clothing tag. The present embodiment can also facilitate tracking of particular articles of clothing in combination with a central hub as described above. 
     One or more inductive readers  102  may also be used in combination with various other appliances or locations, including microwaves, cooking ranges, and kitchen countertops. To reiterate, an inductive reader can monitor and aggregate the nutritional value of food as it is removed from the pantry and/or refrigerator. For example, the system  300  can calculate periodic caloric consumption values for a given household. Alternatively, or in addition, the system  300  can assist in the preparation of a recipe. For example, a user can upload a recipe to an inductive reader associated with a stove with the aid of a passive identification circuit  116  affixed to the recipe label. A computer can then monitor the combination of ingredients and cooking times according to the recipe, providing instructions such as when and how much of a given ingredient to add. As ingredients are consumed, the computer can compile a list of groceries for replenishment. 
     A flow chart illustrating a product level sweep circuit for an inductive reader system  300  is shown in  FIG. 16 . The system begins in a wake state at step  340 . At step  342 , the system  300  sweeps each primary coil  334  for a product identification. When a resonant frequency is encountered, the level of current in the primary coil  334  can increase above a baseline current established by the feedback or average feedback of the product identification coils. The system then queries if there are product identifications present at step  344 . If at step  344  there are no identified products within a vicinity of the primary coil  334 , the network sleeps for a pre-determined amount of time at step  346 . If there are product identifications present, the network determines the amount of each product remaining at step  348 . The network will then transmit the product identifications, the amount of each product, and optionally a unique inductive reader identifier to the hub at step  350 . 
     III. Product Container Heater Systems 
     According to a third aspect of the invention, a system for heating a product container is provided. The system can include a product container having a passive identification circuit and passive temperature sensing circuit whose impedance varies based on the temperature of the product container and/or its contents. The system can further include a contactless power supply adapted to monitor the reflected impedance of the passive identification circuit and the passive temperature sensing circuit. The product container can include any container for supporting a food item, a beverage item, an oil, a topical cream or other item in any form as desired. While described as pertaining to a product container, the embodiments can also be adapted for use with a portable appliance, such as a curling iron or a hair straightener as set forth more fully in Part IV. 
     Referring now to  FIG. 18 , a container  360  is shown as including a temperature sensing circuit  362  and a ferromagnetic material  364 . Though shown as a container for a heated beverage, the container  360  can be utilized in connection with food products, lotions, serums and therapy ointments, for example. In some embodiments, the container  360  itself can be formed of a ferromagnetic material  364 , while in other embodiments a ferromagnetic material  364  can be applied to a surface of the container  360 . The container  360  can also include one or more insulating materials, including, for example, a polystyrene foam material or a paperboard material, optionally substantially encompassing the ferromagnetic material  364 . The insulating materials can also include a dielectric ink, such as an ELECTRODAG® dielectric ink by Henkel Corporation of Irving, Calif., to form a protective layer on one or more surfaces of the ferromagnetic material  364 , the temperature sensing circuit  362 , or both. 
     The temperature sensing circuit  362  can be formed on a flexible, non-conductive substrate, and can include an inductive element  366 , a series resonant capacitor  368 , and a series variable resistor  370 . The inductive element  366  can include a printed trace winding, and the series resonant capacitor  368  can be selected to have a capacitance such that the temperature sensing circuit  362  includes a resonant frequency corresponding to a driving or operating frequency of a contactless power supply. The inductive element  366  and/or other printed conductive elements can be formed from Vor-ink™ by the Vorbeck Materials Corporation of Jessup, Md. The variable resister  370  can include a thermistor or other element having a resistance as a function of a temperature of the container  360  or its contents. The non-conducting substrate can be applied to an exterior surface of the container  360  using an adherent, for example a pressure-sensitive adhesive (PSA). 
     In the present embodiment, a contactless power supply provides power to the container  360  to at least indirectly and optionally directly heat the container contents. In particular, the contactless power supply can determine whether and to what extent additional heating is desired by sweeping through a predetermined range of frequencies while monitoring the reflected impedance of the temperature sensor circuit  360 . Because the resistance of the thermistor  370  can vary greatly with temperature (generally more than standard resistors), the contactless power supply will experience variations in the current and/or voltage in the contactless power supply primary tank circuit across the range of operating frequencies. When the current in the primary tank circuit passes a threshold value, a controller in the contactless power supply is able to record the frequency at which the event occurred, and correlate that frequency to a temperature of the container  360  or its contents using a look-up table. When the temperature of the container  360  or its contents is determined to be less than the desired temperature, the contactless power supply can provide a suitable time varying voltage across the primary tank circuit to heat the ferromagnetic material  364  and the corresponding container contents. 
     An inductive heating system for a product container or a portable device in accordance with another aspect of the invention is illustrated in  FIG. 19-20 . The inductive heating system includes a contactless power supply  380  and a product container  400 . The contactless power supply  380  includes a power supply  382 , an inverter  384  electrically coupled to the output of the power supply  382 , and a tank circuit including a series capacitor  386  and primary coil  388 . In addition, a controller  390  is electrically connected to a mains input, the power supply  382 , the inverter  384 , and the tank circuit for controlling a characteristic of the power applied to the primary coil  388 . In particular, the controller  390  selectively controls the frequency at which power is generated in the primary coil  388 . In operation, the contactless power supply  380  applies power to the primary coil  388  at an identification frequency and then evaluates the reflected impedance of the product container using a current or voltage sensor. If the product container  400  has a resonant frequency at the identification frequency, then the contactless power supply  380  can recover operating parameters from memory to directly or indirectly power a heater element within the product container  400 . 
     In the present embodiment, the product container  400  includes three isolated resonant circuits  402 ,  404 ,  406  and a ferromagnetic material  408 . The ferromagnetic material  408  can be in the form of a slab, strip, or coating on a surface of the product container  400 . Alternatively, the product container  400  can itself be formed of a ferromagnetic material. The ferromagnetic material  408  may include a distinct currie-point temperature at which it no longer reacts to the inductive magnetic field, effectively placing imposing a maximum temperature on the device or package being heated. The selection of material and specific currie-point temperature is application specific and may be beneficial in situations where the product requires a specific temperature or in situations where the maximum temperature should be regulated for safety reasons. As described above, the contactless power supply  380  determines the identity of the product container  400  by sweeping through a predetermined range of frequencies while monitoring the current, voltage or phase in the primary coil  388 . The isolated resonant circuits  402 ,  404 ,  406  in the product container  400  react differently to the contactless power supply  380  depending on the frequency applied to the primary coil  388 . The different reactions of the resonant coils  402 ,  404 ,  406  cause varying current, voltage or phase in the primary coil  388 . For example, when the current in the primary coil  388  exceeds a threshold value, or achieves a local maxima or other criteria, the controller  390  is able to record the frequency at which the event occurred. By sweeping through a range of frequencies, the contactless power supply  390  is able to determine and record an inductive identification profile optionally including the resonant frequencies of each of the isolated resonant circuits  402 ,  404 ,  406 . The controller  390  is then able to translate the inductive identification profile into a unique device or package identification code as set forth in Part VII. The contactless power supply  380  then utilizes the identification code to provide power to the container  400  according to the specific needs of the container  400  and the contents therein. Power applied by the contactless power supply  380  can then induce eddy currents in the ferromagnetic strip  408  to heat the product container  380 . As optionally shown in  FIG. 20 , the contactless power supply  380  can include an isolated re-resonator coil  392  that acts to shape, focus, redistribute or boost the inductive field strength when heating the product container  400  in order to increase the spatial freedom for alignment of the product container  400  and contactless power supply  380 . 
     In another embodiment as shown in  FIGS. 21-22 , the isolated resonant circuits  402 ,  404 ,  406  each include a series resistive element  410  and a bypass element  412  to short the resistive element  410 . The configuration of the resistive element  410  and the bypass element  412  may be set at manufacture or may be selectable by a vender or by an end-user of the product container  400 . For example, physical switches may be employed to select the state of the bypass element  412 . The physical switches may be push-buttons, a multi-pole slider switch, or a multi-pole rotary switch. Alternatively, the isolated resonant circuits  402 ,  404 ,  406  may be formed from conductive ink on a non-conducting substrate  414  forming a portion of the package  400 , where the bypass element  412  is opened in response to the separation of a portion of the non-conducting substrate  414  from the remaining package  400 . These can be sealed by another layer of protective ink, label or coating. In the event that the user desires to open one of the bypass elements  414 , a user can tear off a designated portion of the package along a perforation  416 . As shown below in Table 1, the state of the resonant circuits  402 ,  404 ,  406  can indicate the desired temperature of a food product within the product container  400 , where “High” indicates the bypass element of the corresponding resonant circuit has been opened by the user: 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Selected Product Container Temperature 
               
            
           
           
               
               
               
               
            
               
                 Resonant 
                   
                   
                   
               
               
                 Circuit 1 
                 Resonant Circuit 2 
                 Resonant Circuit 3 
                 Temperature 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 Low 
                 Low 
                 Low 
                 Off 
               
               
                 High 
                 Low 
                 Low 
                 100 
               
               
                 Low 
                 High 
                 Low 
                 140 
               
               
                 Low 
                 Low 
                 High 
                 180 
               
               
                   
               
            
           
         
       
     
