Thursday, September 20, 2012

Qi wireless charging: what is it and how does it work in Nokia's Lumia 920?


With the announcement of integrated wireless charging in theLumia 920, Nokia hopes it will be a significant part of the proposition to turn heads from Android and iPhone. But unlike previous examples like the Palm Pre's Touchstone charger, Nokia has joined HTC, Sony, Samsung and others by adopting "Qi", a proprietary interface standard created by the Wireless Power Consortium.
Qi, pronounced "chee", comes from the Chinese symbol meaning energy flow and is designed to provide energy to devices through magnetic induction. This is a similar solution to the system that charges electric toothbrushes. (It's also a valuable and legal two-letter word in Scrabble.)
In simple terms, the base station includes an induction coil that creates an alternating electromagnetic field. Meanwhile, a similar coil within the device is able to pick up this field, convert the energy into current and use it to charge the battery.
After defining the low power (five watts) specification in 2009, the spec was expanded to medium power in 2011, enabling the projection of up to 150 watts -- a significant leap and one Nokia publicly welcomed last month. In reality, the former wattage should be more than enough for a smartphone but it's worth bearing in mind in relation to speculation that a Nokia Lumia tablet could be on the cards some day.
It's also positive news for phone users in that they will be able to charge the device on base stations previously released for other projects -- with the Consortium conveniently announcing that there are now 110 certified examples from 124 members. As Virgin Atlantic and US coffee franchise Coffee Bean and Tea Leaf will be supplying charging stations for public use, these are all positive signs of momentum behind the standard.
Considering the technology has been around for so long, maybe the power of a unified spec among leading manufacturers could provide the tipping point for its mainstream adoption. It wouldn't be the first time in the world of tech after all.


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