Electricity: battery or capacitor charging or discharging – Cell or battery charger structure – Charger inductively coupled to cell or battery
Reexamination Certificate
2000-03-20
2001-02-06
Wong, Peter S. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Cell or battery charger structure
Charger inductively coupled to cell or battery
Reexamination Certificate
active
06184651
ABSTRACT:
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 de
Borras Jaime A.
Fernandez Jose M.
Garrett Scott M.
Motorola Inc.
Tibbits Pia
Wong Peter S.
LandOfFree
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