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EETE JAN 2014

Design-free RF-based wireless charging redefines user experience By Julien Happich Altho ugh it was established in July 2010, funded by private investors, Israeli startup Humavox has been operating pretty much under the radar until now, busy filing patents and working on the first prototypes of its RF-based charging technology. When interviewed by EE Times Europe, Omri Lachman, co-founder and CEO of Humavox put the emphasis on natural user experience, noting that all existing inductive or magnetic coupling wireless charging mats or surfaces (when the electronics is directly embedded into furniture) require the end-user to place their devices “correctly”, which can be a bit tricky or frustrating if the device does not charge properly. More conventional chargers require wires and connectors to be plugged into the power outlets and the devices. By using well-tuned RF power transmission within a confined environment (i.e a box of any shape able to receive the devices to be charged), Humavox sees many natural opportunities for end-users to recharge their wearable devices, especially as the number of these devices increases and they become smaller. Lachman didn’t want to give away too much about his newly launched Eterna technology platform, consisting of a Nest station (essentially a confined volume with at least one integrated antenna, that acts as the power station for the smart electronics devices it receives and ThunderLink, the company’s wireless charging IP to be integrated into the smart devices (at PCBlevel or as a full ASIC). “To make the charging experience more natural, without asking users to learn yet another procedure, we could implement the Nest charging enclosure in many convenient storage places, such as a cabinet drawer at home, a glove-compartment in a car, a hotel-safe, a seat receptacle in airplanes”, explained Lachman. “Recharging your devices could be as simple as dropping them into a box.” “Essentially, you could refer to the Nest station as a Faraday cage enclosing an RF cavity resonator”, said Lachman when pressed for more technical details. “The RF frequency we use depends on the size of the Nest, it can range from 1MHz for the larger volumes to between 2.4 and 5.6GHz for smaller implementations” he added. With its ThunderLink circuitry, the company is able to precisely tune the RF frequency in the cavity to create narrow hot spots and focus the RF power onto the receiving antennas of the devices to be recharged. The RF signal picked up by the antennas is then rectified to the appropriate DC currents for charging each of the devices’ batteries. The Nest allows multiple devices to charge simultaneously, while constantly monitoring and adjusting the charging process for ultimate compliance with the device’s power requirements. Humavox’ proposed green wireless charging logo. By confining the charging procedure to a box, Humavox claims to achieve a wireless power transfer efficiency of 90%, from the enclosure to the device to be recharged. The company also stays clear of regulations on transmitted RF power in free space, with no limitations on power output, so the Nest could charge anything from tiny hearing aids to smart watches, wearable fitness or health monitoring devices or even more power hungry mobile phones and tablets. The key benefit again is that the devices can be stored in any order and orientation into the Nest, which itself could take any shape. The Nest station was intentionally crafted to be a design-free solution, hence it has no predefined industrial design. To illustrate this, Lachman mentioned an interesting automotive application, where difficult to access sensors had to be powered remotely, in the car engine. Humavox was able to use the engine block as the Nest station and tune the transmitted RF power to precisely address the sensor’s need, in the 200 to 400MHz range. The company is not planning to sell chips, but will license its technology as IP for others to integrate, alongside other charging technologies. It is already working with OEMs and expects Eterna-enabled products to reach market by 2015. An implementation of the Nest charger, though less versatile, could be to convert expensive consumer electronics’ cases into a natural place to recharge the devices (here a conceptual realization for Google Glasses). 14 Electronic Engineering Times Europe January 2014 www.electronics-eetimes.com


EETE JAN 2014
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