Researchers at Fujitsu Laboratories have developed a wireless charging system that they say can simultaneously charge a variety of portable gadgets over a distance of several centimeters without the need for cables. The system, which will be detailed at a technical conference in Japan this week, could begin appearing in mobile phones and other products as soon as 2012, the company said.
Wireless charging has been attracting increased interest in the last few years as the number of portable gadgets multiples. Manufacturers suppose that consumers are eager to get rid of the myriad of chargers and associated cables that can clutter up a modern home. Many of the wireless systems developed to date rely on inductive coupling between two coils, a method that works over a very short distance and typically requires gadgets are placed on a charging pad. Inductive systems can also waste a lot of the power consumed.
Fujitsu's system is based on magnetic resonance in which power can be wirelessly sent between two coils that are tuned to resonate at the same frequency. In theory, it can work over a distance of several metres although Fujitsu's tests have been across a gap of about 15 centimetres. At that distance efficiency is about 85 percent, which means the remaining 15 percent of the energy pumped into the coil is lost in the transfer.
These values are linked, efficiency drops off at the cube of the distance, so increasing the range by even a small amount could have a big impact on the efficiency of the system.
As it stands, Fujitsu's system would enable consumers to place compatible devices somewhere near the transmitter, say on a table top placed next to the transmitter coil, to have them charged. Different devices, each requiring different amounts of power, could be charged simultaneously.
Because transfer happens only between coils that are tuned to the same frequency it should be safe for other gadgets, devices, pets and people within the field. But there has been little research in the field, so the systems could generate the same kind of concerns people have over radio emitting devices or power lines.
Fujitsu's system couples a coil with a capacitor in receiving devices. The size of the device determines the size of coil it can accommodate and that in turn affects the capacitance. As part of its research the company has come up with a new algorithm to calculate these values. Such calculations typically used to take 24 hours on a PC but can now be accomplished in about 10 minutes.
The technology will be presented on Tuesday at the 2010 conference of the Institute of Electronics, Information and Communication Engineers (IEICE).