Patent Application
20080048609
The features and advantages of the present invention will be discussed in detail in the following description, and in conjunction with the accompanying drawings:
A device for transferring charge from a source to a client storage device 120 (hereinafter referred to as the “client”) is disclosed. The transfer circuitry is such that the source 110 and client 120 may be of different voltages or currents. Charge may be transferred from a higher voltage source 110 to a lower voltage client 120, from a lower voltage source 110 to a higher voltage client 120, or between a source 110 and client 120 of the same voltage. The source 110 may be an AC or a DC current. A preferred embodiment utilizes a custom boost, buck, or boost/buck switching Application Specific Integrated Circuit (“ASIC”) or a micro-controller with associated circuitry to transfer charges at differing voltages.
In a preferred embodiment, charge is transferred to or from external battery 111 via magnetic leads 101 comprising wires 103 with conducting magnetically attaching ends 102. Alternatively, one or more wires 103 may be omitted with the magnetic connection point directly attached to the device 130. In another alternative embodiment, wires 101 may have magnetically attaching ends 102 at both ends of wire 101 rather than being fixedly attached to the device 130 at one end.
The magnetic leads 101 may attach to a variety of batteries, including but not limited to standard AAA, AA, C, or D batteries and lithium or NiMH-based cells, as the vast majority of such batteries are encased with magnetic iron-based materials. Preferably, the circuitry is able to detect the proper voltage for the source 110 and the client 120. In less preferred embodiments, the user may indicate the type of source 110, client 120, or both. Alternatively, some embodiments may be designed for a specific source 110, client 120, or both. Once the source 110 and client 120 are detected or identified, the boost, buck, or boost/buck circuitry is used to step up or step down the voltage from the source 110 to match the client 120.
The magnetic leads 101 may be polarized such that each must be properly aligned with the positive or negative ends of the battery. Alternatively, the configuration of the internal circuitry is such that the device will function properly with either magnetic lead 101 attached to either end of the battery. If the magnetic leads 101 are polarized, they will preferably be marked in some manner, such as with colors or with symbols, to indicate polarity. Such marking may be on the magnetic connectors 102 or at some other point on the wire 103 or device.
The strong magnetic connection between the lead and the source provides other advantages. This connection allows for good current flow because of its low parasitic resistance. The tendency of the magnetic connector to rub on the source connection point also tends to keep the connection clean and maintain a relatively low resistance connection allowing more efficient charge transfer.
These magnets are preferentially but not necessarily plated with a solderable material like gold. The wires could be connected to the magnets with an electrically conductive epoxy, solder or the like. Alternately they may be soldered or crimped to a connector that is plated and that is designed to hold said magnets.
One preferred embodiment would utilize a micro-controller or ASIC that runs at a voltage between 3V to 5V DC. Batteries for portable devices are generally between 1.5V to 3V. This allows for a narrow purpose lower cost charging circuit. The charger 100 would only pull a charge from battery(s) 111 that are lower in voltage than the voltage the charger 100 is running at internally. This enables a simple inductive boost circuit to be employed where the input voltage is always inductively boosted to a higher charge voltage to be used in charging the internal battery 120. Inductive boosting can be accomplished by switching with a transistor a coil connected to the input source to ground and releasing it so that the higher voltage is created and captured on a capacitor through a series diode which is then used for charging the internal battery. Reverse polarity protection is provided by diode. Both ASICs and micro-controllers are capable of the voltage measurement, switching control, and regulation needed to convert input voltages to the needed charge voltage for this kind of switch boost topology.
Another advantage is that the control circuitry can be made to charge slowly which results in both less expensive (lower power rated) electrical parts and more efficient use of the source battery. Alkaline cells for instance have higher overall capacity if they are used at low current draw.
Another preferred embodiment would allow only for voltages that are higher than the running voltage of the charge circuit. In this case the input voltage is chopped and averaged to create a lower voltage. Chopping, or “bucking” as it is often known, can be achieved cheaply by switching the input voltage on and off through a series inductance in order to control the charging current to the system batteries.
In yet another embodiment where an even wider range of input voltage is desired that can be both higher or lower than the desired charge voltage a more sophisticated and somewhat more expensive approach can be taken where the input voltage is boosted if it is lower than the desired charge voltage or chopped or bucked if it is higher. Several Buck/Boost Converter ICs exist on the market that can accomplish this task. However it is likely that the device would already have intelligent control and therefore a micro-controller would already be embedded in the design. A fairly sophisticated buck/boost switching regulator can be realized in the same control design with the addition of the appropriate switching elements and coils. As these magnetic connections can be freely connected in either forward or reverse polarity to the input source it is useful to build in some form of reverse polarity protection either with circuit elements such as a diode block or bridge or FET block or bridge. The block method simply allows power to flow in only the forward direction and blocks power from flowing in the reverse direction. A bridge allows the power to be directed in the proper forward direction regardless of the polarity the battery is connected. Either method protects the charging circuit, but the bridge allows the user to connect the magnets in either polarity and the device can still charge properly.
Referring to
It will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made within the spirit and scope of the invention. An equivalent structure for those shown herein falls within the invention and the claims.
