Patent Publication Number: US-8531155-B2

Title: Portable electronic device and capacitive charger providing data transfer and associated methods

Description:
RELATED APPLICATIONS 
     This application is a continuation of Ser. No. 13/095,131 filed Apr. 27, 2011, now U.S. Pat. No. 8,120,314 issued Feb. 21, 2012, which, in turn, is a continuation of Ser. No. 12/901,627 filed Oct. 11, 2010 now U.S. Pat. No. 7,952,320 issued May 31, 2011, which, in turn, is a continuation of Ser. No. 12/362,132 filed Jan. 29, 2009, now U.S. Pat. No. 7,812,573 issued Oct. 12, 2010, which, in turn, is a continuation of Ser. No. 11/293,902 filed Dec. 5, 2005, now U.S. Pat. No. 7,511,452 issued Mar. 31, 2009, the entire disclosures of which are hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to the field of portable electronic devices, and, more particularly, to portable electronic devices and battery chargers therefor and associated methods. 
     BACKGROUND OF THE INVENTION 
     Rechargeable batteries are used to power many of today&#39;s portable electronic devices. Rechargeable batteries make the portable electronic device more mobile than a device requiring a plug-in power source and this generally adds convenience for the user. However, recharging the batteries for a portable electronic device may be an inconvenience to the user. 
     For example, a rechargeable battery may carry a limited charge and therefore a user may have to monitor the charge level. Also, a user may have to make arrangements to provide for the charging of the batteries such as by carrying chargers and/or power cords. 
     Compounding these inconveniences for the user is the potential increased power consumption by modern portable electronic devices. Most portable electronic devices provide more functionality than their predecessors, which usually results in increased power consumption. This means more frequent recharging of the batteries of the portable electronic device, which may result in more recharging inconvenience for the user. 
     A number of attempts have been made to address recharging for portable electronic devices. For instance, U.S. Pat. No. 6,756,765 to Bruning discloses a system for the contactless recharging of a portable device. The system includes a capacitive plate in a pad onto which the portable device is placed for recharging. 
     Similarly, U.S. Pat. No. 6,275,681 to Vega et al. discloses a system that includes capacitively coupled capacitor plates for generating an electrostatic field for electrostatic charging of a smart card. The system also includes a charge controller in the rechargeable device for controlling the charging of the battery in the rechargeable device. The charger can also be an electrostatic reader so that it can charge a rechargeable device and communicate with the rechargeable device through the capacitive coupling. 
     Another patent to Vega et al. is U.S. Pat. No. 6,282,407, which discloses active and passive electrostatic transceivers that include capacitive charging plates for electrostatically charging. The system also includes an electrostatic reader that continuously generates and transmits an excitation signal to the medium surrounding the reader. In both of the Vega et al. patents, an embodiment is disclosed where a user can manually activate the electrostatic reader instead of having the reader radiating continuously. 
     Unfortunately for some of the above devices, a user may still need to monitor the charge level of the battery in the portable electronic device. In addition, some of the above devices may require the user to precisely align the electrodes of the charging device with the electrodes in the device being charged. Undesired electromagnetic interference (EMI) may also be generated by capacitive charging arrangements. Also, many portable electronic devices may need to be synchronized with a personal computer (PC) and existing wireless links may not be secure and consume too much power. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic perspective view of the electronic apparatus for communicating with and charging a portable electronic device in a typical work environment. 
         FIG. 2  is a block diagram of the electronic apparatus as shown in  FIG. 1 . 
         FIG. 3  is a schematic cross-sectional view of the electronic apparatus as shown in  FIG. 1 . 
         FIG. 4  is a flow chart illustrating a method of capacitively charging a portable electronic device with a charger. 
         FIG. 5  is a more detailed schematic block diagram of an embodiment of a portable electronic device. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present description is made with reference to the accompanying drawings, in which preferred 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 and multiple prime notation are used to indicate similar elements in alternate embodiments. 
     Generally, an electronic apparatus and method is disclosed for conveniently charging a portable electronic device battery while also providing secure data transfer capability. The electronic apparatus includes a portable electronic device and a charger for capacitively charging the portable electronic device. The portable electronic device comprises a housing, a device data communication unit and an associated battery carried by the housing, and at least one pair of device capacitive electrodes carried by the housing to receive a charging signal to charge the battery. The pair of device capacitive electrodes define a device conductive footprint. The charger includes a base having an area larger than the device conductive footprint and able to receive the portable electronic device thereon in a plurality of different positions, and an array of charger capacitive electrodes carried by the base. A charger controller selectively drives only the charger capacitive electrodes within the device conductive footprint with a charging signal to capacitively charge the battery of the portable electronic device when the portable electronic device is positioned on the base of the charger. A charger data communication unit communicates with the device data communication unit via the charger capacitive electrodes and device capacitive electrodes. 