     As optionally shown in  FIG. 23 , an isolated resonant circuit  420  can include a trace winding  422  formed on a non-conductive substrate  430 , a printed ink capacitor  424 , a carbon printed resistive element  426 , a bypass element  428  formed on a perforated portion of the substrate  430 , and a printed ink jumper  432  to interconnect end portions of the trace winding across a printed ink insulated layer  434 . A portion of the substrate includes a tear tab  436 , the removal of which opens the bypass element  428  to allow current to flow through the carbon printed resister  426 , thus changing the reflected impedance of the isolated resonant circuit  420 . In the manner as described above, the contactless power supply  380  can identify the product container  400  based on the resonant frequency or the reflected impedance of the isolated resonant circuit  420 , and can provide inductive power to the heating element  408  based on the presence or absence of the tear tab  436  from the product container  400 . This embodiment can be useful, for example, in providing the desired amount of heat to a food product, e.g., a can of soup, contained within the product container  400 . The temperature may be initially set by the product ID and the selection may allow an offset to this base level. In addition, the isolated resonant circuits can overlie each other on a packaging material as shown in  FIG. 24 . As shown in  FIG. 24 , the isolated resonant circuits  402 ,  404 ,  406  are separated by corresponding layers of insulating ink  438 . As optionally shown in  FIG. 25 , the isolated resonant circuit  420  does not include the optional printed ink resonant capacitor. Multiple resonant circuits can be printed within a small space utilizing insulator layers and multiple circuit layers. Moreover, the ferromagnetic material  408  can form a core, or can be used in conjunction with a separate ferromagnetic core, as shown in  FIG. 26 . In this embodiment, both the tear tab  436  and the printed ink capacitor  424  are omitted to illustrate their optional inclusion in the isolated resonant circuit  420 . The isolated resonant circuit  420  of  FIG. 27  can further include a printed shielding material  440  to enhance the inductive coupling between the isolated resonant circuit  440  and the primary coil  388 . The shielding material can be utilized in combination with metal packages to isolate the coils from the metal package. For example, shielding inks can contain metal powders that can shield the coil from the metal package. The loading of non-conductive powder within these inks can impact the shielding properties along with the specific type of magnetic or metal properties. 
     In another embodiment as shown in  FIGS. 28-29 , the contactless power supply  380  provides power to a portable device  400 , for example a product container, to indirectly heat a surface of the portable device  400 . In this embodiment, the portable device includes a secondary coil  442  and series resonant capacitor  444  to form a secondary tank circuit, a rectifying and charging sub-circuit  446  connected to the output of the secondary tank circuit, a battery  448  connected to the output of the rectifying and charging sub-circuit  446 , a heater element  450  connected to the output of the battery  448 , a heatable surface  452  to receive heat from the heating element  450  by conduction, a temperature sensor  454  to detect the temperature of the heatable surface  452  and having an output, and a controller  456  connected to the output of the temperature sensor  454 . In this embodiment, the contactless power supply  380  does not directly heat a ferromagnetic material as discussed above in connection with  FIGS. 18-21 . Instead, the contactless power supply  380  provides power to the portable device  400  to charge the battery  448 , which provides the corresponding power to operate the heater  450  and heatable surface  452 . In this embodiment, the heater  450  can continue to operate when the device  400  is not in close proximity to the contactless power supply  380 . As optionally shown in  FIG. 29 , the contactless power supply  380  can include an isolated re-resonator coil  392  that acts to shape, focus, redistribute or boost the inductive field strength when powering the device  400  in order to increase the spatial freedom for alignment of the device  400  and the contactless power supply  380 . Additionally, charging and heating can occur simultaneously. 
     In another embodiment as shown in  FIGS. 30-31 , a portable device  400 , for example a product container, includes three isolated resonant circuits  460 ,  462 ,  464  and a portable device load  466 . In this embodiment, the contactless power supply  380  provides power to the portable load  466  using a secondary tank circuit  468  according to the reflected impedance of the isolated resonant circuits  460 ,  462 ,  464 . As described above in connection with  FIG. 21 , each isolated resonant circuit  460 ,  462 ,  464  includes a resistive element  470  and a bypass element  472 . When in a closed condition, the bypass element  472  effectively shorts the resistive element  470 , effectively changing the impedance of the corresponding isolated resonant circuit. The contactless power supply  380  can then provide power to the remote device  400  based on the change in impedance of the isolated resonant circuit(s). For example, the state of the “n” number of resonant circuits  460 ,  462 ,  464  can indicate which of 2 n  power levels should be applied to the portable device  400 . As shown in Table 2 below, “0” indicates the bypass element of the corresponding resonant circuit is in a non-conducting state, and “1” indicates the bypass element of the corresponding resonant circuit is in a conducting state: 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Selected Power Level 
               
            
           
           
               
               
               
               
            
               
                 Resonant 
                   
                   
                 Applied 
               
               
                 Circuit 1 
                 Resonant Circuit 2 
                 Resonant Circuit 3 
                 Power (mA) 
               
               
                   
               
               
                 0 
                 0 
                 0 
                 150 
               
               
                 1 
                 0 
                 0 
                 250 
               
               
                 0 
                 1 
                 0 
                 350 
               
               
                 1 
                 1 
                 0 
                 450 
               
               
                 0 
                 0 
                 1 
                 550 
               
               
                 1 
                 0 
                 1 
                 650 
               
               
                 0 
                 1 
                 1 
                 750 
               
               
                 1 
                 1 
                 1 
                 850 
               
               
                   
               
            
           
         
       
     
