Patent Publication Number: US-10325708-B2

Title: Spiral near field communication (NFC) antenna coil

Description:
BACKGROUND 
     Recently, technologies have arisen that allow near field coupling (e.g., wireless power transfers (WPT) and near field communications (NFC)) between portable devices in close proximity to each other. Such near field coupling functions may use radio frequency (RF) antennas in the devices to transmit and receive electromagnetic signals. Because of user desires (and/or for esthetic reasons) many of these portable devices are small (and becoming smaller), and tend to have exaggerated aspect ratios when viewed from the side. As a result, many of these portable devices incorporate flat antennas, which use coils of conductive material as their radiating antennas for use in near field coupling functions. 
     The NFC Forum is a group of members who develop NFC specifications, ensures interoperability among devices and services, promotes the use of NFC technology and educates the market about it as well. The NFC Forum was formed in 2004 and has over 150 different members ranging from manufacturers, application developers, financial services institutions and more. Some of the main goals of the NFC Forum are to: develop standards-based NFC specifications that define architecture and interoperability parameters for NFC devices and protocols; encourage the development of products using NFC Forum specifications; and work to ensure that products claiming NFC capabilities comply with NFC Forum specifications. 
     NFC coils in readers, card emulation devices and peer to peer devices (e.g. tags, NFC phones/tablets/Ultrabooks/notebooks) come in various sizes and form factors requiring coils of many different sizes. To address analog coil coupling issues due to a large variation in the installed base and anticipated future NFC devices, the NFC forum has defined three reference sizes (i.e., listeners  6 ,  3  and  1 ) for the readers and tag references. Hence, to successfully pass NFC forum certification, a particular device needs to couple consistently with each of the three reference size coils. Since coil coupling depends to a large extent on the relative sizes of the coils at the Transmit (Tx) and Receive (Rx) ends of a coupled system, this requirement to couple well with all three sizes (i.e., types of listeners) and all three types of listeners or pollers pose a challenge to designers. In a reader device for example, optimizing performance with one reference listener coil (e.g., proximity integrated circuit card (PICC)  1 , the largest reference coil), causes performance to deteriorate with the other listeners with smaller coils (i.e., PICC  3  and PICC  6 ). Current solutions for reader coils are all optimized for one size of reference listener and rely on having enough margin to clear thresholds of performance required with the other listeners. Even if this is achieved, the nature of field strength curves in the vicinity of a coil are different, and the user does not experience a consistent user experience when different sized tags are used with a given reader using a conventional antenna. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates portable devices in an example near field coupling arrangement. 
         FIG. 2  illustrates example near field communications (NFC) Forum reference listening devices. 
         FIG. 3  illustrates example sense coils for near field communications (NFC) Forum reference listening devices, and a spiral shaped NFC coil antenna configuration. 
         FIG. 4  illustrates an example integration of a spiral shaped near field communications (NFC) coil antenna configuration in a keyboard area of a portable device. 
         FIG. 5  is an example method to construct a spiral shaped near field communications (NFC) coil antenna for integration in a portable device. 
     
    
    
     The following Detailed Description is provided with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number usually identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items. 
     DETAILED DESCRIPTION 
     This document discloses one or more systems, apparatuses, methods, etc. for integrating a spiral near field communications (NFC) coil antenna to a portable device for consistent coupling with different tags and devices. In an implementation, the NFC coil antenna may include a continuous multiple loops of coil antenna to form a spiral ring shaped antenna (e.g., rectangular shape). In this implementation, the spiral shaped NFC coil antenna may be configured to include a special pattern or design to work with multiple sized tags or readers during NFC related functions. For example, the special pattern or design may include at least three rectangular loops (i.e., spiral turns) with different rectangular loop areas to obtain maximum and efficient coupling between the spiral NFC coil antenna and the multiple sized tags or readers. In an implementation, the multiple sized tags or readers may adopt standard antenna coil designs that are defined by NFC forum for reference listening devices (e.g., NFC Forum defined listeners  6 ,  3  and  1 ). For example, a first tag that adopts the NFC Forum listener  6  may have a coil antenna design that covers a smaller area as compared to a second tag that adopts the NFC Forum listener  3 . In another example, the second tag that adopts the NFC Forum listener  3  may have the coil antenna design that covers smaller area as compared to a third tag that adopts the NFC Forum listener  1 . In other words, the at least three rectangular loops of the spiral shaped NFC coil antenna in the above implementation is configured to include gradual distribution of individual turns such that the individual turn (i.e., rectangular loop) may perform consistent coupling with corresponding sizes for the tags and readers. 
       FIG. 1  illustrates an example arrangement  100  of portable devices for near field coupling. More particularly, users may have a desire to operate near field coupling enabled portable electronic devices and/or other devices in certain ergonomically convenient manners. 
