Abstract:
The invention is an induction-based lighting system designed to provide power to model displays and other similar applications. The first part of the system is the wireless Power Mat that is placed under the model houses and used as the base for the village, and contains a primary winding that interacts with secondary windings placed inside display components to provide lighting effects, such as one finds in model Christmas villages. The electrical characteristics of the primary winding can be controlled by a microcontroller to make lights in the models blink or change as a user desires.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    None. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
       [0002]    None. 
       THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    None. 
       INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC 
       [0004]    None. 
       BACKGROUND OF THE INVENTION 
       [0005]    1. Field of the Invention 
         [0006]    The invention concerns wireless inductive lighting systems for models, decorative lighting, and communications using variable frequency power. 
         [0007]    2. Background Art 
         [0008]    During special occasions, many families enjoy setting model displays on mantels or around Christmas trees, such as 18th century villages and manger scenes. The village is made up of multiple building models all with their own light source. Each building is positioned and their light source is connected to a power strip to give the buildings their power. All the power cables are then hidden carefully under a white fabric resembling snow. 
         [0009]    There are many problems with this system. Once the models are positioned and their power cables are connected, it is very time intensive to reposition the models. This requires unplugging the power cable, moving the model, plugging in the power cable and hiding the cable. Also, the large number of power cables all connecting to a single outlet presents a fire hazard as well as risks tripping a circuit breaker. Additionally, efforts to hide all of the power cables are time consuming and is seldom aesthetically pleasing. Lastly, when these models are removed at the end of the season, the large number of power cords make storing the Christmas village very cumbersome. 
         [0010]    One approach to lessen the difficulty is to use battery-powered lighting. However, these devices often experience battery acid leakage and corrosion while in long-term storage between device usage. These displays would benefit greatly by a method of lighting the models that did not involve a power cord for every lighted model or batteries. 
         [0011]    The invention herein described uses inductive power provided by a first winding in a mat, delivered to second windings that are part of the model(s) to be lit. Use of inductive power is well known in electrical engineering; Nikola Tesla first demonstrated such power transfer in the late 19th century. Many systems exist to charge batteries and other devices. However, recent products are seeking to use contactless power transfer, often to charge a mobile phone or other battery-powered device by sitting it on a recharging mat. A primary coil in the mat creates a time varying magnetic field that interacts with and delivers power to a secondary coil in the device to be charged. 
         [0012]    A popular development group for near field inductive power is the Wireless Power Consortium (“WPC”), formed in 2008 to assist companies developing products. The WPC specification, developed less than two years later, defines its own operating parameters to transfer upwards of 5 W using ac frequencies of 100 to 205 kHz, and includes communications between the mat and device being charged. 
         [0013]    The WPC specification is fairly complex, detailing control signals to actuate a primary coil that interacts with a secondary coil in a device to be powered and a digital logic control communication protocol. The Consortium&#39;s specification also includes a definition of a primary coil that is specific in width (40 mm) and thickness (2mm), among other details of construction, including wire gage, shielding, etc. It is aimed at charging an expensive cell phone, and not appropriate for inexpensive lighting systems that are inherently capable of operation under a wide range of electrical conditions. 
         [0014]    What is needed is a lighting system designed to provide power by induction to inexpensive lighting devices. 
       BRIEF SUMMARY OF THE INVENTION 
       [0015]    The invention shown in  FIG. 1  is an induction-based Lighting System  11  designed to provide power to model displays and other similar applications. The first part of the system is the wireless Power Mat  13  that is placed under the model houses and used as the base for the village. The Power Mat  13  replaces the decorative cloth or felt base typically used as the base for the village. The Mat  13  is powered from a standard AC wall adapter or batteries and generates a time-varying magnetic field to inductively power lights through a secondary winding. Mats can be different sizes to suit the avid Christmas decorator along with individuals looking to set up their model quickly. 
         [0016]    The Lighting System uses a small wireless illumination “Tag”  17  that can fit inside the models with a light-emitted diode (“LED”) and other basic circuitry, including a secondary winding that interacts with the mat. This Tag  17  replaces incandescent lights currently in the models, as well as with the power cable that is made unnecessary. Tags  17  are populated with lights of different brightness, color and blinking or flickering features. 
