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`FEATURE
`
`Wireless charging explained: What is it and how
`does it work?
`
`Wireless charging technology has been around for more than 100 years, but its inclusion
`in devices such as Apple's new iPhone line has given it new life. Here's how it works, and
`why it could soon show up in everything from homes to robots.
`
`By Lucas Mearian
`Senior Reporter, Computerworld | MAR 28, 2018 4:52 AM PDT
`
`With Apple embracing the Qi standard in the iPhone X and 8/8+, wireless charging is finally
`becoming more mainstream. But there's an ongoing debate about what it does to smartphone
`battery life.
`
`Closed captioning available on our YouTube channel
`
`TABLE OF CONTENTS
`
`Wireless charging has been around since the late 19th century, when
`
`How wireless charging
`works
`
`The wireless charging
`standards battle
`
`AirFuel focuses
`on electromagnetic
`resonant and RF
`
`WiTricity and wireless
`charging in vehicles
`
`Wireless charging over
`distance
`
`SHOW MORE
`
`!
`
`electricity pioneer Nikola Tesla demonstrated magnetic resonant coupling
`
`– the ability to transmit electricity through the air by creating a magnetic
`
`field between two circuits, a transmitter and a receiver.
`
`But for about 100 years it was a technology without many practical
`
`applications, except, perhaps, for a few electric toothbrush models.
`
`Today, there are nearly a half dozen wireless charging technologies in use,
`
`all aimed at cutting cables to everything from smartphones and laptops to
`
`kitchen appliances and cars.
`
`[ Further reading: Is wireless charging bad for your smartphone? ]
`
`Wireless charging is making inroads in the healthcare, automotive and
`
`manufacturing industries because it offers the promise of increased
`
`mobility and advances that could allow tiny internet of things (IoT) devices
`
`to get power many feet away from a charger.
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`The wireless charging circuit board used for Ossia's Cota RF technology, which can send
`power over distances greater than 15 feet.
`
`Ossia
`
`The most popular wireless technologies now in use rely on an
`
`electromagnetic field between a two copper coils, which greatly limits the
`
`distance between a device and a charging pad. That's the type of charging
`
`Apple has incorporated into the iPhone 8 and the iPhone X.
`
`How wireless charging works
`Broadly speaking, there are three types of wireless charging, according to
`
`David Green, a research manager with IHS Markit. There are charging pads
`
`that use tightly-coupled electromagnetic inductive or non-radiative
`
`charging; charging bowls or through-surface type chargers that use
`
`loosely-coupled or radiative electromagnetic resonant charging that can
`
`transmit a charge a few centimeters; and uncoupled radio frequency (RF)
`
`wireless charging that allows a trickle charging capability at distances of
`
`many feet.
`
`Both tightly coupled inductive and loosely-coupled resonant charging
`
`operate on the same principle of physics: a time-varying magnetic field
`
`induces a current in a closed loop of wire.
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`Ikea's wireless charger line-up, which includes a pad that's capable of charging three
`devices at once (center).
`
`Ikea
`
`It works like this: A magnetic loop antenna (copper coil) is used to create
`
`an oscillating magnetic field, which can create a current in one or more
`
`receiver antennas. If the appropriate capacitance is added so that the
`
`loops resonate at the same frequency, the amount of induced current in
`
`the receivers increases. This is resonant inductive charging or magnetic
`
`resonance; it enables power transmission at greater distances between
`
`transmitter and receiver and increases efficiency. Coil size also affects the
`
`distance of power transfer. The bigger the coil, or the more coils there are,
`
`the greater the distance a charge can travel.
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`In the case of smartphone wireless charging pads, for example, the copper
`
`coils are only a few inches in diameter, severely limiting the distance over
`
`which power can travel efficiently.
`
`But when the coils are larger, more energy can be transferred wirelessly.
`
`That's the tactic WiTricity, a company formed from research at MIT a
`
`decade ago, has helped pioneer. It licenses loosely-coupled resonant
`
`technology for everything from automobiles and wind turbines to
`
`robotics.
`
`In 2007, MIT physics professor Marin Soljačić proved he could transfer
`electricity at a distance of two meters; at the time, the power transfer was
`
`only 40% efficient at that distance, meaning 60% of the power was lost in
`translation. Soljačić started WiTricity later that year to commercialize the
`technology, and its power-transfer efficiency has greatly increased since
`
`then.
`
`In WiTricity's car charging system, large copper coils – over 25
`
`centimeters in diameter for the receivers – allow for efficient power
`
`transfer over distances up to 25 centimeters. The use of resonance
`
`enables high levels of power to be transmitted (up to 11kW) and high
`
`efficiency (greater than 92% end-to-end), according to WiTricity CTO
`
`Morris Kesler. WiTricity also adds capacitors to the conducting loop, which
`
`boosts the amount of energy that can be captured and used to charge a
`
`battery.
