Abstract:
A wireless magnetic field communication system working within the range of less than 1.5 m without induction induced interference during listening mode is proposed. The system comprises at least a transmitter and a receiver. Several novel transmitter designs using either active-connection-control solenoid or spin-orbit torque (SOT) based patterned thin film element(s) are proposed. The system has intrinsic high data security level due to its limited working range, as well as large data transfer rate. The system is suitable to establish a temporary off-the grid magnetic field communication network. It also provides a new data communication approach among modules instead of data cable in industry equipment. The system can be used as a standalone or built-in system for communication between devices or modularized components of a system.

Description:
RELATED APPLICATIONS 
     The present application claims of the priority benefit of U.S. Patent Application 62/038,208 filed on Aug. 16, 2014 as provisional patent application, entitled “WIRELESS NEAR FIELD COMMUNICATION SYSTEM”, which is incorporated herein by reference. 
     FIELD OF INVENTION 
     The invention is related to near field communication system. Particularly, the wireless communication system has high data rate in a distance between the pairing systems below 1.5 meters. 
     BACKGROUND ART 
     Data exchange through public cellphone network, WiFi network or personal cloud is convenient, however, there is huge data leakage concern. It is hard for RFID-based NFC devices to establish a secured temporary personal area network to exchange a large amount of data between device to multiple devices (D2MD) or peer to multiple peers (P2MP) due to either its low data rate, or limited bandwidth, or incapable of supporting D2MD or P2MP mode. Although RFID-enabled-pairing Bluetooth or WiFi Direct devices provide high data rate, they are incapable of D2MD and P2MP data exchange and vulnerable to be hacked. Although WiFi hotspot provides D2MD and P2MP data exchange mode, it is not secured due to the long propagating range. Therefore, developing a secured near field communication system with high data rate is very useful for safely exchanging a large amount of data under D2MD and P2MP modes. 
     Developing such a new secured near field communication system with high data rate has various industrial applications such as modular component design for robots, personalized mobile phone. The design and overall cost of the industry automation equipment particularly the vacuum tools, will be greatly simplified and reduced, respectively, by the near field communication system to link the components without data cable. 
     Such new secured near field communication system can be established by wireless magnetic field communication (MFC) technology. One of near field wireless MFC methods has been proposed previously by G. Yi et. al, US 2008/0299904A1 “wireless communication system”. However, there are some issues associated with the design in the above patent: 1) within pairing system, the solenoid closed to receiver/reader during signal reception can generate interfering magnetic field due to Lenz&#39; law to poison the received signal. To eliminate this interference is challenging; 2) such system has limited data rate due to high impedance (particular the inductance limited) of the solenoid-base design. So far, the demonstrated highest data rate is close to 4 Gb/sec or 4 Gfc/sec (fc means flux changes). 
     In this disclosure, we propose several near field magnetic field communication (NF-MFC) solutions to enable a large amount of data exchange securely without the issues mentioned above. 
     SUMMARY OF THE INVENTION 
     In this invention, a new class of near field magnetic field communication (NF-MFC) system is disclosed. The system comprises wireless magnetic field communication hardware subsystem and support software. 
     The software is used to communicate between NF-MFC system and the mothership devices with capability of filtering undesired data. The software system is a security gate to download data from remote cloud devices or upload data to online system. 
     The core of this NF-MFC system is a transceiver comprising a transmitter made by either an active control solenoid with a high permeability magnetic core or spin orbit torque (SOT) based pattern magnetic elements and a receiver made of solid state magnetic field sensor. They are all manufactured by micro fabrication methods on various substrates. One choice of the substrate is Si wafer with built-in electronic circuit of transceiver control system (System-On-Chip, SOC). The electronics for the transceiver is also able to be integrated with transceiver through System-In-Package (SIP). The magnetic field broadcasted by the transmitter is modularized by the coded digital information. The magnetic field receiver picks up the modularized magnetic field signal, and the useful information is obtained from the selected signal by the decoding electronic circuitry system. The magnetic sensor can be magnetoresistive (MR) technology (AMR, or GMR, or TMR), or Hall sensor, or magnetic impedance (MI) sensor. For any given time, the communication between a pair of transceivers is unidirectional and unilateral. The system with multiple pairs of transceivers is capable of bidirectional communication. The solenoid design of transceiver has been demonstrated by the hard disk industry with data rate up to 4 Gbit/sec. Meanwhile the SOT based pattern magnetic element can be flipped by the SOT effect within tens of picoseconds, thus the data rate of SOT based transceiver is able to reach tens of GHz (or tens of Gb/sec). 
