Abstract:
When the charge of a battery in a mobile telephone is less than a predefined level, a recharge request message or notice is wirelessly transmitted to a charging module. In response, the charging module begins transmitting a radio frequency signal. The mobile telephone receives the radio frequency signal and extracts energy therefrom which is used to recharge the battery. When the charge of the battery is greater than a predetermined level, recharging the battery terminates and a termination message is wirelessly transmitted to the charging module, which responds by discontinuing transmission of the radio frequency signal.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to wireless telephones, such as cellular telephones and smart phones, that communicate wirelessly to the communication network, and more particularly to techniques for recharging the battery or other power source in such telephones. 
     2. Description of the Related Art 
     Cellular telephones are portable, battery powered communication devices in which the battery periodically requires recharging. Recharging is typically accomplished using a charging module that is plugged into a standard electrical outlet. An electrical cord from the charging module is plugged into a connector on the cellular telephone. The cellular telephone remains tethered to the charging module for a period of time, the length of which depends upon the extent to which the battery was depleted. During that time period, the electrical cord limits the extent to which the telephone can be moved with respect to the charging module. 
     During recharging the cellular telephone may be used for communication purposes. It is desirable to enable a cellular telephone to be recharged without being tethered to a charging module. Doing so will permit the telephone to be moved a greater distance away from the charging module and thus facilitate its continued use for communication purposes. 
     SUMMARY OF THE INVENTION 
     A battery in a mobile telephone is recharged by activating a charging module to transmit a radio frequency signal. The mobile telephone receives the radio frequency signal and extracts energy from that signal. The extracted energy is used to electrically recharge the battery. 
     In one aspect of the present invention, the state of charge of the battery is monitored. When the state of charge is less than a first predefined level, a recharge request message is transmitted wirelessly from the mobile telephone. The charging module responds to receiving the recharge request message by transmitting the radio frequency signal. 
     In a further aspect, the charging module responds to receiving the recharge request message by wirelessly transmitting an acknowledgement message. The mobile telephone responds to the acknowledgement message by commencing to recharge the battery. 
     In yet another aspect of the present invention, the mobile telephone monitors the state of charge of the battery while the battery is being recharged. When the state of charge is greater than a second predefined level, the mobile telephone terminates recharging the battery and wirelessly transmits a recharge termination message. The charging module responds to receiving the recharge termination message by ceasing to transmit the radio frequency signal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a battery charging module being used to recharge the battery of a cellular telephone; 
         FIG. 2  is a block schematic diagram of the electronic circuitry for the charging module; and 
         FIG. 3  is a block schematic diagram of the electronic circuitry in the cellular telephone. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a mobile telephone  10  which as used herein refers to a device, such as a cellular telephone or a “smart phone”, that is capable of communicating wirelessly with a communication network. The mobile telephone  10  is recharged by a radio frequency signal  14  transmitted from a charging module  12 . The charging module receives electrical power via a cable  16  that has a plug  18  for insertion into a standard electrical outlet in a building. The charging module  12  utilizes the power received from the cable  16  to transmit the radio frequency signal  14 . 
     The charging module  12  has an on/off switch  20  and an audio annunicator  22  that is any one of several well known devices that emits one or more tones or sound patterns in response to electrical control signals. The charging module  12  also includes an audio speaker  24  and a volume control  26  for playing music or other audio material, as will be described. 
     Referring to  FIG. 2 , the electrical cable  16  is connected to a power supply  30  within the charging module  12 . The power supply  30  is furnishes electrical energy to a conventional transmitter  32  that emits a radio frequency signal via antenna  34 . That signal is in the radio frequency range so as to be receivable by the mobile telephone  10 , however the frequency may be different from radio frequencies used by the mobile telephone for communication purposes. The antenna  34  also is connected to a radio frequency signal receiver  36 . 
