Patent Publication Number: US-9413057-B2

Title: Mobile wireless communications device with an integrated battery/antenna and related methods

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon prior filed provisional application Ser. No. 61/331,994 filed May 6, 2010, the disclosure of which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure generally relates to the field of wireless communications systems, and, more particularly, to mobile wireless communications devices and related methods. 
     BACKGROUND 
     Mobile wireless communications systems continue to grow in popularity and have become an integral part of both personal and business communications. For example, cellular telephones allow users to place and receive voice calls most anywhere they travel. Moreover, as cellular telephone technology has increased, so too has the functionality of cellular devices and the different types of devices available to users. For example, many cellular devices now incorporate personal digital assistant (PDA) features such as calendars, address books, task lists, etc. Moreover, such multi-function devices may also allow users to wirelessly send and receive electronic mail (email) messages and access the Internet via a cellular network and/or a wireless local area network (WLAN), for example. 
     Some mobile devices also incorporate contactless card technology and/or near field communication (NFC) chips. NFC technology is commonly used for contactless short-range communications based on radio frequency identification (RFID) standards, using magnetic field induction to enable communication between electronic devices, including mobile wireless communications devices. These short-range communications include payment and ticketing, electronic keys, identification, device set-up service and similar information sharing. This short-range wireless communications technology exchanges data between devices over a short distance, such as only a few centimeters. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic block diagram of a mobile wireless communications device in accordance with an exemplary embodiment including an integrated battery/antenna assembly. 
         FIG. 2  is a perspective view of an exemplary integrated battery/antenna for use with the mobile wireless communications device of  FIG. 1 . 
         FIG. 3  is a schematic perspective view of a coiled battery stack for use in the integrated battery/antenna of  FIG. 2 . 
         FIGS. 4-6  are perspective views of different NFC-enabled mobile wireless communications device test configurations in which the mobile wireless communications devices have separate conventional NFC loop antennas, along with corresponding free-space S21 test measurements therefor. 
         FIGS. 7-9  are perspective views of different integrated battery/antenna configurations in accordance with an exemplary implementation, along with corresponding free-space S21 test measurements therefor. 
         FIGS. 10-12 and 13-15  are frequency plots showing detailed measurement data for the test configurations of  FIGS. 4-6 and 7-9 , respectively. 
         FIGS. 16 and 17  are front and rear views, respectively, of a mobile wireless communications device in accordance with an alternative embodiment in which the integrated battery/antenna assembly is used as a frequency modulation (FM) antenna. 
         FIG. 18  is a schematic perspective view of an alternative embodiment of the integrated battery/antenna of  FIG. 3  including a tertiary coil. 
         FIGS. 19, 21, and 23  are perspective views of test configurations for mobile wireless communications devices including integrated batteries/antennas with a tertiary coil, and  FIGS. 20, 22, and 24  are respective frequency plots showing detailed measurement data therefor. 
         FIG. 25  is a schematic block diagram illustrating additional components that may be included in the exemplary mobile wireless communications devices. 
     
    
    
     DETAILED DESCRIPTION 
     The present description is made with reference to the accompanying drawings, in which exemplary embodiments are shown. However, many different embodiments may be used, and thus the description should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete. Like numbers refer to like elements throughout, and prime notation is used to indicate similar elements in alternative embodiments. 
     Generally speaking, a mobile wireless communications device is provided herein which may include a portable housing, a cellular transceiver carried by the portable housing, and a battery carried by the portable housing and comprising a pair of electrodes and an electrolyte therebetween. The mobile wireless communications device may further include a wireless communications circuit carried by the portable housing and configured to wirelessly communicate via at least one of the pair of electrodes. Thus, the electrode(s) of the battery also serves as an antenna for the wireless communication circuit, which may advantageously avoid the need for a separate antenna within the device, and therefore conserves space. 
     More particularly, the wireless communications circuit may be configured to operate via magnetic field induction. By way of example, the wireless communications circuit may comprise a Near Field Communication (NFC) circuit configured to send and receive NFC signals via at least one of the pair of electrodes The wireless communications circuit may also comprise a frequency modulation (FM) circuit configured to receive FM signals via at least one of the pair of electrodes. 
     In one exemplary embodiment, the pair of electrodes and electrolyte may be arranged in a layered stack. Moreover, the layered stack may have at least one fold therein. The mobile wireless communications device may further include at least one tertiary coil adjacent the battery. By way of example, the battery may be positioned within the at least one tertiary coil. Additionally, the mobile wireless communications device may further include a cellular antenna carried by the portable housing and coupled to the cellular transceiver. 
