Abstract:
In a contactless charging system charging energy is transferred across an inductive coupler to charge a battery ( 21 ) of a portable device, such as a two-way radio, cellular phone, paging device, or wireless communicator. The inductive coupler also provides a way for communicating at least one signal, such as to improve the charging process and the transfer of charging energy. Charging efficiency is improved by voltage regulation using feedback through the inductive coupler, or via a wireless RF link, and a controller ( 11 ) in-circuit with the primary side ( 12 ) of the inductive coupler. The controller ( 11 ) may communicate information signals via inductive coupling, or via a wireless RF link, for communicating with other devices such as smart cards and microphones or for control or data transfer.

Description:
TECHNICAL FIELD 
     This invention generally relates to the field of contactless battery chargers for portable devices, and more particularly to contactlessly charging a battery of a portable device while wirelessly coupling control and data signaling between devices. 
     DESCRIPTION OF THE PRIOR ART 
     Contactless electrical connections are well known in the field of portable electrical devices. For example, portable motorized toothbrushes typically contain a rechargeable battery which is charged by induction. Similarly, portable wireless communication devices, such as two-way RF radios, cellular phones, paging devices, and wireless communicators, commonly utilize a rechargeable battery that, in certain applications, is recharged by contactless induction charging. This conventional contactless charging normally is a one-way delivery of charging energy without any feedback control to the charger unit from the device being recharged. Unfortunately, this type of one-way contactless, or induction, charging can be slow, inefficient, and wasteful of energy. 
     Nevertheless, portable applications are becoming more popular because of the convenience afforded a user by working without a wired connection, such as not having to connect plugs to sockets, not having to precisely locate and plug a unit to be charged, and the ability to quickly “grab-n-go” remove from a charger unit a device that has been charged up. A primary disadvantage, however, is the inefficiency of charging portable devices via a one-way contactless interface. For example, in induction coupling, battery charging efficiencies of about 60% are typical and achievement of that efficiency usually requires clearances of 3 mm between the supply and load coils. The lower efficiency results in longer charge times and more wasted energy to charge devices. 
     In typical induction coupled charging systems, the best efficiencies have been achieved in products that have produced about 5 watts of power output and require high cost or high precision systems for induction coupling and resonant converter topology. Therefore, higher cost for charging arrangements, and longer times to charge a unit while wasting more energy, are drawbacks of conventional systems. 
     Accordingly, what is needed is a lower cost, more efficient induction coupled system capable of efficiently transferring electrical energy to the battery, such as capable of producing more than 5 watts of output power. 
     SUMMARY OF THE INVENTION 
     Improvements in battery technology for portable electronic devices have produced longer battery life and higher power outputs. While the Lithium Ion battery has increased the quality of power available for portable devices, its maximum charging potential is reached where battery charging methods permit higher efficiencies according to a charging profile. Additionally, in some cases it would be desirable to follow a charging profile to properly charge a battery. That is, the charging unit following an optimum charging curve would more efficiently deliver energy to charge a battery. According to the preferred embodiments of the present invention, a feedback control signal indicative of a charging state of a battery in a portable device is provided to a charging control circuit in a charger base device to control a contactless battery charging system thereby controlling the amount of energy being transferred to the battery. This advantageously improves the efficiency of the charging process. The transfer of energy for contactless charging the battery is preferably accomplished across inductively coupled coils between the charger base device and the portable device containing the battery. In a preferred embodiment of the present invention, the feedback control signal is coupled to the charging control circuit via an inductive link to regulate a charging circuit and the energy being transferred via inductive coupling to the battery. In an alternative preferred embodiment, an RF loop can be used for communicating control and data signals. 
     In the use of an RF loop, sufficient bandwidth would normally be available to accommodate each of the side bands carrying information between the primary and secondary, as in the application of frequency division multiplexing or frequency skipping or hopping or alternatively, a system of time division multiplexing could be used, as would be well known to one of ordinary skill in the art. The RF loop could be used, for example, to control and/or communicate data signals with wireless smart cards or wireless microphones or other devices in or connected to the portable device. 
