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Transmitters use light to charge devices

11 Mar 2015  | Jessica Lipsky

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At the Mobile World Congress, wireless charging company Wi-Charge unveiled a light-based charger targeting home and mobile devices. The device does not aim to replace other wireless charging methods but rather serve as an alternative supporting background charging across long distances.

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Wi-Charge's vision for light-based charging in a home.

The Israeli company developed transmitters and receivers that use laser light to charge a variety of devices. Initially using form factors that fit into a light bulb or wall socket, the transmitters are designed to provide a constant charge while eliminating the unsafe radiation associated with infrared light.

Wi-Charge developed a charging system—called a "distributed resonator"—that creates a high-powered light source with two retroreflective mirrors, which are similar to that of a bicycle reflector. By placing one mirror at the laser/transmitter and another alongside a photovoltaic cell at the receiver or device end, Wi-Charge created a closed loop that doesn't allow for ultra-high energy dissipation into the body.

Distributed resonator

One transmitter can support multiple devices, with the total number of charging devices dependent on battery size. Wi-Charge showed its smart home device first, with a receiver module powering up to 2W and a 2W plug-in transmitter that covers a 15-foot room. A 17mm x 17mm transmitter designed for mobile devices could push 10W while receivers would be capable of 5W. In a demonstration, a Samsung Galaxy S4 was able to charge on a 10-foot table rotating up to 80 degrees.

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"The idea is that your devices will always be charged, never empty," Guy Michrowski, vice president of marketing, told EE Times. "We push the power needed for use of a device, plus extra."

Other form factors the company developed for its chargers include a dongle that can attach to a speaker and an embedded receiver in a phone case. The company's longer-term vision would integrate transmitters into a smart light bulb, CEO Victor Vaisleib said.

"The receiver will be eventually integrated into the device, maybe embedded in front of a phone, or it can go under the glass," Vaisleib told EE Times. "In mobile what you should expect from this technology is between two to three hours from empty to completely full, but that's not because there's a specific limitation. We're not trying to compete with fastest charging method."

While Wi-Charge works to shrink its transmitters to at least 10mm x 10mm and increase its charging distance up to 30ft, the company faces the challenge of entering a wireless charging field that's been dominated by coil-based players. Vaisleib is confident about Wi-Charge's place in the race.

  • You see all those inductive consortia fighting each other for dominance because they understand that no one will include three or four [charging] methods inside devices. There will be one that will win and supplant all devices. It's clear that inductive solutions are a very weak value proposition; they all have a sense that long range power will come.

Still, Wi-Charge hopes to partner with larger OEMs, many of whom are members of several wireless charging consortia, to proliferate their devices and drop the price by using non-proprietary silicon. Currently, transmitters and receivers are made in-house and the estimated cost for a mobile solution is $149.

"We definitely see ourselves using third-party components and working with OEMs to productise this," Michrowski said.

Michrowski expects Wi-Charge to coexist with other wireless charging technologies, serving as a compliment to an overall wireless charging environment supporting multiple use cases.

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