Patent Application
20060061324
1. Technical Field
This invention relates generally to the field of contactless battery chargers for portable devices, and more particularly to a contactless charger with an alignment indicator to facilitate efficient charging.
2. Background Art
Contactless, or inductive, 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 an inductive connection. 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.
Most all contactless chargers charge batteries by induction. Current, passed through a coil, creates a magnetic flux in accordance with Ampere's law. When a second coil is placed in close proximity to such a current-driven coil, the flux couples to the second coil, thereby “inducing” a current in the second coil. Such an induction circuit is illustrated in
Turning now to
One problem that plagues most contactless chargers is aligning the secondary coil with the primary coil so as to couple the most magnetic flux to the secondary, thereby ensuring the most efficient charging process. One prior art solution for aligning the primary coil and secondary coil is to make a charger with a pocket having an encapsulated contactless plug, such that when an electronic device is placed in the pocket, the contactless plug fits within the device and aligns the primary coil with the secondary coil. This is referred to as a “lock and key” solution, in that the encapsulated plug serves as a “key” that fits into a recess in the device, which serves as the “lock”. Such a charger is taught in U.S. Pat. No. 5,952,814, entitled “Induction Charging Apparatus and an Electronic Device”, and is shown generally in
The problem with the lock and key solution is that a unique charger must be specifically designed for each electronic device. Since every electronic device has a unique shape or form factor, manufacturers must make unique chargers to accommodate all of their different products. This specialization of chargers makes the product time consuming to design and expensive to manufacture.
Accordingly, there is a need for an improved, contactless charging system that facilitates alignment of the primary and secondary coils.
A preferred embodiment of the invention is now described in detail. Referring to the drawings, like numbers indicate like parts throughout the views. As used in the description herein and throughout the claims, the following terms take the meanings explicitly associated herein, unless the context clearly dictates otherwise: the meaning of “a,” “an,” and “the” includes plural reference, the meaning of “in” includes “in” and “on.”
Turning now to
The primary 300 includes a wire 304 that is coiled about a core 302. The core 302 is optional, in that some primary windings use air, plastic or other material as a core. However, for maximum efficiency, the core 302 is generally a metal with a high magnetic permeability, like iron. As is known in the art, when current Ip passes through the coil of wire 304, a magnetic field 306 is generated in accordance with Ampere's law. This magnetic field 306 forms a closed loop about the core 302. If a secondary 301 is placed within the field 306, such that the field 306 passes through the coil of secondary wire 305, a secondary current Is is generated. It is the goal of contactless charging to maximize the efficiency of this current-to-magnetic field-to-current conversion.
The conversion is maximized, i.e. is most efficient, when the primary 300 and secondary 301 are aligned such that the magnetic field 306 passes through all of the turns of wire 305 in the secondary. In the exemplary embodiment of
In
Turning now to
The charger 500, shown here in a cutaway drawing, includes a primary coil 502 for transferring power to an electronic device 501 to be used for charging a battery. The primary coil 502 receives power from a power source 506, and may include circuitry, including a primary controller like that shown in
Turning now to
The graphic representation 600 may take many forms. In one embodiment, the graphic representation may be a pictorial representation of the electronic device 501. In another embodiment, the graphic representation 600 may be an outline of the electronic device. Alternatively, the graphic representation may be a pictorial representation of a generic electronic device, an outline of a generic electronic device, a textual description of a preferred electronic device orientation, text or other visual indicators of the electronic device orientation. In the embodiment of
The graphic representation 600 may be disposed upon the charging surface 504 by any of a variety of methods. These methods include painting, silk screening, plating, printing, lithography, etching and vapor deposition. Alternatively, the graphic representation may be molded into the charging surface 504 by an injection molding or other equivalent process. It will be clear to those of ordinary skill in the art having the benefit of this disclosure that the charger 500 of the present invention may be used with a variety of electronic devices, including telephones, two-way radios, computer mice, pagers, personal digital assistants, music players, video players and portable computers. As such, the graphic representation 600 may depict any or a combination of these devices.
Turning now to
To summarize, this invention provides a contactless charger for an electronic device, wherein the charger includes a graphic representation or an image disposed on the charger. The image is indicative of a preferred orientation of the electronic device for efficient, contactless charging. In one embodiment, the image is geometrically similar to the electronic device, and may take the form of outlines, pictures, text, and directional indicators.
The invention may be used with a variety of devices. For example, if the device is a cellular telephone, the image may comprise an outline of the cellular telephone. The contactless, or inductive, charger may include a substantially planar surface, and the image or visual indicator is disposed upon the substantially planar surface such that the visual indicator represents an orientation of an electronic device associated with optimal inductive charging. The visual indicator may be representative of the specific electronic device to be charged, or may be generic in shape so as to make the charger more universal.
While the preferred embodiments of the invention have been illustrated and described, it is clear that the invention is not so limited. Numerous modifications, changes, variations, substitutions, and equivalents will occur to those skilled in the art without departing from the spirit and scope of the present invention as defined by the following claims.