`
`The system isn't just for cars: Last year, Japan-based robotics
`manufacturer Daihen Corp. began shipping a wireless power transfer
`system based on WiTricity's technology for automatic guided vehicles
`
`(AGVs). AGVs equipped with Daihen's D-Broad wireless charging system
`
`can simply pull up to a charging area to power up and then go about their
`
`warehouse duties.
`
`While charging at a distance has big potential, the public face of wireless
`
`charging has until now remained with charging pads.
`
`IHS Markit
`
`"In terms of progress and industry readiness, charging pads have been
`
`shipping in volume since 2015; charging bowls/through-surface type are
`
`really just launching this year; and charging across a room is probably still
`
`at least a year away from commercial high-volume reality–- although the
`
`new Energous products show this method working over very short range
`
`right now, e.g., a couple of centimeters," Green said.
`
`Just over 200 million wireless charging-enabled devices shipped in 2016,
`
`with almost all of them using some form of inductive (charging pad) type
`
`design.
`
`In September, Apple finally chose a side after lagging behind other
`
`handset manufacturers for years by embracing WPC's Qi standard, the
`
`same that Samsung and other Android smartphone makers have been
`
`using for at least two years.
`
`The first class of mobile device wireless chargers emerged a six or so years
`
`ago; they used tightly coupled or inductive charging, which requires users
`
`to place a smartphone in an exact position on a pad for it to charge.
`
`Show notifications
`
`"In my mind, lining it up exactly to charge doesn't save you a lot of effort
`
`from just plugging it in," said Benjamin Freas, principal analyst for Navigant
`
`Research.
`
`While early adopters and techies bought into inductive charging, others
`
`did not, Freas said.
`
`Belkin's BoosUp wireless charging pad is similar to others in that it contains a copper
`transmitter charging, a chipset to control the power delivered to a device, and foreign
`object detection technoogy to ensure objects that shouldn't recieve a charge don't.
`
`Belkin/IDG
`
`In September 2012, the Nokia 920 became the first commercially available
`
`smart phone to offer built-in wireless charging capabilities based on the
`
`Qi specification.
`
`The wireless charging standards battle
`For several years, there were three competing wireless charging standards
`
`groups focused on inductive and resonance charging specifications: The
`
`Alliance for Wireless Power (A4WP), the Power Matters Alliance (PMA) and
`
`the Wireless Power Consortium (WPC). The latter's 296-member roster
`
`includes Apple, Google, Verizon and a veritable who's who of electronics
`
`manufacturers.
`
`The WPC created the most popular of the wireless charging standards –
`
`Qi (pronounced "chee") – which enables inductive or pad-style charging
`
`and short-distance (1.5cm or less) electromagnetic resonant inductive
`
`charging. The Qi standard is being used by Apple.
`
`The Apple Watch, launched in 2015, uses a inductive wireless charging cable, which still
`requires the device to be tethered to a cord.
`
`Apple
`
`The PMA and its Powermat inductive charging specification found success
`
`by piloting its wireless charging technology in coffee shops and airports.
`
`Starbucks, for example, began rolling out wireless charging pads in 2014.
`
`With competing standards, support for mobile devices remained
`
`fragmented, with most mobile devices needing an adaptive case to enable
`
`a wireless charge.
`
`In 2015, the A4WP and the PMA decided to band together to form the
`
`AirFuel Alliance, which now has 110 members, including include Dell,
`
`Duracell, Samsung and Qualcomm.
`
`In 2014, Starbucks announced it would roll out wireless charging based on the Powermat
`specification for its customers in the U.S. at nearly 8,000 coffee shops.
`
`PMA/Starbucks
`
`As part of the AirFuel Alliance, Duracell Powermat claims it has more than
`
`1,500 charging spots in the U.S., and through Powermat's partnership
`
`PowerKiss, 1,000 charging spots in European airports, hotels and cafes.
`
`AirFuel has also announced wireless charging at some McDonald's
`
`restaurants. That, according to Freas, is one way wireless charging could
`
`see wider adoption.
`
`AirFuel focuses on electromagnetic resonant
`and RF
`AirFuel has focused on two charging technologies: electromagnetic
`
`resonant and radio frequency, which offers the ability to move around a
`
`space and still have your mobile device charge.
`
`"We've seen clear market indicators that resonant and RF are the way to
`
`go. Both technologies offer distinct advantages in terms of spatial
`
`freedom, ease of use, and ease of installation – big factors in creating
`
`market value and customer satisfaction," said AirFuel spokesperson Sharen
`
`Santoski. "And we believe resonant is the best technology to enable
`
`widespread public infrastructure deployment in the near term."