     According to a preferred embodiment of the present invention, a contactless charging system with feedback control includes an inductive coupler for transferring energy from a primary side of the inductive coupler to a secondary side of the inductive coupler. A first primary controller coupled to the primary side of the inductive coupler controls the energy to the inductive coupler. A first secondary device is coupled to the secondary side of the inductive coupler to receive the energy transferred by the inductive coupler. A first sensing device is coupled to the secondary side of the inductive coupler for producing a first signal indicative of the energy received by the first secondary device. The inductive coupler can transfer the first signal indicative of the energy received by the first secondary device to the primary side and to the primary controller for controlling the energy transferred to the secondary side, responsive to the first signal. 
     Further disclosed according to an alternative preferred embodiment of the present invention is a charging system utilizing wireless feed back of control signaling and communicating data signaling with at least one portable device. The charging system, for example, includes a charger base device that can control at least one operating function in a portable device. The portable device preferably includes an encoder and an RF transmitter for encoding and transmitting the feedback signal and the base device includes an RF receiver and a decoder. Preferably, the portable device also includes an RF receiver and a decoder, and the base device includes an encoder and an RF transmitter. The portable device wirelessly transmits, for example, an encoded feedback signal to the base device that receives and decodes the feedback signal to control a charging operation. Further, the charging device wirelessly transmits an encoded data signal to the portable device that receives and decodes the data signal. The portable device, for example, controls functions in the device according to the data signal. 
     Additionally disclosed according to an alternative embodiment of the present invention is a method of driving the primary of an inductive coupler with an alternating current being regulated at least in part according to a sensed voltage of a battery being charged via the secondary of the inductive coupler. The method includes the steps of driving the primary of an inductive coupler with an alternating current, receiving an alternating current in the secondary of the inductive coupler and producing a direct current, connecting the direct current to a battery of a portable device for charging the battery, producing an alternating current in the secondary of the inductive coupler responsive to the voltage level of the battery, receiving in the primary of the inductive coupler the alternating current from the secondary of the inductive coupler responsive to the voltage level of the battery, and regulating the alternating current in the primary side of the inductive coupler in response to the voltage level of the battery. 
     And further disclosed, according to an alternative preferred embodiment of the present invention, is a contactless charging system having a base unit, a portable unit, and a contactless coupler connected to the base unit and to the portable unit for transferring energy from the base unit to a load in the portable unit. The contactless coupler includes a first primary controller in the base unit and a first sensing device in the portable unit. The first sensing device is connected to the load in the portable unit for producing a feedback signal indicative of the energy in the load. The first primary controller regulates the energy transferred from the base unit to the load in response to the feedback signal. The contactless coupler is an inductive coupler. The system has a first communications sensing device electrically coupled to the inductive coupler for producing an information signal indicative of an operating parameter of the portable unit in the inductive coupler. A first communications controller is communicatively coupled to the inductive coupler for receiving the information signal and producing a control signal in the inductive device for controlling the operating parameter in the portable unit. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a prior art inductively coupled battery charger without feed back to control the charging cycle. 
     FIG. 2 shows an improved inductively coupled contactless battery charging system using inductively coupled feedback from the secondary to the primary side to provide control and regulation of the charging cycle and improve the charging efficiency. 
     FIG. 3 shows the improved contactless battery charging system of FIG. 2, using an RF channel or loop to control and/or communicate with one or more devices. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The invention and the inventive principles are described with reference to the preferred embodiments shown in FIGS. 2 and 3. FIG. 1 shows a prior art system for comparison. As illustrated in FIG. 1, an inductively coupled charging system  10  has a primary side or base device  12  and a secondary side or portable device  16 . A primary controller used as a primary charging device  11  as would be well known to one of ordinary skill in the art, is shown connected to the AC power source and to a primary coil  13 . The primary coil  13  is shown inductively coupled to secondary coil  15  by field  14 . The secondary coil  15  is coupled to battery  21  through a secondary charging device which is shown in this example as a rectifier circuit  19 . The battery  21  in turn is connected to the load shown as RL  23 . As would be well known to one of ordinary skill in the art, the energy coupled from the primary coil  13  is applied through the secondary coil  15  to charge the battery  21 . However, no feed back is used in this prior art system, resulting in reduced charging efficiency and energy output of the battery. 