     The SOT design eliminates the inductance concern and enables to make a large array structure to release alignment requirement for the system, nevertheless, the SOT design is more suitable for a short distance (&lt;10 cm) communication. On the other hand, the active solenoid control is appropriate for the propagation distance up to 1.5 meter. Such a short casting distance provides capability of data security. Upon the NF-MFC system, a secured off-the-grid multiple joint connection (Table Network™ or Table Cloud™) is able to be established temporarily for data exchange among friends in a private or public environment. The temporary off-the-grid wireless magnetic network can be extended further for data exchange in a party with the assistance of the technology of Stone Skipping Network™ or Skipping Stone Network™. 
     As used herein, the term “or” may be construed in either an inclusive or exclusive sense. Similarly, the term “exemplary” is construed merely to mean an example of something or an exemplar and not necessarily a preferred or ideal means of accomplishing a goal. Additionally, although various exemplary embodiments discussed below focus on quality control of professionals, the embodiments are given merely for clarity and disclosure. Alternative embodiments may employ other systems and methods and are considered as being within the scope of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  one embodiment of the application of current invention/technology between the portable devices, in which proposed device is built as embedded device. 
         FIG. 1B  one embodiment of the applications of current invention/technology—an independent wireless communication system/device, which can be attached on the external and/or communication port of smart phone, or on USB port of desktop, or laptop. 
         FIG. 1C  the concept of Stone Skipping Network™ or Skipping Stone Network™ to establish long distance off-the-grid network via the proposed invention/technology for information transfer from device to device. 
         FIG. 1D  one of the embodiments of module to module (M2M) (or inter-module) data communication in modularized devices or robots using the proposed technology. 
         FIG. 1E  one embodiment of the proposed device containing three transmitter-receiver pairs for fast data rate and bilateral data transfer at the same time, particularly useful for intra-module wireless low power communications. 
         FIG. 2  key components of the proposed independent system as shown in  FIG. 1B . 
         FIG. 3A  the prior art of the magnetic communication system in patent disclosure US 2008/0299904 A1. 
         FIG. 3B  the prior art of transmitter design in patent disclosure US 2008/0299904 A1. 
         FIG. 4A  one embodiment of the proposed transmitter designs to eliminate the induction current within the transmitter during listening mode of the system. 
         FIG. 4B  one embodiment of the active control solenoid (for synchronous transmitting) designs, which has switches without moving parts. 
         FIG. 5A  one of the embodiments of the transmitter design based on the spin orbit torque (SOT), also called spin-orbit-coupling or spin-orbit interaction. 
         FIG. 5B  one of the embodiments of the transmitter design based on the spin orbit torque (SOT). 
         FIG. 6A  one of the embodiments of wide lateral range transmitter design—array of patterned SOT elements similar to what is shown in  FIG. 5A . 
         FIG. 6B  one embodiment of multiple transmitters&#39; hemispheric uniform coverage design. 
         FIG. 7A  one embodiment of array of transmitters shown in  FIG. 5B  with patterned switchable elements on a flexible substrate. 
         FIG. 7B  the cross section view of the array of transmitters on rolled substrate. 
         FIG. 8  one embodiment of array of mixed transmitters shown in  FIG. 5A  and  FIG. 5B  with different magnetization orientation (either in-plane or out-of-plane)—(A) the bird eye view; (B) cross sectional view along A-A′ cut. 