`
`As a result, Santoski said, a growing number of coffee shops, restaurants
`
`and airport have deployed resonant-based wireless charging
`
`stations. "Taiwan is investing heavily, as is China," Santoski said.
`
`AirFuel recently announced a project with the Taoyuan Airport Metro,
`
`which is putting Resonant charging in its trains and stations. And furniture
`
`maker Order Furniture has created a new line of Resonant-enabled
`
`furniture.
`
`"If in every restaurant and coffee shop you have it, then people will be
`
`more likely to use it and get a pad to charge at home," Freas said.
`
`Most of these projects are still just pilot programs, Freas said, adding that
`
`consumers and businesses are less likely to want tightly coupled charging
`
`and more likely to opt for loosely coupled resonant charging That's
`
`because loosely coupled charging provides more spatial freedom – the
`
`ability to simply drop a phone, tablet or laptop on a desktop and have it
`
`charge.
`
`WiTricity and wireless charging in vehicles
`In July, Dell released a Latitude laptop that incorporates resonant wireless
`
`charging from WiTricity, a Watertown, Mass.-based company that licenses
`
`technology originally developed at the Massachusetts Institute of
`
`Technology (MIT). The Dell wireless charger offers up to 30W of charging
`
`power, so a Latitude laptop will charge at the same rate as it were plugged
`
`into a wall outlet.
`
`Dell's new Latitude 7285 2-in-1 laptop and wireless charging pad.
`
`WiTricity
`
`But WiTricity's main focus is the auto industry. The company, which is part
`
`of the AirFuel Alliance, expects a number of electric car manufacturers to
`
`announce wireless charging for their vehicles, according to WiTricity CEO
`
`Alex Gruzen.
`
`The company's electromagnetic resonant technology allows power to
`
`transfer at distances of up to about nine inches away from a charging pad.
`
`That would allow electric cars to charge just by parking on top of a large
`
`charging pad.
`
`For example, Mercedes-Benz this year will roll out S550e plug-in hybrid
`
`sedans with the ability to use WiTricity's technology; the S550e can simply
`
`park over a pad and they begin charging even more efficiently than if it
`
`were plugged in.
`
`Nearly 50 car models now offer Qi-based wireless charging in their cabins.
`
`Wireless Power Constortium
`
`The electric vehicle application is tailor-made for electromagnetic
`
`resonant charging, Kesler said. That's because a vehicle doesn't need a
`
`charging cable, and the wireless charging pad delivers electricity more
`
`efficiently than a cable. (Wired charging systems use electronics to
`
`convert AC to DC and regulate the flow of power, reducing efficiency to
`
`about 86%, Kesler said.)
`
`"Our wireless charging can be 93% efficient from end to end – from the
`
`wall to what's being delivered to the battery," Kesler said.
`
`Wireless charging over distance
`This month, Apple surprised some industry watchers by purchasing
`
`PowerByProxi, a New Zealand-based company developing loosely-
`
`coupled resonant charging technology that's also based on the Qi
`
`specification.
`
`PowerbyProxi was founded in 2007 by entrepreneur Fady Mishriki as a
`
`spin-out from the University of Auckland. PowerByProxi has showcased
`
`charging boxes and bowls into which multiple devices can be placed and
`
`charged at the same time.
`
`The Aukland-based company got its start selling large-scale systems for
`
`the construction, telecommunications, defense and agriculture
`
`industries. One such product is a wireless control system for wind
`
`turbines.
`
`PowerByProxi, a member of the WPC's Steering Committee, has also
`
`miniaturized its technology and placed it into AA rechargeable batteries,
`
`eliminating the need to embed the technology directly into devices. The
`
`wireless technology takes up about 10% of the AA battery height.
`
`Charge-in-a-box: Power By Proxi shows locatio…
`
`Watch on
`
`Apple could use PowerByProxi's technology to expand its use fo wireless
`
`charging beyond just smartphones, using it, for instance, to charge TV
`
`remote controls, computer peripherals, or any number of devices that
`
`require batteries.
`
`While the most visible use of wireless charging technology has been in
`
`Watch later
`
`Share
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`Apple v. GUI Global Products
`IPR2021-00471 GUI Ex. 2005
`Page 1
`
`

`

`While the most visible use of wireless charging technology has been in
`
`mobile device charging pads, the technology is also making inroads into
`
`everything from warehouse robots to tiny IoT devices that otherwise
`
`would need to be wired or powered by replaceable batteries.
`
`Related: Mobile Emerging Technology Internet of Things Small and Medium Business
`
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