     Examples of such portable devices include, but are not limited to, ultrabooks, a tablet computer, a netbook, a notebook computer, a laptop computer, mobile phone, a cellular phone, a smartphone, a personal digital assistant, a multimedia playback device, a digital music player, a digital video player, a navigational device, a digital camera, and the like. 
     In an implementation,  FIG. 1  shows two users (not shown) operate their NFC-enabled portable devices  102 - 2  and  102 - 4  to perform NFC-related information sharing functions. For example, a front-to-back (not shown), or a back-to-back (not shown) manner may be performed for the NFC communication. In an implementation, the portable devices  102  may accept information from a credit card  104 , a NFC tag  106  (or other similar device) through a spiral shaped NFC coil antenna (not shown). The portable devices  102  may require the spiral shaped NFC coil antenna (not shown) to be integrated in a palm rest (not shown) or in other areas of the portable devices  102 . For example, the spiral shaped NFC coil antenna (not shown) may be integrated underneath a metal chassis of an Ultrabook portable device  102 , or the spiral shaped NFC coil antenna (not shown) may be integrated underneath conductive coating of the portable device  102 . In this example, the portable devices  102  may accept information from a credit card  104  or NFC tag  106  through the spiral shaped NFC coil antenna (not shown). In an implementation, the credit card  104  or the NFC tag  106  may include passive devices with coil antenna designs (not shown) that are defined by NFC Forum standards. For example, the coil antenna designs (not shown) for credit card  104  or the NFC tag  106  may adopt the standard coil antenna configurations for the NFC Forum Listeners  1 ,  3 , and  6 . In this example, the credit card  104  or the NFC tag  106  may contain different coil antenna configurations (not shown) that include different loop areas depending upon which NFC Forum Listeners  6 ,  3 , or  1  is adopted by the credit card  104  or the NFC tag  106 . 
       FIGS. 2(A), 2(B) , and  2 (C) illustrate example listener devices. For example, the listener devices  200  may be NFC Forum reference devices. In an implementation, NFC Forum reference listening devices  200  may allow signals obtained by a polling device such as a spiral shaped NFC coil antenna (not shown) to be analyzed. In this implementation, the NFC Forum reference listening devices  200  each have their own antenna coil designs. For example, NFC Forum listener  6   200 - 2 , NFC Forum listener  3   200 - 4 , and NFC Forum listener  1   200 - 1  are based on outside envelope measurements of International Organization for Standardization (ISO) referenced PICC- 6 , PICC- 3  and PICC-I antenna designations, respectively. The NFC Forum reference listening devices  200  may be equipped with an integrated sense coil  202  and may send back information through load modulation. 
     In an implementation, a sense coil  202 - 2  for the NFC Forum reference listening device  200 - 2  may include an antenna coil design that covers a smaller area as compared to a sense coil  202 - 4  for the NFC Forum reference listening device  200 - 4 . Similarly, the sense coil  202 - 4  for the NFC Forum reference listening device  200 - 4  may include an antenna coil design that covers a lesser area as compared to a sense coil  202 - 6  for the NFC Forum reference listening device  200 - 6 . In this implementation, the covered area may be based upon radii of the NFC Forum reference listening devices  200  that are measured from the middle (not shown) of the sense coils  202 . 
       FIG. 3  illustrates an example configuration for the spiral shaped NFC coil antenna and sense coils  200 . In an implementation, a spiral shaped NFC coil antenna  300  is constructed to include multiple rectangular loops or turns  302 . For example, an innermost layer  302 - 2 , a middle layer  302 - 4 , and an outermost layer  302 - 6  may be tied continuously to form a single spiral shaped NFC coil antenna  300 . In other words, the middle layer  302 - 4  is tied to or a continuity of the innermost layer  302 - 2  while the outermost layer  302 - 6  is tied to or a continuity of the middle layer  302 - 4 . In an implementation, the innermost layer  302 - 2 , middle layer  302 - 4 , and the outermost layer  302 - 6  may be constructed to cover area  304  for the sense coils  202 - 2 ,  202 - 4 , and  202 - 6 , respectively. The areas  304 - 2 ,  304 - 4 , and  304 - 6  may define the different antenna coil designs for NFC Forum listeners  6 ,  3 , and  1 , respectively. In other implementations, the spiral shaped NFC coil antenna  300  may include other shapes such as a circle or uneven shape as long as the areas  304  of the sense coils  202  are approximately covered by individual loop or turns  302  of the spiral shaped NFC coil antenna  300 . 