     The preferred embodiments illustrated in FIGS. 2 and 3 are used to show the invention and the inventive principles. In FIGS. 1,  2  and  3 , the same numerals are used for the same or similar parts. As shown in FIG. 2, the output of the secondary charging device  19  is electrically coupled to the battery  21  for the preferred embodiment, which is used to provide power to load RL  23 . As shown in FIG. 2, a sensing device  27  is electrically coupled to the secondary charging device  19  to receive a signal from the secondary charging device  19  indicative of the charging voltage. The sensing device  27  processes this indicating signal to produce a feed back signal for the primary controller device  11 . The feedback control signal is transmitted from the secondary side or portable side  16  to the primary or base side  12  through inductively coupled coils  31  and  29 , coupled by field  17 . Note that in one preferred embodiment, the coils  31  and  29  may be inter-wound on the same core as the coils  15  and  13 . This arrangement would help to reduce the size and cost of a contactless inductive coupling arrangement. However, the coils  31  and  29 , in this example, can be wound on a separate core, or in another inductive coupling arrangement as may be obvious to one of ordinary skill in the art. 
     In an alternative embodiment, the inductive coupling arrangement comprising primary coil  13  and secondary coil  15  could be used to transmit the feedback signal from the secondary side  16  to the primary side  12 . The coils  13  and  15 , in this example, could be used to carry the charging energy signal from the primary coil  13  to the secondary coil  15  and a feedback signal from the secondary coil  15  to the primary coil  13 . 
     An exemplary signal detection device  33  is shown in the primary side  12  connected to primary controller  11  and which provides a signal to the primary controller  11  indicative of the state of the charging process in the secondary  16 . This signal is used by the primary controller  11  to regulate or control the voltage level of a charging signal being applied to the battery  21  as would be obvious, in view of the discussion above, to one of ordinary skill in the art. For example, to control the charging process and improve the charging efficiency, the controller  11  could adjust the voltage and/or cycling of an alternating current charging signal being applied to the primary coil  13  to adjust the energy being transferred to the battery  21 . 
     In an alternative preferred embodiment of the present invention, the sensing device  27  comprises a communication control device  26  that, in this example, is electrically coupled to a device or component  28  in the secondary side  16  of the inductive coupling arrangement. The communication control device  26  preferably comprises a controller electrically coupled to a serial peripheral interface (SPI) or a serial communication interface (SCI) or a universal asynchronous receive and transmit device (UART), for communicating information according to known communication signaling protocols. The device or component  28 , according to this example, may be a microphone or smart card or other communication component in the portable device. The communication control device  26  receives information signals from the device or component  28 , that indicate, for example, operating parameters of the device or component  28 . 
     In the alternative preferred embodiment, the communication control device  26  communicates information signals with the device or component  28 . Information signals received from the device or component  28  indicate at least one operational parameter of the device or component  28 . Information signals transmitted to the device or component  28  can set a value for at least one operational parameter of the device or component  28 . The sensing device  27 , according to this preferred embodiment of the present invention, delivers information signals to the inductive coupling arrangement, such as via the coil  31  and coil  29 , and thereby couple information signals from the device or component  28  in the secondary side  16  and deliver the information signals to the controller  11  in the primary side  12 . Additionally, the controller  11  can deliver information signals to the inductive coupling arrangement, such as via coil  29  and coil  31  at an electrical signaling contact  25 , and thereby inductively couple the information signals to the sensing device  27 , and further thereby couple the information signals from the controller  11  in the primary side  12  and deliver the information signals to the device or component  28  in the secondary side  16 . In this way, as an example of a preferred embodiment of the present invention, information signaling can be bi-directionally communicated between the controller  11  in the primary side  12  and the device or component  28  in the secondary side  16 . The controller  11  monitors, for example, the received information signals to monitor the operating parameters of the device or component  28 . 