         [0017]    The following explanation discusses one embodiment of the invention, comprising a flexible Christmas village mat that can be rolled for easy storage, and several inductively powered lights. Other applications using the same invention are also discussed. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         [0018]      FIG. 1  shows the Lighting System in use. 
           [0019]      FIG. 2A  shows one embodiment of a Tag&#39;s physical construction. 
           [0020]      FIG. 2B  shows one possible schematic of a Tag. 
           [0021]      FIG. 3  shows the Power Mat construction. 
           [0022]      FIG. 4  is a block diagram of one embodiment of an Advanced Mat. 
           [0023]      FIG. 5  shows a time division block diagram. 
           [0024]      FIG. 6  provides an example of time division frequency switching. 
           [0025]      FIG. 7  shows a method of varying frequencies using superposition. 
           [0026]      FIG. 8  shows a Primary Winding build from five-conductor ribbon cable. 
           [0027]      FIG. 9  shows a block diagram of one embodiment of an Auxiliary Mat. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0028]    The invention described herein builds upon the basic inductive wireless power transfer system (specifically resonant inductive coupling) with enhancements to specifically support a wireless illumination system for models (model rail road sets, Christmas villages), games (illuminated chess sets, children&#39;s play sets with light up cars), furniture (illuminated cups in movie theatres and trendy bars, doll cases, flower vase with light up flowers, kids teapot table or table runner with light up dishes, and aquariums where waterproof Tags are located at the bottom of the aquarium), and flooring (where illuminated shoes and other items that could light up when placed in certain locations). 
         [0029]    As shown in  FIG. 1 , the invention  11  comprises two essential components: a wireless Power Mat  13  and illumination Tags  17 . A Primary Winding  21  is embedded within the Mat  13 , typically not visible to users, but is represented as the inductive Primary Winding  21  in  FIG. 3 . Power is transferred inductively between the Power Mat  13  and multiple Tags  17  simultaneously and Tags  17  can be designed with circuitry to blink or flicker. The Power Mat  13  supports the ability to operate on multiple frequencies using time slicing allowing it to independently control Tags  17  tuned to different frequencies. A more complex Advanced Auxiliary Mat  15  that acts in accordance with sensors and switch inputs is also described, incorporating a Light Sensor  31  to automatically activate in darkness, as well as a Timer  33  and Pushbutton  35  to allow the user to turn it on for a preset period or programmed schedule, or change the frequency with the Pushbutton  35 . 
         [0030]    Finally, a user can employ an Auxiliary Mat  19 , depicted in the electronic representation shown in  FIG. 9 , which is identical to the Power Mat  13 , except that it obtains its power by reacting with the Power Mat&#39;s Primary Winding  21 . The Auxiliary Mat  19  is simply properly placed next to the Power Mat  13 . The Power Mat&#39;s Primary Winding  21  delivers power to the winding in the Auxiliary Mat  19 , which in turn, provides power to the Tags  17  placed on the Auxiliary Mat  19 . 
         [0031]    Illuminator Tags—As shown in  FIGS. 2A and 2B , the Tags  17  consist of a parallel tuned LC-resonant circuit composed of the Secondary Winding  27  and Tag Capacitor  28 , typically tuned in the neighborhood of 125 kHz, and an LED  25 . The impedance of a parallel tuned resonant circuit approaches infinity at the resonant frequency, which means that the voltage induced in the Tag&#39;s Coil  27  (which is at or near the resonant frequency of the circuit) is not absorbed by the tuned circuit but is instead used by the LED  25  to provide light. The amount of energy absorbed by the Tag  17  from the Power Mat  13  is dependent on many factors including strength of the field, proximity of the Tag  17  to the Mat  13 , orientation of the Tag  17 , number of turns and size of the Tag&#39;s Coil (or Secondary Winding)  27 . Basically, the more magnetic field lines that are cut by the Tag&#39;s Secondary Winding  27 , the more energy that is extracted from the field and available to power the LED  25  and whatever other circuitry is on the Tag  17 . 
         [0032]    The most simple design uses an LED to rectify the alternating current generated in the Secondary Coil  27  of the Tag to power said LED  25 . A more complex tag design would rectify the alternating current generated by the Power Mat  13  to create lighting effects on the Tag  17  such as a flickering fire. To simplify the Tag  17  construction, the Tag&#39;s Secondary Winding  27  is etched onto a circuit Board  24  (shown in  FIG. 2A ) using standard circuit board manufacturing techniques which ensures consistent performance. The LED  25  and Capacitor  28  are also soldered to the Board  24  which provides a convenient structure for the Tag  17 . Additionally, a small commercially available ferrite core inductor can be used instead of an air core coil or circuit-board etched coil allowing a more compact design in some situations. 