     A related method is provided for making a mobile wireless communications device. The method may include coupling a cellular transceiver, a battery, and a wireless communications circuit to a portable housing, where the battery comprises a pair of electrodes and an electrolyte therebetween. The method may further include configuring the wireless communications circuit to wirelessly communicate via at least one of the pair of electrodes. 
     Referring initially to  FIG. 1 , a mobile wireless communications device  50  (also referred to as a “mobile device” herein) illustratively includes a portable housing  51 , a cellular transceiver  52  carried by the portable housing, and a battery assembly  53  carried by the portable housing and including a pair of electrodes (namely a cathode  54  and an anode  55 ) and an electrolyte  56  therebetween. The mobile device  50  further illustratively includes a wireless communications circuit  57  carried by the portable housing  51  and configured to wirelessly communicate via at least one of the cathode  54  and anode  55 . That is, the battery  53  also functions or doubles as an antenna for the wireless communications circuit  57 , to advantageously conserve scarce space or “real estate” within the mobile device  50 , as will be discussed further below. One or more cellular antennas  58  (e.g., internal or external antennas) may also be carried by the portable housing  51  and coupled to the cellular transceiver  52 . 
     By way of example, the wireless communications circuit  57  may be configured to operate via magnetic field induction, such as an NFC circuit which generates a magnetic field in an active mode to send and receive NFC signals using one or both of the cathode  54  and anode  55 . In accordance with another example, the wireless communications circuit  57  may comprise a frequency modulation (FM) circuit configured to receive FM signals via one or both of the cathode  54  and anode  55 . In some embodiments, the battery  50  may function as both RFID (e.g., NFC) and RF (e.g., FM) antennas. An exemplary mobile device  80  in which the battery  83  is used as an FM antenna is shown in  FIGS. 16 and 17 . 
     Accordingly, the battery  53  advantageously provides an integrated low frequency (e.g., Near Field Communication (NFC)) antenna and battery module which may advantageously provide over a 10 dB peak gain improvement when compared to a conventional NFC coil implementation, while also helping to maintain desired hearing aid compatibility (HAC) performance. 
     By way of background, NFC poses an integration challenge to mobile device designers because of its relatively low frequency of operation (13 MHz), as compared to cellular frequency bands. As a result of the low operating frequency, the physical size of NFC antennas required to achieve such frequencies may be as large as that of the entire mobile device itself in some cases. Furthermore, NFC antennas are often required to co-exist with other antennas in a phone, such as the main (e.g., cellular) antenna(s), WiFi, BlueTooth, GPS, radio (e.g., frequency modulation (FM)), etc. 
     Some mobile device NFC implementations make use of large coils to form a loop antenna. In this way, NFC communication between multiple NFC-enabled devices is achieved by virtue of the magnetic fields coupled between the coil in one device to the coil in the other device. Such an implementation usually requires a large loop area, and it also requires the coil to be placed over a ferrite substrate to avoid “shorting” out the antenna. More specifically, the ferrite serves to increase the electrical length between the loop and the surrounding metallic structure and avoid a situation in which the image currents are out of phase with the loop currents. Furthermore, such implementations do not allow the antenna to be shared for different operating formats or frequencies, such as between the NFC and the FM radio circuits, for example. 
     An exemplary implementation of the battery  53  is shown in  FIGS. 2 and 3 . A typical lithium ion battery includes a cathode sheet  54  and an anode sheet  55  separated by an insulator sheet (not shown in  FIG. 3  for clarity of illustration). The battery  53  illustrated in  FIG. 3  includes a first port with first and second terminals  60 ,  61 , and a second port with first and second terminals  62 ,  63 . The sheet bundle or stack is rolled or folded into a shape specified by the mobile device manufacturer for the given implementation. The specific arrangement shown in  FIG. 3  depicts two sheets intertwined with each other. In transformer terminology, this is known as an Frlan transformer. 
     Applicants have observed that from an electromagnetic perspective, the relatively long roll of sheets behaves like a loop antenna. That is, from an electromagnetic perspective, the battery  53  may be used as an antenna “as is” without any modifications, although the battery size/stack length may be selected to provide desired power and antenna characteristics in different embodiments. These characteristics are demonstrated by near field measurements of an experimental mobile device configuration, which will be discussed further below with reference to  FIGS. 4-15 . 
     The exemplary implementation has an advantage over conventional loop designs in that it combines two of the largest components in a mobile device, i.e., the battery and NFC antenna, so that they occupy the same volume or space. Since the NFC antenna is implemented as a part of the battery  53  and there is not a separate NFC (or FM in some embodiments) antenna coil, this also helps minimize any impact on HAC performance. 