     Both the transmitter  32  and the receiver  36  are connected to a controller  38  that may be a conventional microcomputer based device which includes input/output circuits and a memory for storing a software program that governs the operation of the charging module  12 . The memory also provides storage locations for data used by the software program. The controller  38  is connected to the input/output devices  40  of the charging module which include the on/off switch  20 , the annunicator  22 , and indicator lights  23 . The volume control  26  of the input/output devices  40  is connected to an audio circuit  42  that has an output connected to the speaker  24 . The audio circuit  42  may be a broadcast radio receiver, a port for a media player such as an iPod®, or another source of audio material. 
     With reference to  FIG. 3 , the mobile telephone  10  illustratively includes a housing  50 , which can be a static, a flip or sliding type housing commonly used for cellular telephones. Nevertheless, other housing configurations also may be used. 
     The housing  50  contains a main dielectric substrate  52 , such as a printed circuit board substrate, on which is mounted the primary circuitry  54 . That primary circuitry  54 , typically includes a microprocessor  55  a random access memory and a non-volatile memory. A touch screen  56  provides a user interface for controlling the mobile telephone. A keypad also may be provided. An audio input transducer  64 , such as a microphone, and an audio output transducer  66 , such as a speaker, function as an audio interface to the user and are connected to the primary circuitry  54 . 
     Interaction with an external communication network is performed through a radio frequency circuit  60  which includes a digital signal processor, a wireless signal receiver and a wireless signal transmitter that are connected to a multiple frequency band antenna  62 . The antenna  62  is carried within the lower portion of the housing  50 . The specific design and implementation of the radio frequency circuit  60  depends upon the communication network in which the mobile telephone  10  is intended to operate. For example, a device destined for use in North America may be designed to operate within the Mobitex™ mobile communication system or DataTAC™ mobile communication system, whereas a device intended for use in Europe may incorporate a General Packet Radio Service (GPRS) communication subsystem. 
     A battery  70  is carried within the housing  50  for supplying power to the internal components. An energy extractor  68  uses the radio frequency signal received by the mobile telephone  10  to recharge the battery  70 , as will be described in greater detail. 
     The mobile telephone  10  also may comprise an auxiliary input/output devices  58 , such as, for example, a WLAN (e.g., Bluetooth®, IEEE. 802.11) antenna assembly and circuits for WLAN communication capabilities, and/or a satellite positioning system (e.g., GPS, Galileo, etc.) receiver and antenna assembly to provide position location capabilities, as will be appreciated by those skilled in the art. Other examples of auxiliary I/O devices  58  include an electronic camera for imaging capabilities, and an electrical device connector such as for a USB device, a headphone, or a memory card. 
     With continuing reference to  FIG. 3 , the primary circuitry  54  is connected to the power terminals of the battery  70  and periodically senses the voltage across those terminals. That sensing enables the primary circuitry to determine the relative state of charge of the telephone battery. In addition to having a continuous battery level indicator, at several predefined battery charge levels, such as 25%, 50%, 75% and 100% of full charge, the primary circuitry  54  produces an indication of that charge level on the touch screen  56  of the telephone  10 . This notifies the user when the telephone requires recharging and when the recharging process has been completed, i.e., the battery is 100% charged. 
     When the primary circuitry  54  determines that the battery is below 25% of the full charge level, a command is sent to the radio frequency circuit  60  causing that latter component to send a recharge request message via a radio frequency signal that can be received by the charging module  12 . Specifically, the transmitter within the radio frequency circuit  60  is tuned by the primary circuitry  54  to the frequency of the charging module  12 . The radio frequency circuit produces a carrier signal at that radio frequency (RF) and modulates the carrier signal with a message that indicates that the mobile telephone requires recharging. The modulated RF signal is applied to the multiple frequency band antenna  62 . The mobile telephone  10  intermittently transmits this recharge request signal until receiving a response from a charging module  12 . 
     When the mobile telephone  10  is proximate to a charging module  12 , the recharge request signal will be received by the antenna  34  of the charging module, shown in  FIG. 2 . That signal will be detected by the charging module&#39;s receiver  36  which conveys the recharge request message modulated on that signal to the controller  38 . The controller recognizes the recharge request message and responds by sending an acknowledgement message to the transmitter  32  of the charging module. That action causes the transmitter  32  to apply the acknowledgement message to a radio frequency signal that is continuously transmitted via the antenna  34  to the mobile telephone  10 . That signal, designated the recharging radio frequency signal, is relatively intense, thereby carrying sizeable amount of RF energy derived from the power supply  30 . 
