Multiple devices can be charged at the same time.
Multiple devices can be charged at the same time.
[Click to enlarge image]
A prototype of the wireless charger designed for the iPhone and the iPad
A prototype of the wireless charger designed for the iPhone and the iPad
[Click to enlarge image]

Murata Manufacturing Co Ltd announced that it has developed the "LXWS series," a wireless power feeding system based on "electric field coupling" technology.

The system has already been employed for a toy that will be released for the Christmas season of 2010, Murata said. The company plans to start volume production of the module of the system in the fall of 2010.

The electric field coupling technology is used to transmit electric power by using electric field resonance generated between electrodes that are installed in a power transmitting device and a power receiving device. Though the power transmitting device and the power receiving device have to be in contact with each other, the system does not require accurate positioning in the horizontal direction. Any conductive material can be used as an electrode.

This time, Murata showcased a battery charging mat made by using copper (Cu) foil as well as a battery charger that is designed for the iPhone and the iPad and uses ITO (indium tin oxide) as a transparent electrode material.

The latest module of the system has an output of 3W and is targeted at mobile phones, portable music players, compact digital cameras, etc. Murata plans to start volume production of a module with an output of 10W in fiscal 2011. Furthermore, the company aims to develop a module with an output of 50W for notebook PCs, etc and start mass-producing it in 2014.

The elementary technology for power transmission using electric field coupling was introduced from TMMS Co Ltd, which supports technology development. Then, the efficiency was improved by adding Murata's circuit design technologies and making improvements to the electrode structure.

The transmission efficiency between a power transmitting device and a power receiving device is 90% or more. When a power supply unit, a rectifier circuit and so forth are included, the total efficiency is 70-80%.

Murata has been developing a wireless power feeding system based on electromagnetic induction technology in collaboration with Seiko Epson Corp since 2007 (See related article). And the company started developing a wireless power feeding system based on electric field coupling technology in 2008.

The new system was employed for the toy seemingly because the system enables to easily charge a device just by placing it on the mat and does not require accurate positioning.