         [0033]    As long as the Tag  17  can be placed inside of the Power Mat&#39;s magnetic field, it will illuminate, providing a large number of possibilities in terms of applications since the magnetic field will penetrate most non-conductive materials, including plastic, wood, and glass, allowing the Tag  17  and or the Power Mat  13  to be embedded inside objects and table tops. A single Power Mat  13  can be used to power multiple Tags  17  simultaneously due to the size of the Power Mat&#39;s magnetic field. A multi-frequency mat can be used to control Tags or sets of Tags  17  tuned to different frequencies by changing the frequency or strength of the generated magnetic field for different lengths of times to independently power sets of tuned tags to create lighting effects. For example the 125 KHz Tags could be on steadily, while the 120 KHz Tags blink, and the 115 kHz Tags flicker, emulating the motion of fire. 
         [0034]    Wireless Power Mat Details—The system uses resonant inductive coupling to transfer power from the Power Mat  13  to the Tag  17 . As shown in  FIG. 3 , the Power Mat is powered by a direct-current power source, and consists of an Oscillator  41 , Driver  43 , Mat Capacitor  45 , and a Primary Winding  21  which is embedded in the Power Mat  13 . The Mat Capacitor  45  and Primary Winding  21  make up a series-tuned resonant inductor-capacitor Circuit  22  designed to resonate at 125 kHz in this application. Optional Mat Connectors  23  are indicated on  FIG. 1  that can be used to affix an Auxiliary Mat and hold it in place to receive power from a Power Mat  13  most efficiently; it is assumed that a practitioner in the art can design many types of connectors that would perform this function with ease. Driving the series-resonant Circuit  22  at its resonant frequency minimizes its impedance resulting in maximum current flow through the circuit which results in a maximum magnetic field strength generated by the Primary Winding  21 , providing maximum power transfer between the Power Mat  13  and Tag  17 . The size of the field is determined by the winding dimensions, the current running through the windings, and the number of turns. In this embodiment, the Primary Winding  21  consists of a 14-turn coil of 26 awg enameled copper wire that runs around the perimeter of the Power Mat  13 . Larger systems may require multiple windings, also known as coils. 
         [0035]    To create a field large enough to be useful in this application, the Primary Winding  21  runs along the perimeter of the Power Mat  13 . To date, the largest mat constructed has been 10″ by 44″, but the invention is not restricted to any particular size. Tags  17  are placed inside the perimeter of the Primary Winding  21  or just outside it to ensure they are energized. To make the mat easily stored, the Primary Winding  21  is placed between two neoprene sheets allowing it to be rolled up for storage. Current embodiments have employed hand wound windings but costs can easily be reduced in production by using a printed or foil-based coil. A mundane 12 Vdc desktop power supply provides power to the current embodiment of the Power Mat  13 , but it could be made battery-powered to support use in toys and other portable applications. 
         [0036]    Advanced Power Mat—While the term “mat” is used throughout this specification, the mat could be an actual mat, or a table top or other furniture with a coil and related electronics integrated into the top surface.  FIG. 4  shows a block diagram of this Advanced Power Mat (“Advanced Mat”)  15  with the enhancements ideal for wireless illumination. The system consists of a Microcontroller  51  which controls current through the Primary Winding  21 . It interfaces with a Light Sensor  31  to control the Advanced Mat  15  in low light conditions. It incorporates a Timer  33  and Pushbutton Interface  35  to activate the Timer to allow the user to activate the invention for a programmed period of time. This feature is also useful for games. The Timer can also be used to control the mat at different times of the day. Finally, the Microcontroller  51  has an interface to connect with switches and buttons in support of integrating the invention into toys (e.g. pushing a button could make certain lights blink, dim, or turn on) The Microcontroller  51  generates the 125 kHz waveforms to drive the Primary Winding  21  by operation of a Mat Driver  53 . After the Microcontroller  51  operates the Mat Driver  53  to energize the Mat&#39;s Primary Winding  21 , Tags  17  placed on the Mat&#39;s surface will illuminate. 