     While that intense radio frequency signal is being transmitted, the audio circuit  42  in the charging module  12  plays music or other audio material through speaker  24 , thereby indicating that recharging is taking place. 
     Upon receiving the acknowledgement signal, circuitry of the telephone  10  in  FIG. 3  enters the battery recharging mode. Specifically, the radio frequency circuit  60  receives the RF signal carrying the acknowledgement message and forwards that message to the primary circuitry  54 . The primary circuitry  54  recognizes the message and in response commences the recharging mode. In that mode, the primary circuitry  54  activates the energy extractor  68  to process the incoming radio frequency signal and derives electrical energy therefrom. The energy extractor  68  uses that electrical energy to apply a charging voltage to the battery  70 , thereby recharging the battery. 
     While recharging is occurring, the primary circuitry  54  periodically suspends the action of the energy extractor  68  long enough for the primary circuitry to detect the voltage, and thus the state of charge, of the battery  70 . At various charge levels, such as 50%, 75%, and 100% of the fully charged level, an indication of that charge level is displayed on the touch screen  56 . In addition, different tones or sound patterns can be emitted by the audio output transducer  66  to indicate the present charge level to the user. 
     In the recharging mode, the radio frequency circuit  60  in the mobile telephone  10  monitors the strength of the radio frequency recharging signal. Should the strength of that signal drop below a predefined level, as may occur if the mobile telephone is moved a significant distance away from the charging module  12 , the radio frequency circuit provides an indication of that event to the primary circuitry  54 . The primary circuitry  54  responds by displaying a low signal strength indication on the touch screen  56  and applying a warning tone to the audio output transducer  66 . This alerts to the user, that the mobile telephone  10  has been moved relatively far from the charging module  12  for satisfactory recharging to take place. 
     The strength of the received radio frequency recharging signal dropping below the predefined level also causes the primary circuitry  54  to formulate a low charging signal strength message. The radio frequency circuit  60  transmits that message from the mobile telephone  10  to the charging module  12 . The receiver  36  within the charging module in  FIG. 2  decodes and forwards that low charging signal strength message to the controller  38 . The controller  38  may respond by increasing the signal strength of recharging radio frequency signal being transmitted. Alternatively, if the recharging radio frequency signal cannot be intensified, the charging module may suspend operation providing an indication of that event via lights  23  and the annunicator  22 . Those indications will further alert the user that the phone is farther from the charging module  12  than is desired for proper recharging of the battery  70 . 
     Eventually the battery  70  becomes fully recharged, which state is detected by the primary circuitry  54 . This event causes the primary circuitry  54  to terminate the recharging mode and disable further operation of the energy extractor. At this juncture, the primary circuitry  54  sends a recharge termination message to the radio frequency circuit  60  which applies that message to a radio frequency signal that is sent via the antenna  62  to the charging module  12 . 
     Upon receiving the radio frequency signal with the recharge termination message, the receiver  36  within the charging module  12  decodes and conveys that message to the controller  38 . The controller  38  responds by commanding the transmitter  32  to cease transmitting the recharging radio frequency signal. Termination of the charging operation is then designated by one of the indicators  23  for perception by the user of the cell phone. The charged termination message also causes the controller  38  to turn off the audio circuit  42  playing of audio material, which further indicates to the user that the telephone has become fully charged. Thereafter, the charging module commences a standby mode in which it continues to listen for another recharge request radio frequency signal from the same or a different mobile telephone. 
     The foregoing description was primarily directed to one or more embodiments of the invention. Although some attention has been given to various alternatives within the scope of the invention, it is anticipated that one skilled in the art will likely realize additional alternatives that are now apparent from disclosure of embodiments of the invention. Accordingly, the scope of the invention should be determined from the following claims and not limited by the above disclosure.