Wireless Charging

Wireless Charging

This is a new tech, I came across in few Lumia phones and iPhone5.

Wireless charging - as the name says, its rightly wireless...

The phone needs to be placed in a dock (Apple products basically) or on a charging pad (for Lumias and Samsungs).

The principle here is 'induction charging' - wherein two induction coils (say A & B), current is passed through one coil, and by an emf creation there would be a current flow in the other coil.

Likewise, here the phone would have an A coil, joined with the battery terminals. The pad/dock have the B coil. Now place your phone in the pad/dock - switch on the pad/dock - there's A & B coil creating induction that charges the battery.
 
Though wireless, you would still require the pad/dock to be wired.
In terms of efficiency, this wireless charging looses to its typical wired counterpart - there is more charging time.
Using the phone while charging is impossible in this new tech, since the gap between phone and pad/dock matters. May be, users would need to evolve by using it from the pad/dock straightaway, similar to the way people started texting even on a walk ;)
 
Wireless charging had been a vogue in most of the premium smartphones since September 2012. Yet, right from the 90's this concept was used in electric-toothbrush, automobile battery charging, laptops...
Unlike the standardized wired charging tech (micro USB), wireless charging isn't standardized - and that's eventually a temporary setback.
There are 3 competitive standards here, each having their own design perspective on the induction principle, with pros & cons.

1. Qi standard (pronounced as 'chee' - of Wireless Power Consortium, WPA)
2. PMA (Power Matters Alliance, of Procter & Gamble)
3. A4WC (Alliance for Wireless Charging)

Though Qi standard is been widely used with leading number of members and products, A4WC has the leading chipset vendor Qualcomm. Samsung signed up with all these 3 standards. So as of October 2013, confusion and competition persists in the standardization of Wireless Charging.
 
Technically about these standards - they all revolve upon the maneuvering of emf creation, magnetic induction, types of coil, range of emf, efficiency of charging, space between device & pad/dock etc.,
To be brief, 

the Qi standard is high in efficiency but low in range and A4WC is vice-verse. Simply, the Qi standard charges your phone quickly; but it requires the space between your phone and pad/dock to be in centimeters, rather what the A4WC requires in inches. 

I'm not sure about WMA's such impact.
 
Ironically, induction-charging could be an apt name here. Still its wire-free; a main breakthrough to reduce the phone size without the charging port.
Yet another interesting innovation!