     For example, the controller  11  may monitor the operating parameter of the device or component  28  comprising a smart card device in the portable device to verify whether a financial transaction was successfully initiated by the smart card device. As an alternative example, an operational status of the smart card device may be indicated in the information signal to the controller  11 . The controller  11  in this way can track an operational state of the smart card device. Additionally, the controller  11  can transmit at least one information signal to the device or component  28  to set an operational parameter of the device or component  28 . Preferably, the controller  11  controls and sets at least one operational parameter of the device or component  28  in response to monitoring at least one information signal received from the device or component  28  wherein the at least one information signal comprises a value associated with the at least one operational parameter of the device or component  28 . For example, the configuration of operational parameters for a smart card device can be controlled and set by the controller  11  by communicating the information signals between the controller  11  and the device or component  28  comprising a smart card device. As will be appreciated by those of ordinary skill in the art, it is particularly valuable to be able to communicate information signals with a portable device contemporaneous with providing a charging energy to a power source, for example a battery  21 , associated with the portable device. 
     As shown in FIG. 3, the principles of the invention may be applied to couple a feedback signal from a secondary side  16  to a primary side  12  across a contactless charging interface by utilizing a local RF link. Additionally, information signals can be communicated between the primary side  12  and the secondary side  16  by utilizing a local RF link. In this way, information signals, for example, associated with operating parameters of various secondary devices in the secondary side  16 , may be communicated with a controller  11  in the primary side  12 , such as for purposes of control and/or for communicating data signals. 
     Referring to FIG. 3, the secondary charging device  19  is electrically coupled to a sensing device  38  which provides to a radio transceiver  35  a feedback signal indicative of a charging parameter of the secondary charging device  19 , such as indicative of a charging voltage, as described above. The radio transceiver  35  preferably comprises an encoder/decoder to encode a signal for radio transmission or to decode a signal received from the antenna  37 . An RF encoded signal, in this example, is then broadcast transmitted through antenna  37  and received by antenna  52  and coupled to radio transceiver  39 . The radio transceiver  39  preferably comprises and encoder/decoder to encode a signal for radio transmission or to decode a signal received from the antenna  52 . After the radio transceiver  39  receives and decodes a received signal, the transceiver  39  electrically couples the decoded signal as a feedback signal to the primary controller  11 . 
     The primary controller  11  then uses the feedback control signal, such as to regulate a parameter of the charging process, a charging signal voltage, and/or a cycling rate, and thereby improving the efficiency of the overall charging process and the energy transfer to the battery  21 . In a similar manner, information or feedback signals for indicating the state of operating parameters of devices or components in the portable device, such as a microphone or smart card or other communication component in the portable device, may be encoded and transmitted as an RF encoded signal. As illustrated in FIG. 3, within communication control block  47  are shown three exemplary communication control devices,  40 ,  42  and  44 , that are electrically coupled to the radio transceiver  35 . Each of the communication control devices,  40 ,  42  and  44 , for example, may comprise a controller electrically coupled to a serial peripheral interface (SPI) or a serial communication interface (SCI) or a universal asynchronous receive and transmit device (UART), for communicating information according to known communication signaling protocols. For example, such a signaling protocol for local area wireless communication may comprise an industry protocol specification generally referred to as Bluetooth. 
     Each of the communication control devices  40 ,  42 , and  44 , in this example, is electrically coupled to a device or component in the secondary side  16 , shown as  49 ,  50  and  51 . The respective device or component  49 ,  50  and  51 , according to this example, may be a microphone or smart card or other communication component in the portable device. The communication control devices  40 ,  42 , and  44 , receive information signals from respective devices or components  49 ,  50  and  51 , that indicate, for example, operating parameters of the respective devices or components  49 ,  50  and  51 . 