     Once desired the power level is selected, which can include the operating frequency, amplitude, duty cycle, pulse width, phase or other characteristic of power in the primary coil  388 , the contactless power supply  380  provides power to the portable device  400  to heat a surface of the portable device substantially as described above in connection with  FIGS. 28-29 . As optionally shown in  FIG. 31 , the contactless power supply  380  can include an isolated re-resonator circuit  392  that acts to shape, focus, redistribute or boost the inductive field strength when heating the remote device  400  in order to increase the spatial freedom for alignment of the remote device  400  and contactless power supply  380 . In like manner, the remote device  400  can include a re-resonator circuit  474 , shown as a series resonant circuit, to enhance reception of the inductive field generated by the contactless power supply  380 . 
     In another embodiment as shown in  FIGS. 32-33 , the remote device or product container  400  includes a resonant temperature sensor circuit  468 . In this embodiment, the resonant temperature sensor circuit  468  includes a secondary coil  442 , a series capacitor  444 , and a temperature sensor  454 . The temperature sensor can include a thermocouple, an analog to digital converter connected to the output of the thermocouple, and a variable impedance element connected to the output of the analog to digital converter. In operation, a change in the temperature of the ferromagnetic material  452  results in a change in the impedance of the resonant temperature sensor circuit  468 . In this embodiment, the contactless power supply  380  is operable to detect a change in the reflected impedance of the resonant temperature sensor circuit  468 , identify the corresponding change in temperature of the ferromagnetic material  452 , and adjust the power output, if necessary. As optionally shown in  FIG. 33 , the contactless power supply  380  can include an isolated re-resonator circuit  392  that acts to shape, focus, redistribute or boost the inductive field strength when heating the remote device  400  in order to increase the spatial freedom for alignment of the remote device  400  and contactless power supply  380 . 
     In another embodiment as shown in  FIG. 75 , the resonant temperature circuit  468  is contained within a food item. As set forth in connection with  FIGS. 32-33  above, the resonant temperature circuit  468  can include a thermocouple, an analog to digital converter connected to the output of the thermocouple, and a variable impedance element connected to the output of the analog to digital converter. In operation, a change in the temperature of the food item can result in a change in the impedance of the resonant temperature sensor circuit  468 . In this embodiment, a wireless power reader coil  480  is operable to detect a change in the reflected impedance of the resonant temperature sensor circuit  468  and identify the corresponding change in temperature of the food item. In some embodiments, the food item can be heated according to the wireless power systems and methods set forth above in connection with  FIGS. 18-33 . In other embodiments, the food item can be heated according to conventional methods. For example, the wireless power reader coil  480  can form part of a microwave oven  482  and/or a stove top  484 , for example a gas range or an electric range. As the food approaches the desired temperature, the wireless power reader coil  480  can provide an output to a controller associated with the microwave and/or stove. In this regard, the microwave or stove controller can shut-off operation of the microwave or stove to prevent overcooking of the food item. Addition, the controller can monitor the output of the resonant temperature sensor circuit  468  to prevent against undercooking the food item. While the resonant temperature sensor circuit  468  is described above as directly monitoring the temperature of the food item, in some applications it can be desirable to indirectly monitor the temperature of the food item. For example, the resonant temperature sensor circuit  468  can also monitor the temperature of the baking pan, frying pan, pot, etc., alone or in combination with the temperature of the food item contained therein. In these and other applications, it can also be desirable to provide microwave shielding to potentially isolate the resonant temperature circuit  468  from microwaves or other electromagnetic radiation that might otherwise interfere with operation of the wireless power reader coil  480 , for example. 
     IV. Portable Device Heater Systems 
     In another aspect of the invention, a system for providing a source of wireless power to a portable heating appliance is illustrated in  FIGS. 34-37  and generally designated  500 . The system generally includes a contactless power supply  510  adapted to provide power to the portable appliance  520  based on its specific power needs. 
     In one embodiment as shown in  FIGS. 34-35 , the contactless power supply  510  is supported by a stowable ironing board  502  to provide power to a cordless clothes iron  520 . The contactless power supply  510  can include one or more primary coils  512  to inductively couple with a secondary coil  522  contained within the cordless iron  520 . The iron  520  can include one or more heating elements  524 ,  526  electrically connected to the output of the secondary coil  522 . A ceramic heating substrate  528  can be positioned between a non-stick surface  530 , for example a Teflon® material by DuPont of Wilmington, Del., and the one or more heating elements  524 ,  526 . The iron  520  can also include a ferromagnetic heating element substantially as set forth in  FIG. 18  above. For example, heating the ferromagnetic material while charging an internal battery can allow that stored energy to later be used with the heating elements  524 ,  526  when the device is removed from the contactless power supply  510 . 
     Operation of the contactless power supply  510  can be understood with reference to  FIGS. 36-37 . The contactless power supply  510  can be used to heat, power, charge batteries and/or read the identifiers and sensors as set forth in Parts I-III above. For example, one method for operating the contactless power supply  510  includes initializing the system at step  540  and driving the first primary coil at step  542 . At step  544 , the contactless power supply  510  can determine whether a cordless iron or other portable device is adjacent the first primary coil  512  substantially as described above in connection with  FIGS. 19-20 . If an iron  510  is present, the power supply  510  can provide power to the first primary coil  512  at step  546 . If at decision step  544  the iron  520  is not present, the power supply  510  can drive the second primary coil  514  at step  548 . If the iron is proximate the second primary coil  514 , the power supply  510  can provide power to the second primary coil  514  at step  550 . If, however, the iron is not present, the power supply  510  samples the next primary coil in the same manner. Accordingly, the contactless power supply  510  can sample each primary coil associated with the ironing board  502  in sequence to provide power to only those primary coils proximate the cordless iron  540 . As also shown in  FIG. 37 , the contactless power supply  510  can first evaluate whether the portable device  520 , or in the present case, an iron, is proximate the contactless power supply. If at step  554  a start button is depressed by a user or the iron  520  is proximate the contactless power supply  510 , the contactless power supply applies power to the desired primary coil  512  to heat the ironing surface of the cordless iron  540 . At decision step  556 , the power supply  510  can determine whether the ironing surface is ready for use (e.g., at the desired temperature) substantially as described above in connection with  FIGS. 28-29 . If the ironing surface is not ready for use, the process repeats itself at step  556 . If, however, the ironing surface is ready for use, a display on either the ironing board  510  or the iron  520  provides a visual or audible indication to a user that the iron is ready for use, as shown in process step  560 . 
     As noted in Part III above, the contactless power supply can provide power to a portable device based on the identity of the portable device and/or based on the state of one or more isolated resonant circuits. To reiterate, in some embodiments the portable device  520  can include a ferromagnetic material  570  that is directly energized by a primary coil  512  of the contactless power supply  510  as shown in  FIG. 38 . In other embodiments, the portable device  520  can alternatively include a heater element  572  electrically connected to the output of a battery  584  which itself is powered by a secondary coil  580  coupled to the primary coil  512  of the contactless power supply  510  as shown in  FIG. 39 . In these embodiments, the contactless power supply  510  indirectly heats a ferromagnetic material  570  to generate heat while simultaneously providing power to a secondary coil  580  within the portable device  520 . The contactless power supply  510  can also read the data back from sensors and selection switches as described above. As shown in  FIG. 40 , the heating element  582  can include all or a portion of an article of footwear such as a boot-insert. When the heating element  582  is placed into the article of footwear  586 , the heating element  582  heats up when proximate a contactless power supply mat  588  to accelerate the drying of the article of footwear  586 . As also shown in  FIGS. 41-43 , the contactless power supply  510  can be utilized to heat hair styling irons  590 . The contactless power supply  510  can be incorporated into a variety of device holding racks  592  to identify and to provide power to the hair styling irons  590  substantially as set forth above. 
     To reiterate, a heating appliance system  500  can include a contactless power supply  510  and a portable heating device  520 . The contactless power supply  510  can include a primary coil  512  and the portable heating device  520  can include a secondary coil  522  electrically connected to a battery. The portable heating device  520  can further include a ferromagnetic heating element  524  and an exposed surface  530 , where the ferromagnetic heating element  524  is electrically connected to the output of the battery. A heating substrate  528  can be positioned between the exposed surface  530  and the heating element  524 , where the contactless power supply heats the ferromagnetic material while simultaneously charging the battery. Energy from the battery can also be utilized to heat the ferromagnetic heating element  524 . The portable heating device  520  can further include a passive identification circuit defining an inductive identification profile and optionally includes the secondary coil  522 . 
     V. Product Alignment Systems 
     According to another aspect of the invention, a product alignment system is illustrated in  FIGS. 44-46  and generally designated  600 . As disclosed below, the product alignment system  600  can improve the coupling coefficient between a primary coil in a display surface and a secondary coil in a product or product package. 
     Referring now to  FIG. 44 , the product alignment system  600  includes a display surface  606  and a plurality of products or product containers  620 ,  622 . The display surface  606  can support multiple rows with each row being defined by an elongate and optionally downwardly sloped supporting member or shelf  608 , laterally spaced, upwardly extending guide rails  610 ,  612 , and a transverse, upwardly-extending lip  614  forward of the lead products  620 ,  622 . Each row can include a spring  616  and a transverse guide plate  618  for advancing the products  620 ,  622  toward a forward portion of the display surface  602  as the lead product is removed from each row  604 ,  606 . Alternatively, or in combination, each product  620 ,  622  can be gravity fed toward a forward portion of the display rack as the lead product is removed, in which instance the spring  616  and guide plate  618  may or may not be provided. 
     As also shown in  FIG. 44 , the display surface  606  includes first and second primary coils  624 ,  626 . The first and second primary coils  624 ,  626  can include horizontally disposed coils each received within a corresponding annular recess in the display surface  606 . Optionally, each primary coil  624 ,  626  is disposed in the forwardmost portion of a row to underlie, and to provide power to, the lead product in each row. In addition, each primary coil  624 ,  626  can include an associated power supply  632  electrically connected to first and second conducting strips  628 ,  630  that extend lengthwise along or within the upwardly-extending lip  614 . A weight activated sensor in the forwardmost portion of each row can detect the presence or absence of a lead product, and thereby activate or otherwise initiate operation of the corresponding power supply. The products  620 ,  622  can each include a secondary coil  634 ,  636 , optionally including a printed trace winding and a printed secondary tank circuit. 
     As each lead product is removed from a corresponding row, the spring  616  and guide plate  618  advance the forwardmost product to a position overlying the primary coils  624 ,  626 , thereby improving the coupling coefficient between the primary coils  624 ,  626  and the secondary coils  634 ,  636 . Optionally, the secondary coil associated with the lead product will consistently or nearly consistently overlie a primary coil in the display surface  606 . In this respect, the product alignment system  600  will advance products to a position that is visible and easily accessible to consumers, while simultaneously providing a source of wireless power to one or more product LEDs, OLEDs, LCD displays, speakers, batteries or other devices associated with the lead product or its packaging. In addition, the product alignment system  600  can ensure each lead product is sufficiently charged prior to purchase, and can assist in the identification, tracking and reordering of such products as set forth above. 
     The present embodiment can be further understood with reference to  FIGS. 45-46 , in which the product alignment system  600  includes first and second parallel display surfaces  640 ,  642  spaced apart from each other. Each display surface  640 ,  642  can include a primary coil at a forward portion of the display surface underlying each lead product. For example, a primary coil can be disposed in the forwardmost portion of the display surface to underlie, and to provide power to, substantially only a lead product, e.g., the forwardmost item or items on the display surfaces. The display surfaces  640 ,  642  can constitute display shelving or end caps common in retail and grocery stores. The display surfaces  640 ,  642  can support multiple items, including products, product containers and/or product displays. For example, the lower display surface  640  can include first and second items  644 ,  646 , and the upper display surface  646  can include third, fourth and fifth items  648 ,  650 ,  652 . Each item can include one or more internal or external energy storage devices, such as a battery or a capacitor. Alternatively, these items can include products not normally associated with an energy storage device. For example, the items can include a collection of differently sized or uniformly sized cereal products. 
     As noted above in connection with  FIG. 46 , each primary coil  624 ,  626  can provide power to a secondary coil  634  associated with the corresponding lead item. The secondary coil  634  can include any circuit adapted to receive wireless power. For example, the secondary coil  634  can include printed tank circuits formed on a flexible, non-conductive substrate including a pressure sensitive adhesive or PSA. As such, the secondary coil  634  can be formed on a low-profile sticker including first and second electrical contacts for connection to the product or product packaging. 
     The product or product packaging  620  can utilize the power transferred to the secondary circuit in any number of ways. For example, the secondary coil  634  can provide power to a load across a rectifying LED, a battery, a speaker circuit, and/or a sequence of LEDs, OLEDs, LCD screens or e-ink displays. Control of the corresponding device, whether it be a battery, LED, speaker, e-ink display, or other device, can be accomplished using multiple isolated resonant circuits in the manner described in Part VI below. Alternatively, control of the corresponding loads can be accomplished with only a single secondary coil in combination with one or more microcontroller-controlled switches to divert power among different loads. 