     To validate the above-described operational characteristics, a series of experiments were performed between two conventional NFC-enabled mobile devices, and then the batteries by themselves as NFC antennas. The baseline results and respective test configurations for two NFC-enabled mobile device  70   a ,  70   b  with a separate NFC loop antenna are shown in  FIGS. 4-6 , while the corresponding results using just the batteries  73   a ,  73   b  from the devices as the NFC antennas (i.e., instead of the separate loop coils) are shown in  FIGS. 7-9 . In  FIG. 4 , the mobile device  70   a  is laterally orthogonal to and on top of the mobile device  70   b , in  FIG. 5  the mobile devices are laid flat and back-to-back, and in  FIG. 6  the mobile device  70   a  is vertically orthogonal to and on top of the mobile device  70   b  as shown. The positions of the batteries  73   a ,  73   b  in  FIGS. 7-9  are the same as the mobile devices  70   a ,  70   b  in  FIGS. 4-6 , respectively. 
     The performance is quantified by measuring the free-space S21 (in dB) defined from the terminals of one antenna to the other.  FIGS. 10-12 and 13-15  are frequency plots showing detailed measurement data for the test configurations of  FIGS. 4-6 and 7-9 , respectively. 
     One observation from the testing is that a practical consideration of an integrated battery/antenna is that the radiated performance depends upon the particular battery cell. Furthermore, the battery terminals are connected to both the power system and the radio (i.e., whether an NFC or FM configuration). RF choking of the power system would therefore typically not be used, since the battery directly powers the mobile device power amplifier(s). As a result, there could be a degradation in power amplifier efficiency during transmission caused by voltage spikes developing across chokes, for example, in some configurations, although chokes may still potentially be used in other configurations. 
     Referring additionally to  FIG. 18 , one approach to integration of the battery/antenna  53 ′ with other mobile device components is to introduce a tertiary coil  65 ′. The tertiary coil  65 ′ is wrapped around the battery  53 ′ in a vertical direction in the illustrated embodiment. This extra coil allows the low frequency circuits to be DC decoupled from the power system. A prototype construction with a laterally wrapped tertiary coil is shown in  FIG. 19 , in which mobile devices  70   a ″,  70   b ″ with respective batteries  53   a ″,  53   b ″ and tertiary coils  65   a ″,  65   b ″ are arranged bottom-to-bottom and face down as shown. The corresponding frequency plot showing detailed measurement data for this configuration is provided in  FIG. 20 . A similar test configuration is shown in  FIG. 21 , in which the mobile devices  70   a ″,  70   b ″ were placed face down and vertically aligned one on top of the other. The corresponding frequency plot showing detailed measurement data for this configuration is provided in  FIG. 22 . Still another exemplary test configuration is shown in  FIG. 23 , in which the mobile devices  70   a ′,  70   b ′ are positioned top-to-top and face down, and the corresponding frequency plot showing detailed measurement data for this configuration is provided in  FIG. 24 . 
     Exemplary components that may be used in various embodiments of the above-described mobile wireless communications device are now described with reference to an exemplary mobile wireless communications device  1000  shown in  FIG. 26 . The device  1000  illustratively includes a housing  1200 , a keypad  1400  and an output device  1600 . The output device shown is a display  1600 , which may comprise a full graphic LCD. In some embodiments, display  1600  may comprise a touch-sensitive input and output device. Other types of output devices may alternatively be utilized. A processing device  1800  is contained within the housing  1200  and is coupled between the keypad  1400  and the display  1600 . The processing device  1800  controls the operation of the display  1600 , as well as the overall operation of the mobile device  1000 , in response to actuation of keys on the keypad  1400  by the user. In some embodiments, keypad  1400  may comprise a physical keypad or a virtual keypad (e.g., using a touch-sensitive interface) or both. 
     The housing  1200  may be elongated vertically, or may take on other sizes and shapes (including clamshell housing structures, for example). The keypad  1400  may include a mode selection key, or other hardware or software for switching between text entry and telephony entry. 
     In addition to the processing device  1800 , other parts of the mobile device  1000  are shown schematically in  FIG. 26 . These include a communications subsystem  1001 ; a short-range communications subsystem  1020 ; the keypad  1400  and the display  1600 , along with other input/output devices  1060 ,  1080 ,  1100  and  1120 ; as well as memory devices  1160 ,  1180  and various other device subsystems  1201 . The mobile device  1000  may comprise a two-way RF communications device having voice and data communications capabilities. In addition, the mobile device  1000  may have the capability to communicate with other computer systems via the Internet. 
