TDK Corp showcased a prototype of headphones featuring a wireless power charging function at CEATEC Japan 2011, which took place from Oct 4 to 8, 2011, in Chiba Prefecture, Japan.
For the headphones, the company employed the "magnetic resonance method," which can well cope with the change of a distance between the power transmission coil and power reception coil as well as their displacements.
At CEATEC 2010, which took place in the past year, TDK unveiled its wireless power feeding system based on the magnetic resonance method for the first time. At that time, it had a demonstration of lighting a light bulb. But, this time, the company showed more specific usages of the system.
Though the power transmission coil embedded in the charging stand is vertical to the power reception coil stored in the headphones, electricity can be fed without any problem, the company said. The output power of the system is several watts, and electricity is stored in the lithium polymer battery in the headphones.
To develop the headphones, TDK used a technology called "automatic conditioning circuit."
"It controls electric power so that frequency does not change even when the power transmission and reception coils are dislocated," the company said. "As a result, it becomes possible to efficiently feed electricity.
In addition to the headphones, TDK attached a power reception coil to the bottom of a toy car and embedded three power transmission coils on the course made for the car. The company had this demonstration, expecting that the same system will be used for feeding electricity to electric vehicles (EVs) in the future.