     Referring again to  FIGS. 45-46 , the power supply  632  can control at least one aspect of a product or product packaging. For example, in a first state, each package, shown as a cereal box, can include an e-ink graphic. In  FIG. 45 , the e-ink graphic is proportionally sized to be coextensive with the forward surface of each cereal box. Thus, the graphic is repeated five times, or once for each leading box of cereal. As shown in  FIG. 46 , however, the e-ink graphic for each box of cereal can change in response to the power supply  632 . For example, the display surface for a cereal box can each include only a portion of the original graphic, such that the entire graphic is proportioned to fit just entirely over the display surface on five boxes of cereal. In addition to resizing, the graphics can animate or illuminate, including the entire graphic or only portions thereof. In this manner, packaging graphics can be changed while the product remains on the display surface, the graphics optionally being uploaded using the contactless power supply. In addition, the e-ink graphics can be used to automatically reconfigure product packaging or signage to correspond to a sale or a season, or can automatically reconfigure product packaging or signage based on any number of other possible factors. The present embodiment is suitable to generate a visual output to promote or otherwise draw attention to a package or packages at the point of sale, optionally in conjunction with the printed speaker circuit, identification circuit, and other embodiments discussed more fully in Part VI below. 
     To reiterate, the product alignment system  600  can include a shelving unit  606  to slideably support a plurality of packages  620 ,  622 , a product pusher  616  supported by the shelving unit and adapted to urge the plurality of packages  620 ,  622  toward a forward portion of the shelving unit  606 , and a primary coil  624  supported by the forward portion of the shelving unit  606  to generate a time varying electromagnetic field. The primary coil  624  can define a central axis generally perpendicular to the shelving unit upper surface. A guide plate  618  can bias the plurality of packages  620 ,  622  toward an upward extending lip  614  in the forward portion of the shelving unit. Each of the packages can also define a base for supporting a secondary coil  624  electrically connected to a load. A corresponding method for controlling a product alignment system can include providing a shelf including a primary coil  624 ,  626 , providing a product supported by the shelf and having a secondary coil connected to a load, aligning the secondary coil to overlie the primary coil, and driving the primary coil with a time varying current to provide a source of wireless power to the load. As noted above, the load can include one of an LED, an e-ink display, an LCD display, an electroluminescent display, an electrostatic speaker or a battery, for example. The method can further include driving the primary coil with an operating frequency that corresponds to the resonant frequency of the secondary coil. 
     VI. Inductive Product and Product Packaging Systems 
     According to another aspect of the invention, a system for providing a source of wireless power to one or more loads associated with product packaging is provided. The system can include a product container having a secondary tank circuit directly or indirectly coupled to one or more visual elements, speaker elements or both. 
     Referring now to  FIG. 47 , the system includes a contactless power supply  700  associated with a display surface to actively respond to a secondary circuit associated with a nearby product and/or product packaging  720 . As explained above in connection with the inductive heating system disclosed in Parts III-IV, the contactless power supply  700  is operable to identify the package  720  and/or its contents through passive inductive communication. Upon identification and authentication, the contactless power supply  700  can provide power to the package  720  according to a predetermined profile. Alternatively, upon identification and authentication, the contactless power supply  700  can switch from a passive communications mode to an active communications mode where it provides power according to a data signal sent by the secondary circuit within the product or product container  720 . Where described in connection with a product, the present invention can also be utilized in connection with its packaging. Similarly, where described below in connection with packaging, the present invention can be utilized in connection with the product itself. 
     Referring again to  FIG. 47 , the contactless power supply  700  includes a power supply  702 , an inverter  704  electrically coupled to the output of the power supply  702 , and a tank circuit including a series capacitor  706  and primary coil  708 . In addition, a controller  710  is electrically connected to a mains input, the power supply  702 , the inverter  704 , and tank circuit for controlling a characteristic of the power applied to the primary coil  708 . In one embodiment, the controller  710  selectively controls the frequency at which power is generated in the primary coil  708 . In other embodiments, the controller selectively controls the phase, amplitude, duty cycle, pulse width and/or other characteristic of the time-varying current in the primary coil. In operation, the contactless power supply  700  applies power to the primary coil  708  at an identification frequency and then evaluates the reflected impedance in the primary tank circuit using a current sensor or a voltage sensor, for example. If the product container  720  has a resonant frequency at the operating frequency, the contactless power supply  700  can recover operating parameters from memory to provide power to the product container  720  according to a predetermined profile. In addition, the contactless power supply  700  can optionally include an isolated re-resonator coil  712  that acts to shape, focus, redistribute or boost the inductive field strength when inductively coupled with the product container  720  in order to increase the spatial freedom for alignment of the product container  720  and the contactless power supply  700 . 
     As also shown in  FIG. 47 , the product container  720  includes three isolated resonant circuits  722 ,  724 ,  726 . As described above, the contactless power supply  700  determines the identity of the product container  720  by sweeping through a predetermined range of operating frequencies while monitoring the current in the primary coil  708 . When the current in the primary coil  708  passes a threshold value, or achieves a local maxima or other criteria, the controller  710  is able to record the frequency at which the event occurred. By sweeping through a range of frequencies, the contactless power supply  702  is able to determine and record the resonant frequencies of each of the isolated resonant circuits  722 ,  724 ,  726 . The presence or absence of a resonant frequency may be considered data bits. The controller  710  is then able to translate those frequencies into a unique device or package identification code. The identification code may be binary or a series of selections within the predefined resonant identifier placeholders. The contactless power supply  700  then utilizes the identification code to provide power to the container  720  according to the specific needs of the container  720  and the contents therein. For example, power applied by the contactless power supply  700  can be utilized to illuminate one or more LEDs, LCD displays, or e-ink displays on the product or package exterior, in which case a fixed power output can be applied. A microprocessor for controlling the display, sound and other functions may also be included in the packaging. Alternatively, power applied by the contactless power supply  700  can be utilized to charge a rechargeable battery or capacitor contained within the product. In this case, the contactless power supply  700  can provide a variable amount of power based on the resonant frequency or the reflected impedance of a secondary circuit associated with the product or product package  720 . In this example, power is used to top-off the rechargeable battery prior to removal of the item from the point of sale display. In still another example, the point of sale display may include a package containing an electronic device such as a music player or a hand-held global position system device. These types of devices can be recharged according to specific power needs and can receive data from the contactless power supply  700 . For example, the latest operating system can be inductively uploaded to the device while still within its packing or on the point of sale display. Alternatively, the contactless power supply  700  can upload other forms of media, including songs, photos, games, videos or maps. 
     In another embodiment as shown in  FIG. 48 , the product or product packaging  720  includes three isolated resonant circuits  722 ,  724 ,  726 , a secondary tank circuit  730  and an active electronics load  728 . In this embodiment, the contactless power supply  700  identifies the product according to the reflected impedance of the isolated resonant circuits  722 ,  724 ,  726  substantially as described above in connection with  FIG. 47 . The contactless power supply  700  then uses the corresponding identification code to provide power to the active electronic load  728  in the product or product package  720  at rates appropriate for the product or product package  720 . As alternatively shown in  FIG. 49 , the product or product packaging  720  includes a sensor circuit  732 . In this embodiment, the sensor circuit  732  includes a secondary coil  734 , a series capacitor  736 , and a sensor  738  including a variable impedance element. In operation, a variation in the sensor output results in a change in the impedance of the sensor circuit  732 . The contactless power supply  700  is operable to detect a change in the reflected impedance of the sensor circuit  732 , and is further operable to adjust the power output. As also shown in  FIG. 49 , the contactless power supply  700  can include an isolated re-resonator circuit  712 , for example an LC circuit, that acts to shape, focus, redistribute or boost the inductive field strength when inductively coupled with the package  720  in order to increase the spatial freedom for alignment of the package  720  and contactless power supply  700 . 
     In another embodiment, the product or product container can include a printed speaker circuit  750  including a low-profile electrostatic speaker drivable by the contactless power supply  700 . Referring now to  FIG. 50 , the printed speaker circuit  750  includes a secondary tank circuit  752  and an electrostatic speaker  754  electrically connected to the secondary tank circuit  752 . The secondary tank circuit  752  includes an inductive element  756  and a series resonant capacitor  758 . The inductive element  756  can include printed trace winding, and the series resonant capacitor  758  can be selected such that the secondary tank circuit  752  includes a resonant frequency corresponding to the driving or operating frequency of a contactless power supply  700 . The secondary tank circuit  750  can be formed on a flexible, non-conducting substrate applied to an exterior surface of a product  720 , optionally using a pressure sensitive adhesive. The secondary tank circuit  752  can further include first and second electrical contacts  760 ,  762 , optionally in direct electrical contact with portions of the electrostatic speaker  754 . 
     The electrostatic speaker  754  includes a supportive conductive plate  764 , a thin conductive membrane  766  spaced apart from the supportive conductive plate  764 , and an insulator  768  disposed therebetween. The supportive conductive plate  764  is an electrically conductive stationary member connectable to the first electrical contact  760  of the secondary tank circuit  752 . The thin conductive membrane  766  is a flexible membrane having a conductive coating suitable to hold an electrostatic charge. The thin conductive membrane  766  is electrically connected to a second electrical contact  762  of the secondary tank circuit  752 . As also shown in  FIG. 50 , the insulator  768  separates the supportive conductive plate  764  from the spaced apart conductive membrane  766 , and is coextensive with the supportive conductive plate  764 . 
     In operation, a contactless power supply induces a frequency and/or amplitude modulated waveform in the secondary tank circuit  752  to drive the electrostatic speaker  754 . The waveform, applied across the first and second electrical contacts  760 ,  762  as a time varying voltage, drives the supportive conductive plate  764 , which variably attracts or repels the charged membrane  766 , causing the membrane  766  to move toward or away from the supportive conductive plate  764 . Movement of the conductive membrane  766  generates a sound according to the frequency and/or amplitude modulated waveform. Optionally, the speaker can include a second supportive conductive plate spaced apart from the thin conductive membrane  766  opposite the first supportive conductive plate  764  and electrically coupled to the second electrical contact  762 . In addition, an energy storage device such as a battery or a capacitor can be electrically connected between the secondary tank circuit  752  and the speaker  754 , the battery or capacitor being operable to power a drive circuit (not shown) for the speaker  754 . 
     In use, the speaker circuit  754  can be positioned in any location on or within a corresponding package suitable to receive wireless power from a contactless power supply. The contactless power supply can be associated with a point of sale display substantially as described in Part V above. In this example, the contactless power supply induces the AC audio signal in the secondary tank circuit  752  when the package  720  is at the forwardmost portion of the display. As a result, the speaker  752  generates an audible output to promote or otherwise draw attention to the package  720  at the point of sale. 
     In another embodiment, the product or product container  720  can include a multi-coil, multi-frequency tuned circuit as shown in  FIGS. 51-52  and generally designated  770 . The tuned circuit  770  includes multiple printed circuits each being tuned to resonate at a corresponding operating frequency. The tuned circuit  770  can be used to illuminate a sequence of LEDs associated with a product, product packaging or a point of sale display. 
     Referring now to  FIG. 51 , the three-coil three-frequency tuned circuit  770  includes first, second and third printed circuits  772 ,  774 ,  776 . Each printed circuit includes an inductive element  778 , a series resonant capacitor  780 , an LED  782  and a series resistive load  784 . The inductive element  778  can include a printed trace winding or windings substantially as described above. The series resonant capacitor  780  can be selected such that each printed circuit  772 ,  774 ,  776  includes a resonant frequency corresponding to a driving or operating frequency of a contactless power supply. The resonant frequency of each printed circuit can differ from each other, for example, to allow sequential illumination of each LED  782  as the contactless power supply operating frequency varies. Though described as including an LED, each printed circuit can alternatively include an electroluminescent display, an e-ink display, an LCD display  786 , or any other suitable display. The three-coil three-frequency tuned circuit  770  can be formed on a flexible, non-conducting substrate applied to an exterior surface of a product using an adherent, for example a pressure sensitive adhesive. 
       FIG. 53  includes a flow chart illustrating the operation of a contactless power supply  700  in connection with the multi-coil multi-frequency tuned circuit  770  of  FIGS. 51-52 . The sequence commences at step  790 , and at step  792  the contactless power supply  700  drives a primary tank circuit at a first operating frequency and for a first duration. At step  794 , the contactless power supply drives the primary tank circuit at a second operating frequency and for a second duration. At step  796 , the contactless power supply drives the primary tank circuit at a third operating frequency and for a third duration. It should be noted that while the respective first, second and third operating frequencies will normally differ from one another, the first, second and third durations may remain substantially identical to each other (represented in  FIG. 53  as “x”). In addition, the first, second and third operating frequencies will normally correspond to the resonant frequencies of the first, second and third printed circuits  772 ,  774 ,  776 . At the respective resonant frequencies, the corresponding LED will illuminate in response to a resulting increase in power transfer between the contactless power supply and the corresponding printed circuit  772 ,  774 ,  776 . 