     The charger controller may sense impedances of the charger capacitive electrodes to determine whether a respective charger capacitive electrode is within the device conductive footprint or not. Also, the charger data communication unit may modulate data onto the device charging signal to communicate with the device data communication unit via the charger and device capacitive electrodes. The device may comprise a processor connected to the device data communication unit, and the device data communication unit may include a device data interface connected to the pair of device capacitive electrodes, a device data transceiver connected to the device data interface to demodulate and decode the data communicated on the charging signal, and a processor interface connected between the device data transceiver and the processor. 
     The charger data communication unit may include a charger data transceiver to modulate and encode the data communicated on the charging signal. As such, the charger data transceiver may modulate the data onto the charging signal using Frequency Shift Keying (FSK) modulation. Also, the charger may include a Universal Serial Bus (USB) connector to connect the charger to a personal computer (PC). The charger controller may also include a charging signal generator, a switching circuit connected between the charging signal generator and the charger capacitive electrodes, a control circuit connected to the switching circuit, a buffer connected between the charging signal generator and the switching circuit, and an impedance detector connected to the buffer and the control circuit. 
     A method is directed to communicating with and capacitively charging a portable electronic device with a charger. The portable electronic device includes a housing, a device data communication unit and associated battery carried by the housing, and at least one pair of device capacitive electrodes carried by the housing to receive a charging signal to charge the battery. Again, the device capacitive electrodes define a device conductive footprint. The charger includes a base having an area larger than the device conductive footprint and able to receive the portable electronic device thereon in a plurality of different positions, an array of charger capacitive electrodes carried by the base, a charger controller connected to the charger capacitive electrodes, and an associated charger data communication unit. 
     The method may include placing the portable electronic device adjacent the charger, and selectively driving, via the charger controller, only the charger capacitive electrodes within the device conductive footprint with a charging signal to capacitively charge the battery of the portable electronic device to thereby capacitively charge the battery of the portable electronic device. The method further includes communicating data between the charger data communication unit and the device data communication unit via the charger capacitive electrodes and device capacitive electrodes. 
     The method may also include sensing, via the charger controller, the impedances of the charger capacitive electrodes to determine whether a respective charger capacitive electrode is within the device conductive footprint. The charger data communication unit may comprise a charger data transceiver, and communicating may include modulating and encoding data, with the charger data transceiver, onto the charging signal. The charger data transceiver may modulate the data onto the charging signal using Frequency Shift Keying (FSK) modulation. The charger may include a Universal Serial Bus (USB) connector, and the method may include connecting the charger to a personal computer (PC) via the USB connector. 
     Referring initially to  FIGS. 1-3 , an electronic apparatus  10  including a portable electronic device  12  and a charger  14  for capacitively charging the portable electronic device is now described. The portable electronic device  10  may be in the form of a cell phone, personal digital assistant (PDA), wireless email device, pager, or the like, for example. The portable electronic device  12  illustratively includes a housing  16 , a battery  18  carried by the housing, and a pair of device capacitive electrodes  20  carried by the housing for charging the battery and defining a device conductive footprint  22 . A charging circuit  21  receives the differential signals from the pair of device capacitive electrodes  20 . Such a charging circuit  21  may include a diode rectifier, DC-DC converter and trickle charge circuit as would be appreciated by those skilled in the art. 
     The portable electronic device  10  includes a processor  60  and a device data communication unit  62  which receives and processes data to be sent from or used by the processor  60  as will be discussed in further detail below. The data communication unit  62  includes a data interface  64  to send/receive signals to/from the device capacitive electrodes  20 . A transceiver  66  modulates/demodulates and encodes/decodes the data to be sent via the interface  64 . A processor interface  68  interfaces with the processor  60  and the transceiver  66 . 
     The housing  16  may further include a housing dielectric layer  17  adjacent the device capacitive electrodes  20 . The device capacitive electrodes  20  are arranged in closely spaced, side-by-side relation. In other embodiments, more than one pair of device electrodes  20  may be provided and/or these electrodes can be arranged in different configurations as will be appreciated by those skilled in the art. 
     The charger  14  illustratively includes a base  24  having an area larger than the device conductive footprint  22  and able to receive the portable electronic device  12  thereon in a plurality of different positions. The charger  14  also includes and an array of charger capacitive electrodes  26  and a base dielectric layer  25  carried by the base  24 . The charger  14  further includes, for example, a charger controller  28  for selectively driving the charger capacitive electrodes  26  within the device conductive footprint  22  with a charging signal sufficient to capacitively charge the battery  18  of the portable electronic device  12 , and not driving charger capacitive electrodes outside the device conductive footprint with the charging signal when the portable electronic device is positioned on the charger  14  to thereby capacitively charge the battery of the portable electronic device while reducing undesired (EMI). 