     
    
    
     DETAILED DESCRIPTION 
     The following numerous specific detailed descriptions are set forth to provide a thorough understanding of various embodiment of the present disclosure. It will be apparent to one skilled in the art, however, that these specific details need not be employed to practice various embodiments of the present disclosure. In other instances, well known components or methods have not been described. 
       FIG. 1A  shows one embodiment of the applications of the proposed NF-MFC technology between the portable devices, in which our invented NF-MFC systems as embedded devices are built. In this particular case, two smart phones ( 1001  and  1002 ) with built-in devices proposed here is capable of communicating through the magnetic field shown as  1003  and  1004  emitted by the built-in NF-MFC system. 
       FIG. 1B  shows one embodiment of the application of the proposed NF-MFC technology. As shown in  FIG. 1B , the independent NF-MFC device  1012  emits magnetic field  1013 , through which a bidirectional channel can be established. The device  1012  can be plugged into the mothership devices&#39; communication ports, such as smart phone communication port, USB port or lightning port of desktop, laptop or smart TV, etc. As such, the mothership device  1011 , without built-in NF-MFC system as shown in  FIG. 1A , can establish data transfer channel with various devices, which either have a built-in NF-MFC system or are attached with an independent NF-MFC system. 
       FIG. 1C  illustrates the concept of Stone Skipping Network™ or Skipping Stone Network™ to establish long distance off-the-grid network via the proposed invention/technology for information transfer from device to device. As shown in  FIG. 1C , the devices  1021 , which either have a built-in NF-MFC system or are attached with an independent NF-MFC system, are bridged together through magnetic field channel capable of communication between two neighbor devices apart away up to 1.5 meters. The effective working pattern and range  1024  of each device shown in  FIG. 1C  is similar to the wave centered on the landing position of skipping stone. Data or information  1022  can be transferred from device to device in a long distance through the private channel  1023  without any external communication network such as mobile phone network or WiFi network. 
     Both the communication network topology and the working distance of the private channel  1023  shown in  FIG. 1C  are determined by the arrangement of the active devices  1021 . When hosts of the active devices are around a table, and the working coverages among the neighbor devices overlap each other, a secured private communication Table Network™ will be established to cover all of the guests. If a portable device or a storage device with a NF-MFC device is at the center of a table, it can act as a device similar as a hotspot of WiFi to establish a Table Cloud™ private network. Such a NF-MFC enabled temporary Table Network™ or Table Cloud™ has intrinsic high security because of its short working distance. 
       FIG. 1D  shows one of the embodiments of module to module (M2M) (inter-module) data communication in modularized devices or robots based on the proposed NF-MFC technology. In this particular case, the system comprises 3 modules,  1031 ,  1032  and  1033 . Modules  1031  and  1032  have built-in NF-MFC system  1034  and  1037 , respectively. Module  1033  has two built-in NF-MFC systems of  1035  and  1036 . NF-MFC system  1035  is paired with NF-MFC system  1034  working in a very short distance of less than 10 cm to build a communication channel between module  1033  and module  1031 . Module  1033  and module  1032  are connected each other via the pair of NF-MFC systems of  1036  and  1037 . The undesired magnetic field cross-talk between the NF-MFC pair systems of  1035 - 1034  and  1036 - 1037  is automatically filtered by the distance longer than 15 cm between the two pair systems. This is done by design to tune the magnetic field range of the transmitter (magnetic field emitter/generator) and the sensitivity of the receiver (solid magnetic field sensor). Built-in NF-MFC based M2M data communication is a green technology, and will eliminate conventional data cable between the modules, save space and weight, provide freedom to the system designer as well as flexibility to customers, and make maintenance easy. Once the built-in NF-MFC based M2M data communication is used widely in related industries by module manufacturers and standardized, the build of the modularized systems such as cell phones or robots becomes much simpler and more efficient. 