     In an implementation, the sense coil  202 - 2  with the cover area  304 - 2  includes at least one or more number of turns  306  that were bunch together without regard to spaces between each loop in the turns  306 . For example, the turns  306  may include multiple loops that were confined to almost the same radii (not shown) measured at the center of the sense coil  202 - 2 . In this example, the multiple loops may be spaced thinly to cover the area  304 - 2 . 
     In an implementation, the sense coil  202 - 4  with the cover area  304 - 4  includes at least one or more number of turns  308  that were bunch together without regard to spaces between each loop in the turns  308 . For example, the turns  308  may include multiple loops that were confined to almost the same radii (not shown) measured at the center of the sense coil  202 - 4 . In this example, the multiple loops of the turns  308  may be spaced thinly to cover the area  304 - 4 . 
     In an implementation, the sense coil  202 - 6  with the cover area  304 - 6  includes at one or more number of turns  310  that were bunch together without regard to spaces between each loop in the turns  310 . For example, the turns  310  may include multiple loops that were confined to almost the same radii (not shown) measured at the center of the sense coil  202 - 6 . In this example, the multiple loops of the turns  310  may be spaced thinly to cover the area  304 - 6 . 
     With continuing reference to  FIG. 3 , the innermost layer  302 - 2  may be configured to adopt the area  304 - 2  of the sense coil  202 - 2 . For example, when the sense coil  202 - 2  with the area  304 - 2  comes within vicinity of the spiral shaped NFC coil antenna  300 , a current (not shown) flowing through the innermost layer  302 - 2  may create a magnetic flux that may lead to another current (not shown) flowing through the sense coil  202 - 2 . A resulting mutual inductance (S 21 ) (not shown) between the sense coil  202 - 2  and the spiral shaped NFC coin antenna  300  (particularly the innermost loop  302 - 2 ) may depend upon relative position to each other, magnetic properties of the medium, and the areas (i.e., dimensions) of the two interacting coils. In an implementation, the area (not shown) covered by the innermost layer  302 - 2  may be configured to overlap at least 80% of the area  304 - 2  to maintain an otherwise efficient mutual inductance (S  21 ) (not shown). For example, if the credit card  104  or the NFC tag  106  implements the sense coil  202 - 2  in their coil antennas, then the spiral shaped NFC coil antenna  300  (particularly the innermost layer  302 - 2 ) may be able to create the mutual inductance (S 21 ) (not shown) as described above. 
     In an implementation, the middle layer  302 - 4  may be configured to adopt the area  304 - 4  of the sense coil  202 - 4 . For example, a gradual increase based from the constructed innermost layer  302 - 2  is configured for the turn  302 - 4  of the spiral shaped NFC coil antenna  300  in order to maintain the mutual inductance (S 21 ) (not shown) that may be derived between the innermost layer  302 - 2  and the sense coil  202 - 2  interaction as described above. In this example, the tum  302 - 4  may cover an area (not shown) that overlaps at least 80% of the area  304 - 4  of the sense coil  202 - 4  in order to maintain the mutual inductance (S  21 ) (not shown) described above. In other implementations, the middle layer  302 - 4  and the innermost layer  302 - 2  may be constructed to adopt a ratio between the areas  304 - 4  and  304 - 2  of the sense coils  202 - 4  and  202 - 2 , respectively. 
     In an implementation, the outermost layer  302 - 6  may be configured to adopt the area  304 - 6  of the sense coil  202 - 6 . For example, another gradual increase is configured for the tum  302 - 6  of the spiral shaped NFC coil antenna  300  based on the size of the constructed middle layer  302 - 4 . In this example, the gradual increase may be configured to maintain the mutual inductance (S 21 ) (not shown) that may be derived between the middle layer  302 - 4  and the sense coil  202 - 4  interaction as described above. In other words, the innermost layer  302 - 2 , the middle layer  302 - 4 , and the outermost layer  302 - 4  are constructed to maintain the mutual inductance (S 21 ) (not shown) by having a separate reference between each of them. In an implementation, the tum  302 - 6  may cover an area (not shown) that overlaps at least 80% of the area  304 - 6  of the sense coil  202 - 6 . In other implementations, the outermost layer  302 - 6 , the middle layer  302 - 4  and/or the innermost layer  302 - 2  may be constructed to adopt the ratio between the areas  304  of the sense coils  202 . 