     To help control the undesired EMI, the charger controller  28  selectively drives the charger capacitive electrodes  26  within the device conductive footprint  22  with a charging signal while not driving the charger capacitive electrodes outside the device conductive footprint. In other words, because the charger capacitive electrodes  26  being driven by the charging signal are covered by the device capacitive electrodes  20 , the device capacitive electrodes function as an EMI shield as will be appreciated by those skilled in the art. As a result, for example, a wireless communication link or the USB communication link  80  between the portable electronic device  12  and the computer  82  will be less likely to be disrupted by the operation of charger  14 . 
     The charger controller  28  may sense impedances, for example, of the charger capacitive electrodes  26  to determine whether a respective charger capacitive electrode is within the device conductive footprint  22  or not. Such sensing permits the charger controller  28  to accommodate the portable electronic device  12  if it is moved across the array of charger capacitive electrodes  26 . The charger controller  28  may sequentially drive the charger capacitive electrodes  26  with a sensing signal to sense impedances thereof as will be appreciated by those skilled in the art. To further reduce EMI while providing efficient charging, the charging signal may have an amplitude at least one hundred times greater than an amplitude of the sensing signal, for example. 
     The charger controller  28  illustratively comprises a charging signal generator  30 , a switching circuit  32  connected between the charging signal generator and the charger capacitive electrodes  26 , and a control circuit  34  connected to the switching circuit. The charger controller  28  further comprises a buffer  36  connected between the charging signal generator  30  and the switching circuit  32 , and an impedance detector  37  connected to the buffer and the control circuit  34 . The control circuit  34  may preferably operate the charging signal generator  30  at a reduced amplitude to serve as a signal generator for the sensing signal, for example. 
     The device capacitive electrodes  20  are driven by an alternating current (sine wave) and receive differential excitation signals from charger base  24 . In other words, when one device capacitive electrode  20  receives a positive potential from the charger capacitive electrodes  26  of the base  24  under such device electrode, the other capacitive electrode  20  receives a negative potential from the charger capacitive electrodes  26  of the base  24  under the other device electrode, and vice versa. To generate the differential excitation signals, the charger capacitive electrodes  26  of the base  24  under one capacitive electrode  20  receive an inverted excitation signal relative to charger capacitive electrodes  26  of the base  24  under the other capacitive electrode  20 . 
     In  FIG. 2 , the buffer  36  produces two excitation signals, one is “normal” and other is “inverted”. Then switching circuit  32  connects the normal signal to charger capacitive electrodes  26  of the base  24  under one capacitive electrode  20 , and the inverted signal is connected to charger capacitive electrodes  26  of the base  24  under the other capacitive electrode  20 . The impedance detector  37  first detects the device conductive footprint  22  relative to the charger capacitive electrodes  26 , then this area is divided in two parts: one connected to the normal excitation signal and other connected to the inverted signal. 
     The charger controller  28  and the portable electronic device  12  can also communicate via the charger capacitive electrodes  26  and the device capacitive electrodes  20  such as to indicate the state of charge of the battery  18  or to provide various other synchronization operations between the device  12  and the computer  82 , for example. The charger  14  is illustratively powered by the computer  82  via the Universal Serial Bus (USB) connection  80 , for example. As such, the charger controller  28  may include a USB connector  76 . In other embodiments, the charger  14  can be powered through a wall transformer or other devices as will be appreciated by those skilled in the art. 
     The control circuit  34  determines which charger capacitive electrodes  26  are within the device conductive footprint  22  by operating the charging signal generator  30  to generate a sensing signal. The impedance detector  36  senses a first impedance when a charger capacitive electrode  26  is within the device conductive footprint  22 , and senses a second impedance when a charger capacitive electrode  26  is not. This sensing data is communicated to the control circuit  34 . 
     The control circuit  34  uses this data to selectively drive the charger capacitive electrodes  26  within the device conductive footprint  22  with the charging signal, which may be about 1 MHz, for example. The charging signal generator  30  generates the charging signal, which is relayed to the buffer  36 . The buffer  36  may be a differential buffer, for example, that generates the charging signal to have two components that are substantially 180 degrees out of phase with each other. The switching circuit  32  receives the charging signal and selects which device capacitive electrodes  20  receive the charging signal. The device capacitive electrodes  20  capacitively receive the charging signals to a charging circuit within the housing  16 , as will be appreciated by those skilled in the art, and the charging circuit charges the battery  18 . 