     Returning again to  FIG. 53 , at decision step  798  the contactless power supply determines whether motion is detected proximate the product, optionally using passive infrared motion sensors or other suitable device. If at step  798  motion is detected, the sequence proceeds to step  800  and a timer is reset, and steps  790 ,  792 ,  794  and  796  are repeated. If, however, at step  798  motion is not detected, the contactless power supply determines at step  802  if the timer has expired. If the timer has not expired, the contactless power supply repeats steps  792 ,  794  and  796  to illuminate the first, second and third LEDs. If, however, the timer has in fact expired and no further motion is detected, the contactless power supply will enter a standby mode at step  804  and monitor for motion at step  806 . If motion is detected at step  806 , the sequence will repeat itself at step  790 . 
     While the multi-coil multi-frequency tuned circuit is described above as relating to LEDs, the multi-coil multi-frequency tuned circuit can alternatively relate to LCDs, electroluminescent display, e-ink displays or other suitable displays. In addition, the inherent resistance of each inductive element  778  can eliminate the need for a resister in the printed circuit  772 ,  774 ,  776 , while the selection or tuning of the inductive element can likewise eliminate the need for a tuning capacitor  780 . At the point of sale, the LEDs generate a visual output to promote or otherwise draw attention to a package or packages, optionally in conjunction with the printed speaker circuit or other embodiments as disclosed herein. 
     In another embodiment as shown in  FIG. 54 , the product container  720  includes a cap or lid  810 , wherein removal of the cap or lid  810  is detected by a contactless power supply  700  positioned within a display surface. In this embodiment, the product container  720  includes a series resonant circuit formed of conductive ink on a non-conducting substrate  812 , where the substrate extends across a portion of the cap or lid  810  and a portion of the product container  720 . The series resonant circuit includes a resistive element and a switch, where the switch is operable to short the resistive element when closed. The cap or lid  810 , once removed from the product container  720 , opens the switch. The resulting change in impedance of the series resonant circuit is detected by the contactless power supply  700  to indicate removal of the cap or lid from the product container  720 . In addition, multiple series resonant circuits may be combined in a single product container  720 . For example, product container  720  can include first and second pressure sensors  814 ,  816  in addition to the perforated tab as described above. In this example as shown in  FIG. 54 , a first pressure sensor  814  is located at the base of the product container  720  to indicate depletion of the product container contents, and a second pressure sensor  816  is located on the surface of the product container  720  in a location that is intended to be gripped by a user. Actuation of the pressure sensors  814 ,  816  operate to vary the impedance of one or more series resonant circuits, which is detected by the contactless power supply  700  substantially as set forth above. 
     In another embodiment as shown in  FIGS. 55-57 , the product container  720  contains a paperboard tab  820  including first and second conductive contacts  822 ,  824  and a secondary coil  826  whose output is conditioned before being provided to the first and second conductive contacts  822 ,  824 . As shown in  FIGS. 56-57 , the conductive contacts  822 ,  824  can be arranged within a battery container  828  such that a rechargeable battery can be positioned between the first and second conductive contacts  822 ,  824 . In this respect, the contactless power supply  700  is operable to recharge a battery contained within a product or product packaging  720  prior to its removal from the point of sale display. As shown in  FIGS. 56-57 , the product container  720  can include a pressure sensitive switch  832  within an over-label  834  which actuates a battery test circuit when pressed. An LED  832  or other suitable low-power visual, audible, or haptic feedback element may be employed to indicate the battery charge status when the pressure switch  832  is depressed. Once the over-label  834  is depressed by a user, a conductive trace  838  printed on the underside of the over-label  834  closes the battery test circuit, which then illuminates the LED  830  on the package exterior. Accordingly, the point of sale display system provides power to recharge the battery contained within a product or product container, and also provides a visual indication to the user of the charge status of the corresponding internal battery. 
     Another embodiment of the contactless power supply  700  for supplying power to a product or product container  720  is shown in  FIG. 58 . The contactless power supply  700  may include a power supply  840 , inverter  842 , inverter driver  844 , sensors  846 , and controller  848 . Further, the inverter  842  and sensors  846  may be connected to a resonant capacitor  850  and a primary coil connector  852 . The primary coil connector  852  may be connected to a primary coil (not shown). The resonant capacitor  850  and primary coil may form a tank circuit similar to the resonant capacitor  706  and primary coil  708  described above with regard to  FIG. 47 . The inverter  842  may provide an output signal for driving the resonant capacitor  850  and primary coil for inductively coupling with a remote device, and the inverter driver  844  may include circuitry for providing an interface between the controller  848  and the inverter  842 . Accordingly, through the inverter driver  844 , the controller  848  may control the output of the inverter  842  and parameters of the inductive coupling with the remote device. The controller  848  may include a processor and related interface circuitry for receiving sensor information from the sensors  846  and controlling the inverter  842 . The controller  848  may control the output of the inverter  842  based on the sensor information received from the sensors  846 . In some embodiments, the controller  848  may also interface with external components using a connector to transmit information or send control signals. In the current embodiment, the sensors  846  may include current sensor circuitry and voltage sensor circuitry for measuring characteristics of the inverter  842  output, resonant capacitor  850 , and primary coil  852 . For example, the sensors  846  may measure the current through the primary coil  852 . In another example, the sensors  846  may indicate the phase difference between (1) the voltage output from the inverter  842  and (2) the voltage between the resonant capacitor  850  and the primary coil  852 . The power supply  840  of the current embodiment may receive power from the mains input  854  and supply power to the contactless power supply  700 . The controller  848 , inverter driver  844 , inverter  842 , and sensors  846  may each receive suitable power from the power supply  840 . For example, the controller  848  may receive substantially 5 VDC and the inverter  842  may receive another voltage for transferring power to a remote device. An additional example of a low voltage distribution system is disclosed in U.S. application Ser. No. 12/791,560, entitled “Wireless Power Distribution and Control System” filed Jun. 1, 2010 by Baarman, now U.S. Pat. No. 8,618,770, the disclosure of which is incorporated by reference in its entirety. 
     In the above embodiments, the electronic circuitry may be constructed on printed circuit board material using discrete components or chips. Alternatively, the circuitry may be constructed from conductive ink printed on a paper, plastic or other suitable substrate. In addition, resistive, capacitive and inductive components may also be printed on the substrate so that conventional discrete components are reduced or entirely eliminated from the circuit. 
     VII. Product and Product Package Identification 
     According to a seventh aspect of the invention, systems and methods for the wireless identifications of one or more products are provided. 
     In one embodiment, a multi-winding shielded identification circuit is illustrated in  FIG. 59  and generally designated  900 . As disclosed below, the multi-winding shielded identification circuit  900  is operable to identify and/or authenticate a product or product container when used in combination with a contactless power supply optionally associated with a point of sale display. Upon identification and authentication, the contactless power supply can provide power to the product or product container according to a predetermined profile. Alternatively, the contactless power supply can switch from a passive communications mode to an active communications mode where it provides power according to a data signal sent by the multi-winding shielded identification circuit  900 . 
     Referring now to  FIG. 59 , the multi-winding shielded identification circuit  900  includes first, second and third identification windings  902 ,  904 ,  906  and corresponding first, second and third printed shielding  908 ,  910 ,  912 . The identification windings  902 ,  904 ,  906  can be generally co-planar and formed on a non-conducting substrate in side-by-side orientation. Alternatively, the windings  902 ,  904 ,  906  can be formed on a non-conductive substrate in overlapping alignment. In the above orientations, the first printed shielding  908  partially encompasses the first printed or trace winding  902 , and the second and third printed shieldings  910 ,  912  partially encompass the second and third trace windings  904 ,  906 , respectively. The printed shieldings  908 ,  910 ,  912  vary in at least one characteristic among each other. For example, the first printed shielding  908  can encompass a first surface area of the first trace winding  902 , the second printed shielding  910  can encompass a second surface area of the second trace winding  904 , and the third printed shielding  912  can encompass a third surface area of the third trace winding  906 , where the first, second and third surface areas are successively smaller. In this regard, each winding and shielding combination  914 ,  916 ,  918  will generate a distinct reflected impedance when subject to a given magnetic flux, particularly where the windings, shieldings and coupling coefficients are otherwise identical. In other words, each printed shielding  908 ,  910 ,  912  limits the electromagnetic exposure of the corresponding windings  902 ,  904 ,  906  to varying degrees, thereby bringing out the individual response in each pairing. The printed shielding layers  908 ,  910 ,  912  can optionally be formed of any suitable material, including for example an ELECTRODAG® dielectric ink by Henkel Corporation of Irving, Calif. The printed shielding layers can create a limited field exposure window for each corresponding winding  902 ,  904 ,  906  to effectively decouple each winding  902 ,  904 ,  906 . As a result, the printed shielding layers can enhance identification patter of each of winding, even among secondary windings having similar or identical resonant frequencies. 
     As noted above, the multi-winding shielded identification circuit  900  can be used in combination with a contactless power supply to identify and/or authenticate a corresponding product or product package. For example, the contactless power supply can determine the identity of the product or product container by sweeping through a predetermined range of frequencies while monitoring the reflected impedance of the multi-winding shielded identification circuit  900 . That is, the isolated winding-shielding pairings  914 ,  916 ,  918  in the identification circuit  900  react differently to the contactless power supply depending on the operating or driving frequency of the contactless power supply primary tank circuit. As a result, the isolated winding-shielding pairings can cause variations in the current or voltage in the primary tank circuit across the range of operating frequencies. For example, the isolated winding-shielding pairings can cause variations in the peak voltage or current through the primary tank circuit. When the voltage or current in the primary tank circuit passes a threshold value, a controller in the contactless power supply is able to record the frequency at which the event occurred. By sweeping through a range of frequencies, the contactless power supply is able to determine and record the resonant frequencies of each of the isolated winding-shielding pairings. The controller can then translate those frequencies into a unique device or package identification code. The contactless power supply can utilize the identification code associated with the multi-winding shielded identification circuit  900  to provide power to the product and/or product package according to the specific needs of the product and/or product package. For example, power applied by a contactless power supply can be utilized to illuminate one or more LEDs, LCD displays, or e-ink displays on the product or package exterior, in which case a fixed power output can be applied. A microprocessor for controlling the display, sound and other functions may also be included in the product packaging. Alternatively, power applied by a contactless power supply can be utilized to charge a rechargeable battery or capacitor contained within the product. In this case, the contactless power supply can provide a variable amount of power based on the reflected impedance of the multi-winding shielded identification circuit  900  associated with the product or product package. In this example, power is used to top-off the rechargeable battery prior to removal of the item from the point of sale display. 
     In another embodiment, a method for generating a unique identification code based on the reflected impedance of a passive identification circuit is provided. A suitable identification circuit can include any circuit having two or more resonant frequencies. For example, a suitable identification circuit can include the multi-winding shielded identification circuit  900 . Alternatively, a suitable identification circuit can include any of the identification circuits disclosed in Parts I-VI and VIII. 
     In the identification and authentication of a product or product container, an inductive reader  102  can sweep through a range of operating frequencies. That is, an inductive reader  102  can drive a primary tank circuit at a plurality of operating frequencies while monitoring the primary tank circuit voltage, current and/or phase. For example, an inductive reader can sweep through a range of frequencies from 120 kHz to 300 kHz while monitoring the primary tank circuit voltage, current and/or phase to identify a resonant frequency of the identification circuit. This frequency range of 180 kHz can be broken into n equally spaced intervals, where n is dependent on how accurately the identification circuit is tuned. For example, n can be equal 3 to indicate three 60 kHz intervals or “bins” between 120 kHz and 300 kHz. 
     In the present example, each bin is represented by a binary value corresponding to the presence or absence of a resonant frequency. The resonant frequency can correspond to current or voltage in excess of a threshold value, a local current or voltage maxima or other criteria. When the inductive reader  102  identifies a resonant frequency in a given bin, the bin is represented in binary terms by a 1. When the inductive reader  102  does not identify a resonant frequency in a given bin, the bin is represented in binary terms by a 0. For an identification circuit having k number of isolated resonant circuits (and at least k number of resonant frequencies), the number of possible identification codes is represented by the following formula: 
               n   !           (     n   -   k     )     !     ⁢     k   !             
In this example, the identification circuit includes two isolated resonant circuits (k=2) each having a resonant frequency in one of three bins between 120 kHz and 300 kHz (n=3). According to the above formula, there are three possible identification codes: 110 (bins 1 and 2), 101 (bins 1 and 3), and 011 (bins 2 and 3). This assumes no bin will be occupied by two isolated resonant circuits, and that each isolated resonant circuit will occupy at least one bin.
 