       FIG. 1E  schematically shows one embodiment of the proposed NF-MFC systems containing three transceivers, each of which comprises a transmitter and a receiver, in one device for fast data rate and bidirectional data transfer at the same time, particularly useful for inter-module wireless low power communications. As shown in  FIG. 1E , both systems  1040  and  1041  have three transmitters  1043  for magnetic field broadcasting, and three receivers  1044  for magnetic field detection. Every pair of transmitter and receiver forms a NF-MFC based transceiver, and is isolated from its neighbor by the magnetic shield  1042  in order to minimize the magnetic interference between the adjacent transceiver. To further reduce the magnetic interference, different pair of transceivers can be operated at different frequency. The amplitude of the emitted magnetic field (Solenoid transceiver) is modulated by the coded information, or the switch of magnetic field direction (SOT transceiver) is controlled by the coded information. When all the pairs of transceivers send data unidirectional, i.e., from  1040  to  1041 , this design can increase data rate three times with a possible data buffer memory. This system is also capable of bi-directional communication in the meantime.  FIG. 1E  shows a three-independent transceiver design while the system can also have an alternative design with three transmitters and one receiver. The signal captured by the receiver is deconvoluted and decoded by the corresponding electronic system. 
       FIG. 2  illustrates the key components of the proposed independent NF-MFC system in  FIG. 1B . This system has an electronic Central Process and Control Unit (CPCU)  2001  with its own firmware to coordinate the system components and manipulate the data flow. It is linked to  2002  Apps and Software to facilitate the user interaction through mothership device  2003  for data selection and data encryption. Device  2003  is connected to remote cloud storages or devices  2004 . CPCU  2001  is powered by Power Supply  2005 . The system has optional local storage/memory buffer  2006 . Alternatively, it shares storage and memory buffer with mothership devices  2003  via Apps/Software  2002 . The system has  2007  Electronics for Data Encode, Decode and Channel, which communicates with  2008  Preamp/Driver for Transceiver  2009 , which is a key invention of this disclosure. The transceiver either purposely emits the coded data through magnetic field broadcasting to nearby free space or senses the magnetic field sent by the pairing system&#39;s transmitter. 
       FIG. 3A  and  FIG. 3B  are the prior art of the magnetic communication system and its transmitter design in patent disclosure US 2008/0299904 A1. As shown in  FIG. 3A , the pairing system  3001  and  3004  in the prior art have their own receiver  3003 ,  3006  and transmitter  3002  and  3005 , respectively. It is designed in such a way that the magnetic field generated by transmitter  3002  is received by  3006 , while magnetic field from  3005  is sensed by receiver  3003 . As shown in  FIG. 3B , the design of the transmitter  3002  and  3005  in  FIG. 3A  is a typical solenoid with coil  3011  surrounding a soft magnetic core  3012  linked to current driver  3013 , which is controlled by control electronics to emit magnetic field to the nearby space. However, this transmitter design has one fundamental limitation. As shown in  FIG. 3A , if the system  3001  is in the broadcasting mode while the system  3004  is in the listening mode, the magnetic field signal generated by the transmitter  3002  in the system  3001  will be poisoned by the secondary magnetic field emitted by the transmitter  3005  in the system  3004  due to magnetic induction effect. Considering the distance between transmitter  3005  and receiver  3006  is closer than that between transmitter  3002  and receiver  3006  in most cases, de-convolution of the poisoned signal is challenging, and this interference is so strong that it will cause the failure of communication between system  3001  and  3004 . 
       FIG. 4A  illustrates one embodiment of the proposed transmitter designs to eliminate the induction current within the transmitter during listening mode. The key invention of the proposed transmitter design is to turn off synchronously the transmitter during listening mode. The transmitter is a solenoid  4001 , comprising a coil  4002  and a soft magnetic core  4003 , which boosts the emitted magnetic field. The working current of the transmitter is supplied through the coil lead  4004 . Each turn of the coil  4002  links with a switch  4005 . The switch  4005  is controlled by a switch controller  4006 . Therefore, the ON/OFF of the transmitter is synchronized with the system&#39;s working mode by the switching controller  4006 . The transmitter is turned OFF when the system is in listening mode. Hence, there is no secondary magnetic field generated by induction current to poison the incoming signal. On the other hand, the transmitter is turned ON when the system is in a broadcasting mode. 
