A patent granted this week to Apple could one day let users of the company's devices charge them without cables and without the need to place them on charge pads.
US patent 8,796,885, filed on 20 April 2012 and granted by the US Patent and Trademark Office on Tuesday, describes a way of using wireless near-field magnetic resonance (NFMR) to transmit power in a computing environment.
The filing says under the system an NFMR power supply inside, say, a computer could charge any number of suitably configured devices wirelessly at a distance of up to about one metre.
"In this way, a charging region can be formed around the computer in which the peripheral device (or any other appropriately configured device) can wirelessly receive useful amounts of power from the power supply," the filing said.
However, a number of issues could affect the effectiveness of the charging: "Such factors can include, for example, the addition of other devices... that require power from the NFMR power supply, [and] obstacles interfering with the direct power channel".
Much of the patent description covers computer systems where the peripherals, such as the mouse and keyboard, are powered wirelessly from the NFMR power supply housed in the main unit.
The peripherals would each contain what Apple describes as "small form factor wireless power units...sized along the lines of a standard AAA battery".
"It should be noted however, that since small form factor wireless power units... can be of any size and shape, it is contemplated that any battery of any size or configuration can be replaced by small form factor power units."
As well as being incorporated into a desktop, the NFMR power supply could also be built into a laptop or tablet, the filing said, but it could also take other shapes.
"The NFMR power supply can take the form of a portable type unit such as a dongle that can be connected to a legacy device such as a desktop computer, thereby providing the ability to retrofit devices.
"In still other embodiments, housing or a portion of a housing used to enclose the NFMR power source can act to extend a useful range of the NFMR power supply."
Existing smartphone wireless-charging stations such as the Powermat require the device to be in contact with the unit and use inductive charging as opposed to the magnetic resonance set out in Apple's patent.
A number of companies are working on wireless charging over larger distances, including Energous Corporation, which says its WattUp technology can charge devices wirelessly at ranges of about four metres.