Apple's interest in wireless charging technology was detailed in a new patent application published this week by the U.S. Patent and Trademark Office and discovered by AppleInsider. Entitled "Wireless Power Utilization in a Local Computing Environment," it describes a system that would rely on "near-field magnetic resonance" to provide power to nearby devices.
Apple's filing notes that transferring power wirelessly has historically been successful only in fairly limited applications. Specifically, the technology requires a power source and receiver located very close to each other.
This method may be acceptable for devices that require a very small amount of electricity. But Apple says this process is not acceptable for devices that require between a few watts to hundreds of watts.
However, Apple noted that electricity can be transferred from a power source to a receiver within a "near field," or a distance a few times larger than both objects involved in the transfer. In most scenarios, this near field would be about a meter large.
"In this way, a realistic and practical approach to wireless transferring useable amounts of power over distances suitable for limited applications can be realized," the filing reads.
By adopting wireless charging technology, Apple could minimize or eliminate what it referred to as "unwieldy" existing chargers that must be plugged into the wall.
Apple's system goes one step further than the near field, and aims to improve efficiency when transferring electricity wirelessly. It would also allow a number of peripheral devices to be charged wirelessly within the near field, thanks to "cooperation" between them.
Apple's charging accessory would be able to provide electricity to a number of devices located within the near field, or "virtual charging area." Low-power devices cited by Apple include a mouse and keyboard.
The power supply transmitter could be a stand-alone device, or it could be embedded in an existing device such as a desktop or notebook computer. The transmitter could also be portable, such as a dongle that could be connected to a legacy device via a port like USB.
Peripheral devices would need to be tuned to the appropriate frequency. This would allow them to receive power from the near-field magnetic resonance (or NFMR) power supply.
"The device being brought into the range of the NFMR power supply can communicate its initial presence using a standard communication protocol such as WiFi or Bluetooth," the application reads. "However, once incorporated into the resonance circuit, the device can use a communication back channel."
Apple's application also describes the use of a "re-resonator" that would allow electricity to be wirelessly shared between multiple accessories. In one example, a Mac desktop may not be able to adequately provide power to a wireless mouse because of an obstacle interfering with the connection between the two devices.
"In this case, (the) keyboard can act as a re-resonator such that a portion of the power delivered to (the) keyboard from the NFMR power supply can be passed on by way of a re-resonator transmission unit," the filing states.
Apple's patent filing for a wireless charging system, published this week by the USPTO, was first filed by the company in November of 2010. The proposed invention is credited to Michael F. Culbert, Brett. C. Bilbrey, David I. Simon, and Peter M. Arnold.