     There are lots of design choices of switch  4005 , such as RF microelectronic switches, microelectromechanical systems (MEMES) switches, switched capacitors, varactors, high-electron-mobility transistor (HEMT), field effect transistor (FET), and PIN diodes, etc. The rich varieties of the switch designs can be simply classified into two broad catalogs: one with mechanical moving parts; the other one without mechanical moving parts. However, the core of the invented transmitter design shown in  FIG. 4A  is synchronous control of the solenoid transmitter&#39;s ON/OFF with the system&#39;s working modes. 
       FIG. 4B  shows one embodiment of the active-synchronous-control solenoid designs, which has the switches without moving parts. As shown in  FIG. 4B , the transmitter is an active-synchronous control solenoid  4010 , comprising a coil  4011  and a soft magnetic core  4012 . The working current of the solenoid  4010  is supplied through the coil lead  4013 . Each turn of the coil  4011  links with a transistor  4014  that acts as switch. All transistors  4014  have a common gate configuration controlled by transistor controller  4015 . Transistor controller  4015  will turn off the solenoid transmitter  4010  by switching off the transistors  4014  synchronously when the system works in listening mode to prevent induction current generation in coil  4011 . Transistor controller  4015  will turn on the solenoid transmitter  4010  by switching on the transistors  4014  when the system works in broadcasting mode. 
       FIG. 5A  illustrates one of the embodiments for the transmitter design based on the spin orbit torque (SOT), also called spin-orbit-coupling or spin-orbit interaction. As shown in  FIG. 5A , the SOT transmitter comprises an active patterned magnetic element  5001  with perpendicular magnetization as shown by up-and-down arrows; a heavy metal lead  5002  below  5001 , in which a driving current  5003  can be switched from left to right and (or) vice versa labeled by the arrows; a bias magnet  5005  providing in-plane bias field for active patterned element  5001 ; an optional but important soft-underlay structure  5006  to pull the magnetic charge  5007  and  5008  formed at the surface of the active element  5001  further apart via magnetic charge neutralization with charge  5009  and induced charge  5010 . The soft-underlay structure  5006  enables the magnetic field  5004  generated by the active element  5001  to be broadcasted to longer distance in the free space. The direction of the driving current  5003  along with the material choice of the metal lead  5002  and bias field direction provided by bias magnet  5005  determinates the magnetization direction in the patterned element  5001  indicated by the up-and-down arrows in element  5001  due to the so-called SOT effects. The heavy metal lead  5002  can be made of Pt, β-W, β-Ta and other transition heavy metal with large spin Hall effects. 
       FIG. 5B  shows one of the embodiments of the transmitter design based on the spin orbit torque (SOT). As shown in  FIG. 5B , the transmitter comprises an active patterned magnetic element  5011  with in-plane magnetization labeled by in-plane arrows; a heavy metal lead  5012  below  5011 , in which a driving current  5013  can be switched from left to right and (or) vice versa; a bias magnet  5015  providing in-plane bias field for active patterned element  5011 . The direction of the driving current  5013  along with the material choice of the metal lead  5012  and bias field direction provided by the bias magnet  5015  determinates the magnetization direction in the patterned element  5011  indicated by the arrows in the element  5011  due to the so-called SOT effects. The heavy metal lead  5012  can be made of Pt, β-W, β-Ta and other transition heavy metal with large spin Hall effects. 