         [0037]    In addition to generating a steady 125 kHz signal the Microcontroller  51  can generate other signals at other frequencies, such as 120 kHz and 115 kHz. To effectively drive the series-resonant circuit with the generated signal, the Microcontroller  51  will adjust the resonant frequency of the tuned circuit by switching in additional capacitors (shown in  FIG. 4  as C 1  and C 2 ) in parallel with the fixed capacitor C. 
         [0038]    One method for accomplishing this multi-frequency control is to use time-slicing, a practice known in electrical engineering. For example in  FIGS. 4 and 5 , the microcontroller could generate a signal at 125 kHz driving the series tuned circuit with switches S 1  and S 2  open, then the frequency could be changed to 120 kHz and S 1  could then be closed adding capacitor C 1  in parallel with C, lowering the tuned circuit resonant frequency to 120 kHz. The system will be able to use this technique to power Tags tuned to different frequencies and control tuned tags or groups of tuned tags to create lighting effects such as blinking, dimming, or a flickering fire. The Microcontroller  51  will use time-slicing to sequentially power the Tags  17  of various frequencies. For example, the Mat  15  could generate 125 kHz for 10 ms, then 120 kHz for 10 ms, and 115 kHz for 10 ms, then repeat, powering Tags tuned to 125 kHz, 120 kHz and 115 kHz, respectively. As long as the switching speed is fast enough, the human eye cannot see the flickering. This technique can be easily extended to allow the system to turn off, blink, or dim Tags  17  of a particular frequency. 
         [0039]      FIG. 6  shows an example of how time division frequency switching can be used for illumination. The figure depicts a one-second window of signal generated by an Advanced Mat  15  divided into 100 ms slices. In the example, the 125 kHz signal turns on a white Tag  17 , 120 kHz turns on a blue Tag  17  and 115 kHz turns on a red Tag  17 . The user would see the white tag appear to be steadily illuminated with the blue tag blinking at the beginning of the second and the red tag blinking at the end of the second. 
         [0040]    Another method of controlling and powering Tags  17  of different frequencies is to use the superposition principle where signals with the desired frequencies are summed together and used to drive the series resonant circuit. The sum of the relevant signals, e.g., 125 kHz, 120 kHz, and 115 kHz, can be done in analog hardware as shown in the diagram of  FIG. 7 , or it can be done in a spreadsheet tool such as Excel, and stored in a lookup table on the Microcontroller  51  for output to the series-resonant circuit. The signals can be either sine waves or square waves. To power a Tag  17  tuned to one of the described frequencies the series-resonant circuit would need to be tuned to the desired frequency of operation using the switches, e.g. no switches for 125 kHz, S 1  on=120 KHz, S 2  on=115 kHz. The benefit of this approach is that a signal containing all of the relevant frequencies is used to drive the series-tuned circuit and the proper frequency is selected by simply switching in or out capacitors to tune the series resonant circuit to one of the frequencies, powering a tag or group of tags tuned to the selected frequency. The time-slicing approach discussed above could then be used to create lighting effects by sequentially powering tags tuned to different frequencies. 
         [0041]    Auxiliary Mat—Shown in  FIG. 9 , the Auxiliary Mat  19  consists of a tuned circuit consisting of a Auxiliary Winding  61  and Auxiliary Capacitor  63 . The significant difference between an Auxiliary Mat  19  and a Power Mat  13  is that the Auxiliary Mat  19  has no driver circuit; it is completely passive. The Auxiliary Mat  19  is placed next to the Powered Mat  13  to extend the size of the powered area, and has no independent power source, but inductively couples with the primary mat causing itself to resonate producing another field capable of powering tags. Additionally, when an Auxiliary Mat  19  is placed near a Power Mat  13  the brightness of the Power Mat  13  will be reduced because of the power leeched by the Auxiliary Mat  19  to extend the field. Optional physical connectors can attach the Auxiliary Mat  19  to the Power Mat  13  to ensure it is positioned optimally. 
         [0042]    These features are unique to this application and invention. There is no need for these features in typical induction mats used for charging batteries. Implementing these features would make a power charging mat very inefficient and could possibly damage devices attempting to charge with the system. For example a typical charging mat would not need a light sensor or timer or the ability to use multiple frequencies to blink or flicker lights. Charging mats for cell phones would never include this feature. Thus, the prior art teaches away from the construction of this invention and embodiment. 