     In order to maximize the number of possible identification codes, each bin can be assigned a prime number according to Table 3 below. The x-axis values (2, 3, 5, . . . n) represent a prime number and the y-axis values (1, 2, 3, . . . m) represent a bin: 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Identification Code Key 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 2 
                 3 
                 5 
                 7 
                 11 
                 13 
                 17 
                 19 
                 . . . 
                 n th  prime 
               
               
                   
               
               
                 1 
                 2 1   
                 3 1   
                 5 1   
                 7 1   
                 11 1   
                 13 1   
                 17 1   
                 19 1   
                   
                 n 1   
               
               
                 2 
                 2 2   
                 3 2   
                 5 2   
                 7 2   
                 11 2   
                 13 2   
                 17 2   
                 19 2   
                   
                 n 2   
               
               
                 3 
                 2 3   
                 3 3   
                 5 3   
                 7 3   
                 11 3   
                 13 3   
                 17 3   
                 19 3   
                   
                 n 3   
               
               
                 4 
                 2 4   
                 3 4   
                 5 4   
                 7 4   
                 11 4   
                 13 4   
                 17 4   
                 19 4   
                   
                 n 4   
               
               
                 5 
                 2 5   
                 3 5   
                 5 5   
                 7 5   
                 11 5   
                 13 5   
                 17 5   
                 19 5   
                   
                 n 5   
               
               
                 6 
                 2 6   
                 3 6   
                 5 6   
                 7 6   
                 11 6   
                 13 6   
                 17 6   
                 19 6   
                   
                 n 6   
               
               
                 7 
                 2 7   
                 3 7   
                 5 7   
                 7 7   
                 11 7   
                 13 7   
                 17 7   
                 19 7   
                   
                 n 7   
               
               
                 8 
                 2 8   
                 3 8   
                 5 8   
                 7 8   
                 11 8   
                 13 8   
                 17 8   
                 19 8   
                   
                 n 8   
               
               
                 9 
                 2 9   
                 3 9   
                 5 9   
                 7 9   
                 11 9   
                 13 9   
                 17 9   
                 19 9   
                   
                 n 9   
               
               
                 10  
                     2 10   
                     3 10   
                     5 10   
                     7 10   
                     11 10   
                     13 10   
                     17 10   
                     19 10   
                 
                     
                 
                 n 10   
               
               
                 . . . 
               
               
                 m th  row 
                     2 m   
                     3 m   
                     5 m   
                     7 m   
                     11 m   
                     13 m   
                     17 m   
                     19 m   
                 
                     
                 
                 n m   
               
               
                   
               
            
           
         
       
     
     If bins 1 and 2 were determined to be filled as disclosed above, and for a key of 3-11-5, the product of each prime number raised to the corresponding bin integer is: 3 1 ×11 2 ×5 0 =363, where 363 represents the unique identifier. No other combination produces this numeric identifier because 363 has one unique prime factorization. This unique identifier can now be assigned as an identification number for a specific product. If however bins 1 and 3 were determined to be filled, and for the same key, the product of each prime number raised to the corresponding bin is: 3 1 ×11 0 ×5 3 =375, where 375 represents the unique identifier. 
     The unique identifier can be decomposed into the corresponding bins (a, b, c) with prior knowledge of the key (3-11-5) by the following formula: unique identifier=3 a ×11 b ×5 c . In particular, by running through each keyed prime number assigned to m bins, the numeric identification codes 363 and 375 can be factored down to each corresponding prime factorization. As a result, one can deduce or “back out” those identification circuit bins that are filled. In addition, an additional key can be assigned to an passive identification circuit  116  having the same filled bins, thus increasing the number of available identifiers. For example, a passive identification circuit  116  filling bins 1 and 2 can achieve a unique identifier of 640 with a key of 5-7-3 or a unique identifier of 44 with a key of 11-2-3. A controller  112  associated with an inductive reader  102  can then assign the unique identifier to the corresponding product and communicate the unique identifier—and optionally other information related to the product—to a central hub  168  as set forth above. 
     Where each isolated resonant circuit occupies only one bin, the equation for all possible numeric identification codes becomes: 
               ∑     i   =   1     k     ⁢         n   !           (     n   -   i     )     !     ⁢     i   !         ·     m   i             
where n represents the number of possible prime numbers, k represents the number of isolated resonant circuits, and m represents the number of possible bins.
 
     Where each isolated resonant circuit occupies more than one bin, the below five operations provide solutions for k=1 through 5, respectively: 
     
       
         
           
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                   ⁢ 
                   
                     2 
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               · 
               
                 m 
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               m 
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               n 
             
           
         
       
       
         
           
             
               
