Gary Marshall goes panning in the river of rumour for nuggets of knowledge
Wouldn’t it be great if you didn’t have to find a cable to charge your iPhone, iPad or maybe even your MacBook? Apple’s working on it.
Wireless charging is already widespread – many smartphones use it, and of course the Apple Watch charges wirelessly too – but so far Apple has mainly stuck with cables. There are several reasons for that. One is that wireless charging is currently undergoing a standards war, with three different ones competing against each other. But more importantly, Apple wants to do things a little bit differently – and differently from how it charges the Watch, too.
The Apple Watch charges via inductive charging, also known as tightly coupled wireless charging. That works fairly well, but it requires specific positioning to work. That’s why the Watch charger clunks into the same place every time; if the charger isn’t in the right place, you don’t get any power transfer. A slightly different form of charging, known as resonant charging or loosely coupled charging, enables you to get your power without actually touching the charger. That charger might live inside your desk or inside your walls – this year, wireless charging firm WiTricity demoed resonant wireless chargers that were placed under desks and behind concrete – or it might live inside your next Mac (see our feature on page 75).
The patent to look at is WIPO document WO2011062827, “Wireless Power Utilization in a Local Computing Environment”. It shows an iMac-shaped device with a Near Field Magnetic Resonance (NFMR) power supply wirelessly charging various devices around it. “Typically,” the patent application says, “the distance can be in the order of 1 meter or so”. A US patent the following year added meat to the bones, clearly showing an iMac wirelessly charging an iPod, keyboard and Magic Mouse – with the keyboard rebroadcasting power to compensate for range-killing interference. Apple has clearly been thinking about this for some time. Back in 2005 it filed a patent for wirelessly charging an iPod, again by resonant charging.
It’s exciting, but the Apple Watch provides a major clue that it’s still some way off; if resonant charging was capable of meeting Apple’s standards, it would be in the Watch already.
Resonant charging, also known as loosely coupled charging, enables you to get wireless power without needing your device to touch a charger.