     To communicate via the charger capacitive electrodes  26 , the charger controller  28  includes a charger data communication unit  70  which includes a transceiver  72  to transmit/receive data to/from the device  12  via the charger capacitive electrodes  26  and device capacitive electrodes  20 . The transceiver  72  preferably modulates and encodes data onto the charging signal provided by the charging signal generator  30  to the switching circuit  32  and charger capacitive electrodes  26 . The device transceiver  66  demodulates and decodes signals at the charging signal carrier frequency to detect information being transmitted by the charger transceiver  72 . An interface  74 , e.g. a USB interface, is provided between the charger data communication unit  70  and the USB connector  76 . 
     In the preferred embodiment, charger transceiver  72  modulates the data onto the carrier or charging signal using Frequency Shift Keying (FSK) modulation, and encodes data using NRZ encoding for communication from the charger transceiver to the device transceiver  66 . It is to be appreciated that other modulation schemes such as Amplitude Modulation (AM), Binary Phase Shift Keying (BPSK), a form of Phase Shift Keying (PSK), and others can also be used to modulate the data onto the charging signal. Other data encoding techniques may also be used as would be appreciated by those skilled in the art. 
     That device data communication unit  62  and the charger data communication unit  70  provide an alternative way to “Blue Tooth” or wirelessly connect to synchronize a handheld device  12  with a PC  82 . This will provide better security, lower cost and lower power consumption compared to a wireless link. Charger  14  recognizes that the handheld device  12  has been placed on it&#39;s surface and establishes PC-USB-handheld link through capacitive coupling by using phase or frequency modulation (for example FSK). Eliminating the need for a Radio Frequency (RF) link to the PC  82  provides a more secure connection. There is a very low RF emission from capacitive electrodes  20 / 26  that is difficult to pick-up and decode. Also, the handheld device  12  receives power from charger  14  during data link, so the battery  18  is not draining but charging at this time. 
     Referring now additionally to the flowchart shown in  FIG. 4 , a method aspect of the invention is now described. The method is for communicating with and capacitively charging the portable electronic device  12  with the charger  14 . As discussed in detail above, the portable electronic device  12  includes a housing  16 , a data communication unit  62  and associated battery  18  carried by the housing, and at least one pair of device capacitive electrodes  20  carried by the housing for charging the battery and defining a device conductive footprint  22 . The charger  14  includes a base  24  having an area larger than the device conductive footprint  22  and able to receive the portable electronic device  12  thereon in a plurality of different positions, an array of charger capacitive electrodes  26  carried by the base, and a charger controller  28  connected to the charger capacitive electrodes. 
     The method starts at Block  40  and includes temporarily placing the portable electronic device  12  adjacent the charger  14  at Block  42 . The charger controller  28  senses the portable electronic device  12  at Block  44 . The charger controller then selectively drives, at Block  46 , the charger capacitive electrodes  26  within the device conductive footprint  22  with a charging signal sufficient to capacitively charge the battery  18  of the portable electronic device  12  and not driving charger capacitive electrodes outside the device conductive footprint with the charging signal to thereby capacitively charge the battery of the portable electronic device while reducing undesired EMI. At block  48  data is communicated between the charger data communication unit  70  and the device data communication unit  62  via the charger capacitive electrodes  26  and device capacitive electrodes  20 . Such communication may include modulating and encoding data, with the charger data transceiver  72 , onto the charging signal, as discussed in detail above. The charger controller  28  continues to sense the charger capacitive electrodes  26  to monitor the location of the portable electronic device at Block  50  before the method ends at Block  52 . 
     Another example of a handheld mobile wireless communications device  1000  that may be used in accordance the present device and method is further described with reference to  FIG. 5 . The device  1000  includes a housing  1200 , a keyboard  1400  and an output device  1600 . The output device shown is a display  1600 , which is preferably a full graphic LCD. Other types of output devices may alternatively be utilized. A processing device  1800  is contained within the housing  1200  and is coupled between the keyboard  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 keyboard  1400  by the user. 
     The housing  1200  may be elongated vertically, or may take on other sizes and shapes (including clamshell housing structures). The keyboard 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. 5 . These include a communications subsystem  1001 ; a short-range communications subsystem  1020 ; the keyboard  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  is preferably a two-way RF communications device having voice and data communications capabilities. In addition, the mobile device  1000  preferably has the capability to communicate with other computer systems via the Internet. 
     Operating system software executed by the processing device  1800  is preferably 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  1300 A- 1300 N on the device  1000 . 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 is preferably capable of organizing and managing data items, such as e-mail, calendar events, voice mails, appointments, and task items. The PIM application is also preferably capable of sending and receiving data items via a wireless network  1401 . Preferably, the PIM data items are 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, PCS, GSM, etc. Other types of data and voice networks, both separate and integrated, may also be utilized with the mobile device  1000 . 
     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 requires 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 keyboard  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 of the invention 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 invention is not to be limited to the specific embodiments disclosed, and that other modifications and embodiments are intended to be included within the scope of the appended claims.