                 
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     Based on the above operations, a significant number of possible combinations can be generated with a given number of bins, isolated resonant circuits, and powers of primes. For example, for an identification circuit having only two coils for five bins, there are 4,100 possible numeric combinations where n=20. The possible numeric combinations increases to 9,150 for n=30, 25,250 for n=40 and 100,500 for n=100. Also by example, with five coils (k=5), thirty bins (m=30) and thirty prime numbers (n=30), there can be 3,552,347,286,900 possible unique product identifiers. While described as relating to numeric identification codes for products and product packaging, the method of the present embodiment can be utilized across a wide range of other applications where remote device identification by inductive coupling is desired. 
     To reiterate, a product identification system can include a storage device  104  for a product including a plurality of isolated resonant circuits  120 ,  122  and an inductive reader  102  including a primary tank circuit, the inductive reader  102  being adapted to determine the identity of the product based on the resonant frequencies of the isolated resonant circuits  120 ,  122 . The inductive reader  102  can include a controller  112  adapted to assign a prime number and an integer to the resonant frequency of each of the plurality of isolated resonant circuits  120 ,  122 . The controller  112 , or central hub  168  for example, can then assign a unique identifier to the storage device  104  based on the product of the prime number raised to the corresponding integer for each resonant frequency, where the unique identifier defines a prime factorization. For example, a plurality of isolated resonant circuits having resonant frequencies of 130 kHz (bin 1) and 200 kHz (bin 2) can have a unique identifier of (or based on) 363 according to the formula 3 1 ×11 2 ×5 0  for a key of 3-11-5. 
     In another embodiment, a device identification system is illustrated in  FIG. 60  and generally designated  920 . As disclosed below, the device identification system  920  can be used to share data between portable devices, contactless power supplies, and products or product packages. Referring now to  FIG. 60 , the device identification system includes a contactless power supply  922 , a portable device  924  and one or more packages  926 ,  928 . The contactless power supply  922  can include a series or parallel resonant capacitor and a controller for storing a plurality of identification profiles. The first package  926  can include a secondary tank circuit including a secondary coil  930 . The secondary coil  930  can include a printed trace winding on a flexible, non-conductive substrate, which can be applied to an exterior surface of the package  926  using an adherent. The first package  926  can also include a series or parallel resonant capacitor selected to have a capacitance such that the secondary tank circuit includes a resonant frequency corresponding to a driving or operating frequency of the contactless power supply  922 . 
     In use, the contactless power supply  922  can provide power to the first package  926 , and can identify and authenticate the first package substantially as described above. In this regard, the contactless power supply  922  and the first package  926  include a wireless power and passive communication link. In like manner, the portable device  924  and a second package  928  also share a passive communication link, where the mobile device  924  is optionally operable to provide wireless power to the second package  928 . In this embodiment, the portable device  924 , optionally a mobile device such as a mobile phone or personal digital assistant (PDA), includes a contactless power supply having a primary coil  934 . The second package  928  includes a corresponding secondary coil  936 . The primary and secondary coils  934 ,  936  can include printed windings on a flexible, non-conductive substrate, optionally applied to the exterior of the device  924  and package  928  using an adherent. In a communications-only mode, the device  924  can identify and authenticate the package  928  in the manner described above in connection with the contactless power supply  922  and first package  926 . In a communications and power mode, the device  924  can provide wireless power to the package  928  according to a predetermined profile in response to the identification and authentication of the package  928 . 
     The portable device  924  can receive data unrelated to the identity or power needs of the package  928 . For example, the portable device  924  can receive one or more virtual codes associated with the package  928 , and can electronically verify the code and/or determine if the code is a winner. In this example, the code can correspond to the reflected impedance of the secondary coil  936  when closely coupled with the primary coil  934  of the portable device  924 . Using an internet connection, for example, the device  924  can verify the status of the code, or redeem the code, at a host website, optionally as part of a promotional sweepstakes for the package  928 . In this regard, additional information is shared between the device  924  and the package  928  that may not be part of the package identification or other information associated with wireless power transfer. 
     In another embodiment, a point of sale wireless power system is illustrated in  FIGS. 61-63  and generally designated  940 . As disclosed below, the wireless power system  940  can be used to share power and data between a contactless power supply, products and/or product packages associated with a point of sale display. 
     Referring now to  FIG. 61 , the point of sale wireless power system  940  includes a first contactless power supply  942 , a first container or package  944  and a first product  946  contained within, supported by or otherwise associated with the first package  944 . The first contactless power supply  942  can include a primary tank circuit  948  and a controller  950  for storing a plurality of identification profiles, power transfer profiles, or other information. The corresponding product  946  can include a secondary tank circuit  952  contained on or within the product itself. The secondary tank circuit  952  can provide power to an internal battery contained within the product  946  to ensure the battery is sufficiently charged prior to purchase. Alternatively, or in addition, the secondary tank circuit  952  can provide power to a load associated with the product  946 . For example, the load can include one or more LEDs, OLEDs, LCD displays, e-ink displays, speaker circuits, servos, transducers, actuators, motors, or other devices. In addition, the product  946  can include a demo mode, by which the product  946  generates sound, motion, animation or illumination to attract attention to the product  946 , particularly when subject to a time varying electromagnetic field from the primary tank circuit  948 . This can be desirable where all or a portion of the product  946  is visible through the product container  944 . 
     As also shown in  FIG. 61 , the system  940  can include a second contactless power supply  954  underlying or proximate to a second product  956  contained within a second package  958 . Like the first contactless power supply  942 , the second contactless power supply  954  includes a primary tank circuit  960 . Though not shown, the primary tank circuit  960  can include a series or parallel resonant capacitor, and the second contactless power supply  954  can include a controller for storing a plurality of identification profiles, power transfer profiles, or other information. The corresponding product  956  includes a secondary tank circuit  962  contained within the product itself to power to an internal battery and/or to directly power the product  956 . In addition, the packaging  958  can include an additional secondary tank circuit  964  to provide power to a load  966 . The load can include an LCD, OLED, LED, e-ink display, speaker or other device substantially as described above. The product  956  and the package  958  can each generate sound, motion, animation, illumination or other output. In this respect, the product  956  interacts with the packaging lighting, for example, and other functions to promote the product  956  at the point of sale. As optionally shown in  FIG. 62 , the second package  958  can further include a heating element  968 . The heating element  296  can include a ferromagnetic material substantially as described above in connection with  FIG. 18 . For example, the heating element  968  can include a metal foil applied to a paperboard surface of the second package  958  to heat the package contents at the point of sale. The heating element  968  can be directly heated by application of a magnetic flux from the primary tank circuit  960 , or can be indirectly heated using a secondary tank circuit and optional battery. The package contents can include a heated beverage, food product, lotion, serum and/or therapy ointment, for example. 
     Referring now to  FIG. 63 , the point of sale wireless power system  940  can include a printed label  970  for a package  972  at the point of sale. The printed label  970  includes a secondary coil  974  electrically connected to a load. The secondary coil  974  can include a printed trace winding, and the load can include an LCD, OLED, LED, e-ink display, speaker or other device substantially as set forth above. The load and the secondary coil  974  can be formed on a flexible, non-conductive substrate having an adhesive backing. The substrate includes a fold line  978 , for example a weakened or perforated hinge, separating an upper portion of the substrate  980  from a lower portion of the substrate  982 . The upper portion of the substrate  980  supports the load, and the lower portion of the substrate  982  supports the secondary coil  974 . The label  970  can be sized to generally conform to at least one surface of the package  972 . For example, the upper label portion  980  can be sized to conform to at least one sidewall of the package  972 , while the lower label portion  982  can flex about the fold line  978  to conform to the base of the package  982 . As noted above, the label  970  can include an adherent, for example a pressure sensitive adhesive, on a rear surface thereof to join the label  970  to the package  972 . In use, the secondary coil  974  is placed proximate a corresponding primary coil to improve the coupling coefficient therebetween. 
     VIII. Printed Secondary Circuits 
     According to another aspect of the invention, a printed ink secondary circuit is illustrated in  FIG. 64  and generally designated  1100 . As disclosed below, the printed ink secondary circuit  1100  can increase the range of a contactless power supply used in connection with a point of sale display. In particular, the printed ink secondary circuit  1100  can increase the range of a wireless power system by electrically isolating a resistive load from the secondary coil of a contactless power supply. 
     Referring now to  FIG. 64 , the printed ink secondary  1100  is formed on a non-conductive flexible substrate and includes a receiver primary trace winding  1122  and a receiver secondary trace winding  1124 . The receiver primary trace winding  1122  and the receiver secondary trace winding  1124  are substantially coplanar and coaxial, where the receiver primary trace winding  1122  encompasses and is radially spaced apart from the receiver secondary trace winding  1124 . The receiver primary trace winding  1122 —which functions as the inductive secondary in a contactless power supply system—is shown as including an inductive element  1126  with three windings and an optional resistive, capacitive, or conductive element  1128  extending across first and second end portions  1130 ,  1132  of the inductive element  1126 . The resistive, capacitive or conductive element  1128 , optionally referred to as a printed ink jumper  1128 , is spaced apart from the inductive element  26  using a first printed ink insulated layer  1134 . The printed ink jumper  1128  can be selected to improve the overall performance and efficiency of the printed ink secondary  1120 , and in particular the receiver primary trace winding  1122 . For example, the printed ink jumper  1128  can include a capacitive element selected such that the receiver primary trace winding  1122  includes a resonant frequency corresponding to the driving or operating frequency of an primary coil/contactless power supply. In this respect, the printed ink jumper  1128  can be selected to tune or otherwise optimize the performance of the printed ink secondary  1120 . 
     As also shown in  FIG. 64 , the receiver secondary trace winding  1124  includes an inductive element  1136  with four windings, the inductive element  1136  being substantially disposed within the core of the receiver primary trace winding  1122 . The receiver secondary trace winding  24  further includes first and second end portions  1138 ,  1140  extending over and spaced apart from the primary inductive element  1126 . In addition, second and third printed ink insulating layers  1142 ,  1144  are interposed between the first and second end portions  1138 ,  1140 , respectively, and the primary inductive element  1126 . The first and second end portions  1138 ,  1140  of the receiver secondary trace winding  1124  can be electrically coupled across a load (not shown) to provide a source of electrical power to the load. Although the receiver primary and secondary trace windings  1122 ,  1124  are shown in  FIG. 64  on the same side of the non-conductive flexible substrate, the receiver primary and secondary trace windings  1122 ,  1124  may alternatively be disposed on opposite sides of the non-conductive flexible substrate. In addition, the receiver primary and secondary trace windings  1122 ,  1124  may include any suitable geometry as desired, including spiral, rectangular or jagged windings, and may include any number of windings as desired. 
     As noted above, the printed ink secondary  1120  can be utilized to increase the range of a wireless power system, including a wireless power system associated with a point of sale display, by isolating a resistive load from the receiver primary trace winding  1122 . In this respect, the receiver primary trace winding  1122  and jumper element  1128  form a free resonating circuit or isolated resonating circuit. The printed ink secondary  1120  can include a pressure sensitive adhesive applied to the flexible, non-conductive substrate opposite the receiver primary and secondary trace windings  1122 ,  1124 . When applied to a surface associated with the point of sale display, the printed ink secondary  1120  provides a source of electrical power to the load when subject to a time varying magnetic flux. The load can include any device associated with a point of sale display, including an LED, an LCD display, a speaker coil, an energy storage device such as a battery or a capacitor, or other point of sale applications as noted herein. 