         [0043]    In building this embodiment, a method of creating the Primary Winding  21  using multi-conductor ribbon cable has been developed, making it easier to install the system on furniture and other systems.  FIG. 8  shows the construction of a ribbon-cable based Primary Winding  21 . The Interconnect Board  71  has two Insulation Displacement Connectors (IDC)  73   a    73   b . Once the Ribbon Cable  75  is connected to the IDCs  73   a    73   b , the assembly forms a coil usable as a Primary Winding  21  between the Board Output Terminals  79  in the Lighting System  11 . While the interconnect board  71  is shown as a separate entity its functionality could be directly integrated with another circuit board and does not need to be independent. For example a single board could incorporate all of the mat electronics including the connectors and wiring to use a multi conductor ribbon cable for the primary winding  21 . 
         [0044]    The example in  FIG. 8  shows a five-conductor Ribbon Cable  75  but this could be easily extended to  14  or more conductors. To select the number of turns on the coil a Jumper  77  is used to connect the desired number of turns to the output terminals  79 . This system effectively creates a jumper-tunable Primary Winding (inductor)  21  that permits rapid integration with existing furniture such as tables and counter. If this coil system were not used, a custom coil would need to be wound using individual strands of wire, making construction more difficult and time consuming. 
         [0045]    Other Applications for the Lighting System—As stated earlier, wireless illumination system described here could be used for model lighting, illuminated games, and furniture.  FIG. 1  shows the Mat  13  in use with a Tag  17 , Christmas Village Model Home  79 , and Drinking Glass  81 . Further discussion and examples follow.
       a. A restaurant/bar can have a Primary Winding embedded in tables and bar areas and activate different frequencies to create different colors, or blinking in glasses, shot glasses, plates, coasters, check holders, menus, etc. as a signal to its patrons of specials, last call, or other similar restaurant-wide announcements without using a loud-speaker.   b. A user can embed a Primary Winding  21 , Power Mat  13 , or Advanced Mat  15  under an aquarium, and employ frequency switching with a three-color LED that has three different coils tuned to each primary color of the LED to create any desired color.   c. A Christmas village can include the Lighting System  11 , allowing a someone to build, modify and play with the model buildings in a way that is not possible today, due to safety concerns and the possibility of twisted power cords.   d. Poker chips that would illuminate when placed in the center of a poker table.   e. A chess set where the chess board generates a field to illuminate chess pieces.   f. Powered vase with the primary winding located in the base or mouth allowing inductively powered flowers to be illuminated. The flowers would have coils located in the stems and the LED in the flower itself. An advanced mat/winding could be used to control the color or blinking of the flowers.   g. A powered tablecloth that could be placed on an existing table to power dishes, glasses, or other objects.   h. Shoes that could illuminate and/or change color when the wearer walks on a stage or other item with a power mat embedded inside.   i. A car playset using this lighting system could allow cars to light up and or light up with different colors or flash when placed in specific areas of the playset.       
 
         [0055]    While this invention has been described as it is currently built, the invention is not limited to the disclosed embodiments, but can be employed in various equivalent arrangements included within the spirit and scope of the claims. Other embodiments could include the following structure and improvements:
       a. The ribbon cable coil that creates the primary coil could wrap around the mat multiple times for more turns. For example, two turns with ten-conductor ribbon cable is equivalent to 20 actual turns.   b. Other types of multi-conductor cables could be used in the primary winding mat wiring in addition to ribbon cable, such as Cat 5 Ethernet and DB9 serial cables;   c. The Tags could incorporate capacitors or other energy storage devices to allow them to operate for a time after power is removed from the mat, so a tag-equipped glass could continue emitting light while a user drinks from the glass and it is separated from the Primary Winding.   d. System could support auto-tuning of the mat capacitors to maximize performance of the mat&#39;s time varying magnetic field.   e. Ability to connect Power Mats and Auxiliary Mats with physical connectors that ensure proper placement, enlarging the area in which a Tag may be powered.   f. The Power Mat can be integrated into a table, affixing the primary winding set under the table top.   g. The Power Mat can be integrated into toys and play sets to allow other pieces of the play set to illuminate when placed in certain locations or on the set in general.   h. As discussed in the prior examples, tags can be embedded into various objects such as glasses, toys, game pices, clothing/shoes, dishes, and numerous items.