     Operating system software executed by the processing device  1800  may be stored in a persistent store, such as the flash memory  1160 , but may be stored in other types of memory devices, such as a read only memory (ROM) or similar storage element. In addition, system software, specific device applications, or parts thereof, may be temporarily loaded into a volatile store, such as the random access memory (RAM)  1180 . Communications signals received by the mobile device may also be stored in the RAM  1180 . 
     The processing device  1800 , in addition to its operating system functions, enables execution of software applications or modules  1300 A- 1300 N on the device  1000 , such as software modules for performing various steps or operations. A predetermined set of applications that control basic device operations, such as data and voice communications  1300 A and  1300 B, may be installed on the device  1000  during manufacture. In addition, a personal information manager (PIM) application may be installed during manufacture. The PIM may be capable of organizing and managing data items, such as e-mail, calendar events, voice mails, appointments, and task items. The PIM application may also be capable of sending and receiving data items via a wireless network  1401 . The PIM data items may be seamlessly integrated, synchronized and updated via the wireless network  1401  with the device user&#39;s corresponding data items stored or associated with a host computer system. 
     Communication functions, including data and voice communications, are performed through the communications subsystem  1001 , and possibly through the short-range communications subsystem. The communications subsystem  1001  includes a receiver  1500 , a transmitter  1520 , and one or more antennas  1540  and  1560 . In addition, the communications subsystem  1001  also includes a processing module, such as a digital signal processor (DSP)  1580 , and local oscillators (LOs)  1601 . The specific design and implementation of the communications subsystem  1001  is dependent upon the communications network in which the mobile device  1000  is intended to operate. For example, a mobile device  1000  may include a communications subsystem  1001  designed to operate with the Mobitex™, Data TAC™ or General Packet Radio Service (GPRS) mobile data communications networks, and also designed to operate with any of a variety of voice communications networks, such as AMPS, TDMA, CDMA, WCDMA, PCS, GSM, EDGE, etc. Other types of data and voice networks, both separate and integrated, may also be utilized with the mobile device  1000 . The mobile device  1000  may also be compliant with other communications standards such as GSM, 3G, UMTS, 4G, etc. 
     Network access requirements vary depending upon the type of communication system. For example, in the Mobitex and DataTAC networks, mobile devices are registered on the network using a unique personal identification number or PIN associated with each device. In GPRS networks, however, network access is associated with a subscriber or user of a device. A GPRS device therefore utilizes a subscriber identity module, commonly referred to as a SIM card, in order to operate on a GPRS network. 
     When required network registration or activation procedures have been completed, the mobile device  1000  may send and receive communications signals over the communication network  1401 . Signals received from the communications network  1401  by the antenna  1540  are routed to the receiver  1500 , which provides for signal amplification, frequency down conversion, filtering, channel selection, etc., and may also provide analog to digital conversion. Analog-to-digital conversion of the received signal allows the DSP  1580  to perform more complex communications functions, such as demodulation and decoding. In a similar manner, signals to be transmitted to the network  1401  are processed (e.g. modulated and encoded) by the DSP  1580  and are then provided to the transmitter  1520  for digital to analog conversion, frequency up conversion, filtering, amplification and transmission to the communication network  1401  (or networks) via the antenna  1560 . 
     In addition to processing communications signals, the DSP  1580  provides for control of the receiver  1500  and the transmitter  1520 . For example, gains applied to communications signals in the receiver  1500  and transmitter  1520  may be adaptively controlled through automatic gain control algorithms implemented in the DSP  1580 . 
     In a data communications mode, a received signal, such as a text message or web page download, is processed by the communications subsystem  1001  and is input to the processing device  1800 . The received signal is then further processed by the processing device  1800  for an output to the display  1600 , or alternatively to some other auxiliary I/O device  1060 . A device user may also compose data items, such as e-mail messages, using the keypad  1400  and/or some other auxiliary I/O device  1060 , such as a touchpad, a rocker switch, a thumb-wheel, or some other type of input device. The composed data items may then be transmitted over the communications network  1401  via the communications subsystem  1001 . 
     In a voice communications mode, overall operation of the device is substantially similar to the data communications mode, except that received signals are output to a speaker  1100 , and signals for transmission are generated by a microphone  1120 . Alternative voice or audio I/O subsystems, such as a voice message recording subsystem, may also be implemented on the device  1000 . In addition, the display  1600  may also be utilized in voice communications mode, for example to display the identity of a calling party, the duration of a voice call, or other voice call related information. 
     The short-range communications subsystem enables communication between the mobile device  1000  and other proximate systems or devices, which need not necessarily be similar devices. For example, the short-range communications subsystem may include an infrared device and associated circuits and components, or a Bluetooth™ communications module to provide for communication with similarly-enabled systems and devices. 
     Many modifications and other embodiments will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the disclosure is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included.