     In another embodiment, a printed power supply is shown in  FIG. 65  and generally designated  1150 . The printed power supply  1150  can be formed on a flexible, insulating substrate and can include a printed secondary trace winding  1152 , a printed series resonant capacitive element  1154 , a diode  1156 , a smoothing capacitive element  1158 , and a series resistive load  1160 . In the present embodiment, the printed power supply  1150  forms a printed secondary tank circuit for providing a power source to one or more loads  1160  associated with a point of sale display. The printed series resonant capacitive element  1154  can be selected such that the printed power supply  1150  includes a resonant frequency corresponding to the driving or operating frequency of a contactless power supply. That is, the printed series resonant capacitive element  1154  can be selected to tune or otherwise optimize the performance of the printed power supply  1150 . In addition, the diode  1156  can be an LED, and further optionally an OLED. In this respect, the LED  1156 , together with the smoothing capacitive element  1158 , can provide a rectified DC output to a load  1160  while also providing a light output at a relatively low operating voltage. The load  1160  can include any device associated with a point of sale display, including an additional LED, an e-ink display, an LCD display, a speaker coil, and an energy storage device such as a battery or a capacitor, for example. While described above as providing a rectified voltage to a load  1160 , the printed power supply  1150  can instead provide a regulated output, Vcc, relative to ground, Gnd, as also shown in  FIG. 65 . For example, the printed power supply can suitably provide a 3V DC output for use in connection with a point of sale display. 
     As also shown in  FIG. 65 , the printed power supply  1150  can provide a rectified voltage to an energy storage device, for example a capacitor or a battery  1162 . In this embodiment, the series LED  1156  is electrically connected between a first lead of the inductive winding  1152  and a positive terminal of the battery  1162 , optionally using a conductive epoxy. In like manner, the negative terminal of the battery  1162  is electrically connected to the second lead of the inductive winding  1152 . The LED  1156  functions as a rectifying diode to prevent backflow of power through the inductive winding  1152 . The printed circuit  1150  utilizes the resistance of the inductive winding  1152  in combination with the LED  1156  to facilitate rectification of an AC voltage to charge the energy storage device  1162 . The inductive winding  1152  can include a resistance selected such that the winding  1152  functions as a current limiter for the LED  1156  and the battery  1162 . For example, the inductive winding  1152  can include a resistance of 800 ohms, though other values can also be utilized. Though not shown, the printed power supply  1150  can include a capacitor connected in series between the inductive winding  1152  and the LED  1156 . Optionally, the LED  1156  is operable to indicate the power level of the battery  1162 , or to indicate that the power level of the battery has fallen below a predetermined level. For example, the LED intensity could indicate power level if needed. 
     As also shown in  FIG. 65 , the printed circuit  1150  can include printed shielding  1164  to at least partially shield the battery  1162  from a magnetic flux, thereby minimizing eddy currents in the battery  1162 . A process for assembling the printed circuit of  FIG. 65  can include providing a non-conductive substrate, printing an electromagnetic shielding layer  1164  on at least one surface of the substrate, electrically connecting the inductive winding  1152  to an LED  1156  on a front portion of the substrate, and providing a graphic overlay on the front surface of the substrate. The shielding layer  1164  and the graphic overlay can be coextensive with the substrate to provide a supporting surface for the inductive winding  1152  and LED  1156 . The circuit  1150  can include first and second electrical contacts, e.g., crimped conductive tabs, on the rear surface of the substrate for electrical connection with a battery  1162 . A suitable inductive reader can identify and/or authenticate the printed battery charging circuit  1150  based on its reflected impedance. Upon identification and/or authentication, a contactless power supply can provide power to the printed circuit  1150  according to a predetermined profile, and/or based on the reflected impedance of the printed circuit. 
     As noted above, the printed power supply  1150  can be formed on a flexible insulating substrate. The substrate can include portions of a product, product packaging, or display surface, for example. Alternatively, the substrate can be separate or separable from the product, product packaging, or display surface, and can instead include a pressure sensitive adhesive opposite the printed power supply  1150 . Because the trace elements and LED (or OLED) of the printed power supply are relatively thin, the printed power supply can be readily positionable on a product, product packaging, or display surface with minimal overall effect on the size and weight of the corresponding product, product packaging, or display surface. When subject to a time varying magnetic flux, the resulting DC output can be applied through one or more printed transistors or printed FETs to further add to the functionality of a point of sale display as disclosed herein. 
     In another embodiment, a printed secondary circuit is shown in  FIG. 66  and generally designated  1200 . The secondary circuit  1200  can be formed on a non-conductive flexible substrate and includes a trace winding  1202 , a printed ink capacitor  1204 , first and second carbon printed resistive elements  1206 ,  1208 , and a printed ink jumper  1210  to interconnect end portions of the trace winding across a printed ink insulated layer  1212 . A portion of the substrate  1214 , when flexed, results in a change in impedance of the second carbon printed resistive element  1208 , thereby changing the reflected impedance of the secondary circuit  1200 . In the manner as described above, an inductive reader  102  and/or contactless power supply  700  can identify the change in impedance of the secondary circuit  1200 , and can provide power according to the specific needs of the corresponding product or product packaging. This embodiment can be useful, for example, in identifying the position, weight and/or movement of the product or product packaging on a point of sale display. As optionally shown in  FIG. 67 , the secondary circuit  1200  includes a sensor  1216  that acts as a pressure sensitive switch to cause two traces  1218 ,  1220  to form a closed circuit when the pressure sensitive switch is compressed by a mechanical load  1222 . The varying resistance causes a varying impedance in the secondary circuit  1200 , which can be read by the inductive reader and/or contactless power supply as described above. This can be used to indicate the number of times a product has been touched, and can provide basic feedback for indicating use, help, information, reorder and other inputs to the system from the package or device. 
     In another embodiment, a printed secondary circuit is shown in  FIG. 68  and generally designated  1300 . The printed secondary circuit  1300  includes multiple isolated resonant circuits  1316 ,  1318 ,  1320  for forming a resistor array and including a trace winding  1312 , a series resonant capacitor  1314 , a series resistive element  1326  and a bypass element  1328  to short the resistive element  1326 . The configuration of the resistive element  1326  and the bypass element  1328  may be set by the manufacturer or may be selectable by the user of the product container  1304 . For example, physical switches may be employed to select the state of each bypass element  1328 . The physical switches may be push-buttons, a multi-pole slider switch, or a multi-pole rotary switch. As shown in  FIG. 68 , however, the isolated resonant circuits  1316  are formed from conductive ink on a non-conducting substrate  1330 , where the bypass element  1328  is opened in response to the separation of a portion of the non-conducting substrate. In the event that the user desires to open one of the bypass elements  1328 , a user can tear off a designated portion of the substrate  1330  along a perforation  1332 . In this manner, the state of the “n” number of resonant circuits  1316  can indicate which of 2 n  power levels should be applied to a corresponding product or product container. In addition, the isolated resonant circuits  1316  can overlie each other on a packaging material as shown in  FIG. 69 . Here, the isolated resonant circuits  1316  are separated via corresponding layers of insulating ink  1342  substantially as set forth above in connection with  FIG. 24 . As also shown in  FIG. 70 , both the tear tab and the printed ink capacitor are omitted to illustrate their optional inclusion in the isolated resonant circuit  1300 . In this case, the resonant frequency is determined in part based on the number of turns in the isolated resonant circuit  1300 . In another variation as shown in  FIG. 71 , the isolated resonant circuit  1300  is printed over a coating of magnetic shielding material  1342 , which can also be applied by printing methods. This option may prove beneficial in instances where improved inductive coupling is needed, e.g., in instances where a secondary circuit is applied to a metal package. 
     While the printed secondary circuit  1300  is shown in  FIG. 68  as including three isolated resonant circuits  1316 , the printed secondary circuit  1300  can instead include a single resistor array circuit having a plurality of resistors electrically connected to a single secondary coil. The resistors can be connected in parallel or in series with respect to the secondary coil, and can be selectively added to or removed from the resistor array substantially as set forth above. By selectively adding or removing the resistors to the printed secondary circuit  1300 , the inductive identification profile of the printed secondary circuit  1300  can be selectively controlled. For example, as parallel resistors are removed from the circuit  1300 , the inductive identification profile, and in particular its amplitude, can change to reflect the change in overall impedance. The printed secondary circuit  1300  can also have an initial inductive identification profile having an initial resistance. As resistors (or other impedance elements) are effectively added or removed from the printed secondary circuit  1300 , the inductive identification profile can change to optionally define power needs, product quantities, or other information passively conveyed by the printed secondary circuit  1300 . 
     In the embodiments described in connection with  FIGS. 66-71  above, the isolated resonant circuits can be constructed by printing conductive ink on a package substrate. In instances where multiple layers are desired, the layers can be isolated from each other by printing a non-conductive ink layer between adjacent printed circuits. As shown in  FIG. 72  for example, a first conductive circuit  1394  is positioned between an exterior label  1304  and a portion of the package substrate  1390 . A second conductive circuit  1396  is positioned within the package container, spaced apart from the first conductive circuit  1394  by the packaging substrate  1390 . As alternatively shown in  FIG. 73 , a two layer circuit  1306  can include a first printed secondary circuit  1394  on the exterior of a product packaging  1390  and a second printed secondary circuit  1396  on the interior of a product packaging  1390 . Insulating ink layers  1302  can be spaced apart and disposed over the first and second printed secondary circuits  1394 ,  1396 . The conductive circuits  1394 ,  1396  can also include removal circuit tabs  1306  as described above in connection with  FIG. 68  to increase the available circuit topologies. Each printed secondary circuit  1300  can also include a predetermined inductive identification profile set by the manufacturer. For example, the printed secondary circuit  1300  can be laser tuned to include an inductive identification profile that corresponds to the identity of the intended recipient, for example. Also by example, the printed secondary circuit  1300  can be laser tuned to include a single inductive identification profile which can be subsequently varied by manipulation of the one or more switches and/or isolated resonant circuits noted above, optionally by a manufacturer, a retailer and/or an end user. 
     In another embodiment, a printed product count sensor is shown in  FIG. 74  and generally designated  1400 . The product count sensor  1400  includes a secondary coil  1402  and a printed substrate  1404 . The substrate  1404  may be formed of paperboard, plastic, composite, or any other suitable material. The product count sensor  1400  can also include one or more conductors  1406  electrically connected to the secondary coil  1402  for forming a closed electrical circuit. The conductors  1406  may be printed on the substrate  1404 , adhered using adhesive, or otherwise affixed to the substrate  1404  according to any other suitable technique. The conductors  1406  can extend across perforated sections  1408  in the substrate  1404  that align with product holes  1410  when the lower portion of the substrate  1404  is folded lengthwise over the upper portion of the substrate  1404 . Resistive elements  1412  and capacitive elements  1414  can also be positioned over perforated sections  1408 . An insulator  1416  can extend over the conductors  1406 , the resistive elements  1412  and the capacitive elements  1414 . The product count sensor  1400  may be formed with a product container during its manufacture, or affixed to a product container after its manufacture. 
     The product count sensor  1400  can have an initial impedance when the conductors  1406 , the resistive elements  1412  and the capacitive elements  1414  are generally intact. As the perforated sections  1408  are removed, and with them the overlying conductor  1406 , resistive element  1412  or capacitive element  1414 , the impedance of the product count sensor  1400  can change. This variation in impedance can be measured by a nearby inductive reader. For example, the removal of perforated sections  1408  can correspond to the removal of items from a product display stand. As products are removed, an inductive reader can monitor the change in reflected impedance and correlate the change to the removal of certain products with reference to a look-up table stored in memory. The product amount, product type and unique inductive reader identifier may be transmitted to a central hub  168  and to a network server  174  substantially as set forth above. Accordingly, the printed product count sensor  1400  can allow a dense packaging configuration while overcoming spacing and other limitations associated with standard printed circuits. Alternatively, the removal of select perforated sections  1408  by a retailer can indicate the anticipated expiration date of a package. By optionally using conductive ink rather than copper, and by optionally using tightly overlapping windings that are separated by a thin insulating layer, the desired density and number of layers can be achieved in a cost effective manner. Multiple coils, multiple layers of windings, and multiple electrical circuits can be readily stacked, or can be electrically connected in parallel for improved power handling. These components can be printed directly on a ferromagnetic shielding material in one or more layers according to the desired thickness and density. 
     The above descriptions are those of the current embodiments of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. Any reference to elements in the singular, for example, using the articles “a,” “an,” “the,” or “said,” is not to be construed as limiting the element to the singular.