Time division power supply enables flexible wireless charger sheet that can be cut to shape

Technology News |
By Nick Flaherty

Instead of using a flat plate with complete coils, the cuttable, flexible power transfer sheet which charges devices wirelessly and can be molded or even cut with scissors to fit different-shaped surfaces and objects. This allows charging to included in different ways in a wide range of designs, from consumer electronics to the Internet of Things (IoT).

“I really wish to live in a wireless world,” said Ryo Takahashi of the Graduate School of Information Science and Technology at the Unversity. “Imagine homes and offices without tangled cables, and think how useful it could be for emerging fields like robotics. You can do more than just cut this sheet into fun or interesting shapes. The sheet is thin and flexible so you can mold it around curved surfaces such as bags and clothes. Our idea is anyone could transform various surfaces into wireless charging areas.”

The cuttable sheet is not only much thinner than traditional wireless chargers but has a wider usable charging area from the way the coils are designed. These coils are also wired in such a way that provided enough of them remain intact after the sheet is cut to shape, they can still charge a device. The H-tree fractal design allows the sheet to be cut, while a time division power supply prevents magnetic interference between adjacent coils. This time division scheme uses several groups of non-adjacent coils with a controller that selects the group which power is delivered to. This way, as long as power is transmitted to each group in turn, adjacent transmitter coils are never simultaneously activated, avoiding short circuits or industive coupling.

“Currently a 400mm (15.75in) square sheet provides about 2 to 5W of power, enough for a smartphone. But I think we could get this up to tens of watts or enough for a small computer,” said Takahashi. “In just a few years, I would love to see this sheet embedded in furniture, toys, bags and clothes. I hope it makes technology more invisible.”

Kawahara Laboratory

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