     The communication control devices  40 ,  42 , and  44 , couple the respective received information signals to the radio transceiver  35  to broadcast transmit the information signals. In a preferred embodiment, the transmitted information signals are received by the antenna  52  of the radio transceiver  39  and coupled to the controller  11 . The controller  11  monitors the information signals to monitor the operating parameters of the respective devices or components  49 ,  50  and  51 . For example, the controller  11  may monitor the operating parameter of a smart card device in the portable device to verify whether a financial transaction was successfully initiated by the smart card device. As an alternative example, an operational status of the smart card device may be indicated in the information signal to the controller  11 . The controller  11  in this way can track an operational state of the smart card device. 
     The controller  11 , according to the preferred embodiment of the present invention, can couple an information signal to the radio transceiver  39  to broadcast transmit an information signal via the antenna  52 . The radio transceiver  35  receives the transmitted information signal via the antenna  37 . the radio transceiver  35  then couples the received information signal to at least one of the communication control devices  40 ,  42 , and  44 , that then couple the respective received information signal to the respective devices or components  49 ,  50  and  51 . For example, the controller  11 , in this communication arrangement, can transmit information to configure operational parameters for at least one of the devices or components  49 ,  50  and  51 , in the portable device. The configuration process, preferably, can be in response to monitoring the operating parameters of the respective devices or components  49 ,  50  and  51 , as has been discussed above. This provides additional benefit to a user of the portable device by allowing efficient charging of a battery  21  in the portable device and configuration of parameters of the portable device. Thereby, for example, a user of the portable device can “grab-and-go” remove a fully charged and configured portable device from a charging base unit. This is a significant advantage of the present invention that is not available in prior art charging systems. 
     In a preferred embodiment of the present invention, addressing information is coupled to the transmitted information signals to indicate a source and a destination for a transmission of information signals. Each radio transceiver, for example the radio transceiver  39  on the primary side  12  and the radio transceiver  35  on the secondary side  16 , is associated with a unique address information to uniquely identify the particular radio transceiver in a wireless communication system. Additionally, each device coupled to the particular radio transceiver is also associated with a unique address information to uniquely identify the particular device. The unique address information is coupled to information signals being transmitted to uniquely identify the device that is the intended recipient of the information signals and the device that was the source of the information signals. Addressing schemes for wireless communication are generally well known. For example, the industry protocol specification generally referred to as Bluetooth provides guidance for uniquely addressing devices in a wireless communication system. Therefore, to associate each information signal with at least one device that it represents and to prevent interference between information signals produced by each of the various devices  38 ,  49 ,  50 , and  51 , and information signals delivered by each of the communication controllers  40 ,  42 , and  44 , and by information signals transmitted by each of the radio transceivers  35 ,  39 , certain identification codes (such as addressing information) and frequency hopping techniques could be applied, as would be well known to those of ordinary skill in the art. 
     Additionally, other devices comprising radio transceivers  41 ,  43 , and  45 , with respective antennas  54 ,  56 , and  58 , could be located in the wireless communication system. These devices  41 ,  43 , and  45 , according to a preferred embodiment of the present invention, could also be capable of communication of information signals with the controller  11  and with the communication controllers  40 ,  42 , and  44 . Unique addressing information associated with information signals communicated with each device comprising a radio transceiver  41 ,  43 , and  45 , in accordance with the discussion above, facilitates identifying information signals associated with a source device and with a destination device in the communication system. In an exemplary embodiment of the present invention, the controller  11  may control a charging of the battery  21  of a portable device, and configure devices  49 ,  50 , and  51 , in the portable device, and additionally configure other related devices  41 ,  43 , and  45 . In this way, the user gains the additional benefit of quick configuration of all related devices and of charging of the battery  21 . The convenience of an efficient battery charging process and quick configuration of all related devices provides a user with significant advantages over any prior art charging system. 
     Although specific embodiments of the invention have been disclosed, it will be understood by those having ordinary skill in the art that changes can be made to the specific embodiments without departing from the spirit and scope of the invention. The scope of the invention is not to be restricted, therefore, to the specific embodiments, and it is intended that the appended claims cover any and all such applications, modifications, and embodiments within the scope of the present invention.