       FIG. 4  illustrates an example integration of the spiral shaped NFC coil antenna  300  to the portable device  102 . In an implementation, spiral shaped NFC coil antenna  300  may be mounted on, embedded in, or otherwise associated with a metallic chassis (e.g., metal free spaces at below trackpad  402  in a keyboard area  402 ) of the portable device  102 . The spiral shaped NFC coil antenna  300  may include a dedicated antenna for NFC purposes. In other words, the spiral shaped NFC coil antenna  300  may be configured to operate on a separate resonant frequency (e.g., 13.56 MHz to implement NFC operations), and independent from another antenna that uses standard frequencies used in wireless communications (e.g., 5 GHz for WiFi signals). The spiral shaped NFC coil antenna  300  may be made out of a printed circuit board (PCB), a flexible printed circuit (FPC), a metal wire, created through a laser direct structuring (LDS) process, or directly embedded to the metal free space below the trackpad  402  of the portable device  102 . 
     In an implementation, an NFC module  404  may be integrated anywhere inside the keypad area  400  or in other areas such us, beside the trackpad area  400 . The NFC module  404  may include transceiver circuitry that processes electrical signal in the spiral shaped NFC coil antenna  300 . For example, the NFC module  402  may be used to provide tuning to the spiral shaped NFC coil antenna  300  for maximum power transfer during transmit or receive operations. In other implementations, the NFC module  404  may be integrated with the spiral shaped NFC coil antenna  300  to form a single module. 
       FIG. 5  shows an example process chart  500  illustrating an example method for constructing a spiral shaped NFC coil antenna to facilitate near field communications. The order in which the method is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the method, or alternate method. Additionally, individual blocks may be deleted from the method without departing from the spirit and scope of the subject matter described herein. Furthermore, the method may be implemented in any suitable hardware, software, firmware, or a combination thereof, without departing from the scope of the invention. 
     At block  502 , constructing an innermost loop of the spiral shaped NFC coil antenna is performed. In an implementation, the innermost loop (e.g., innermost loop  302 - 2 ) of the spiral shaped NFC coil antenna (e.g., spiral shaped NFC coil antenna  300 ) is constructed and/or configured to cover an area (e.g., area  304 - 2 ) of a sense coil (e.g., sense coil  202 - 2 ) for NFC Forum listener  6  (e.g., NFC Forum listener  6   200 - 2 ). In this implementation, the innermost layer  302 - 2  may be configured to overlap at least 80% of the area  304 - 2  of the sense coil  202 - 2  to maintain an otherwise efficient mutual inductance (S  21 ). 
     At block  504 , constructing a middle layer loop that is tied to the innermost loop of the spiral shaped NFC coil antenna is performed. In an implementation, the middle layer loop (e.g., middle layer loop  302 - 4 ) is a continuity of the innermost loop  302 - 2  of the spiral shaped NFC coil antenna  300 . For example, a gradual increase based from the constructed innermost layer  302 - 2  is configured for the middle layer loop  302 - 4  of the spiral shaped NFC coil antenna  300  in order to maintain the mutual inductance (S 21 ) that may be derived between the innermost layer  302 - 2  and the sense coil  202 - 2  interaction as described above. In this example, the middle layer loop  302 - 4  may cover an area that overlaps at least 80% of the area  304 - 4  of the sense coil  202 - 4 . In other implementations, the middle layer  302 - 4  and the innermost layer  302 - 2  may be constructed to adopt a ratio between the areas  304 - 4  and  304 - 2  of the sense coils  202 - 4  and  202 - 2 , respectively. 
     At block  506 , constructing an outermost loop that is tied to the middle layer loop of the spiral shaped NFC coil antenna is performed. In an implementation, the outermost loop (e.g., outermost loop  302 - 6 ) is a continuity of the middle layer loop  302 - 4  and the innermost loop  302 - 2  of the spiral shaped NFC coil antenna  300 . The construction of the outermost loop  302 - 6  may be based from standard coil antenna design (e.g., sense coil  200 - 6 ) for a NFC Forum listener  1  (e.g., NFC Forum listener  1   200 - 6 ). In an implementation, the standard coil antenna design for the NFC Forum listeners  200 - 6 ,  200 - 3 , and  200 - 1 , are progressively larger in size. 
     At block  508 , integrating the spiral shape NFC coil antenna to a portable device. For example, the spiral shape NFC coil antenna  300  is integrated to the portable device  102 . 
     At block  510 , utilizing the spiral shape NFC coil antenna for NFC related operations. 
     Realizations in accordance with the present invention have been described in the context of particular embodiments. These embodiments are meant to be illustrative and not limiting. Many variations, modifications, additions, and improvements are possible. Accordingly, plural instances may be provided for components described herein as a single instance. Boundaries between various components, operations and data stores are somewhat arbitrary, and particular operations are illustrated in the context of specific illustrative configurations. Other allocations of functionality are envisioned and may fall within the scope of claims that follow. Finally, structures and functionality presented as discrete components in the various configurations may be implemented as a combined structure or component. These and other variations, modifications, additions, and improvements may fall within the scope of the invention as defined in the claims that follow.