       FIG. 6A  shows one of the embodiments of the wide lateral range transmitter design  6000  using array of individual transmitters  6001  shown in  FIG. 5A  (the transmitter shown in  FIG. 5B  can also be used in the similar fashion, which is not shown here). The driving current leads  6002  shown in  FIG. 6A  in light gray color is made of heavy metal such as Pt, β-W, β-Ta and other transition heavy metal with large spin Hall effects. The magnetization of the array of individual transmitters  6001  sitting on driving current leads  6002  is controlled by the driving current direction  6003  in leads  6002 . In order to synchronize all the individual transmitters  6001  by using one driving current; as well as simplify the array manufacture process, two neighbor driving current leads  6002  are linked together by a high conductivity metal lead  6005  to form an “S” shape lead arrangement shown in  FIG. 6A . Hence, driven by one current, the array of individual transmitters  6001  will generate synchronized magnetic fields. The superposition of all synchronized magnetic fields forms the broadcasting magnetic field  6004 , which has wide lateral coverage without significant increase of the driving current, making the paring system&#39;s receiver  6006  easily pick up the broadcasting signal with good quality under the conditions of loose alignment to the transmitter array. 
       FIG. 6B  shows a hemispheric uniform coverage transmitter configuration  6010  made of multiple transmitters  6011  with patterned switchable elements on the side and top surfaces of a square frustum, which can reduce the angle sensitivity of the pairing system&#39;s receiver (sensor)  6016  relatively oriented to the transmitter  6010 . Both the transmitters shown in  FIG. 5A  and  FIG. 5B  can be used to make transmitter configuration  6010 . As shown in  FIG. 6B , array of transmitters  6011  with patterned magnetic elements are arranged on the side and top surfaces of the square frustum feature  6015  directly sitting on the heavy metal leads  6012 , which carries the driving current  6013 . The magnetization of the patterned magnetic elements in transmitter  6011  follows the direction of driving current  6013 . This configuration provides hemispheric uniform coverage of the magnetic field  6014  broadcasted by the transmitter, and make the paring system&#39;s receiver  6016  less sensitive to the orientation relative to transmitter  6010 . The lead  6012  is made of heavy metal such as Pt, β-W, β-Ta and other transition heavy metal with large spin Hall effects. 
       FIG. 7A  shows one of embodiments of transmitter designs on the flexible substrate using array of transmitters shown in  FIG. 5B  with patterned switchable elements.  FIG. 7B  is the cross section view of the array of transmitters on the rolled substrate. As shown in  FIG. 7A , the patterned magnetic elements  7002  directly connect to the heavy metal lead  7006 , which is laid on the flexible substrate  7001  and made of heavy metal such as Pt, β-W, β-Ta or other transition heavy metal with large spin Hall effects. The magnetization  7003  of the patterned magnetic elements  7002 , marked by the arrows, can be flipped by the driving current  7007  in the lead  7006 . The bias magnet  7004  provides an in-plane bias magnetic field to the patterned magnetic element  7002 . The soft magnetic feature  7005  on the back of pattern magnetic element  7002  is an optional design, but useful to reduce the demagnetic field of the patterned magnetic element  7002  similar to the function of the soft-underlay structure  5006  in  FIG. 5A . The two ends  7008  and  7009  of the flexible substrate are marked as X and Y, respectively. Shown in  FIG. 7B , the end  7008  (Mark X) is on the outside of the rolled substrate, and the end  7009  (Mark Y) is at the center of the rolled substrate. The driving current  7007  is supplied to the rolled transmitter via both ends of  7008  (Mark X) and  7009  (Mark Y). 
       FIG. 8  illustrates transmitter design with array of mixed transmitters shown in  FIG. 5A  and  FIG. 5B  with different magnetization orientation (either in-plane or out-of-plane)—(A) the bird eye view; (B) cross section view along A-A′ cut. As shown in  FIG. 8 , the new transmitter  8000  comprises heavy metal leads  8001 , over which there are two kinds of patterned magnetic elements  8006  and  8002  shown in  FIG. 5A  and  FIG. 5B , respectively. For the sake of simplicity, the bias hard magnets shown in  FIG. 5A  and  FIG. 5B  are not shown here. The magnetizations of the patterned elements  8002  and  8006 , which generate the emitted magnetic field  8004  and  8005 , respectively, can be switched by the driving current  8003  in heavy metal lead  8001  according with the code information. This design makes the emitted magnetic field cover two orthogonal directions thus remarkably reduce the orientation alignment requirement between the transmitter and the receiver in its pairing system.