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Release date: Mar. 26, 2021

Thin Wireless Charging Supports the Melding of Cars and Smartphones

Automobiles are currently going through a technological revolution known as CASE (Connected, Autonomous Driving, Sharing & Services, Electrification). Interoperability with smartphones is said to be an essential part of this trend—hence, technologies that enable easy in-vehicle wireless charging are being hotly watched. TDK’s new wireless charging technology, dramatically thinner than conventional solutions, will make it even more convenient to use smartphones in cars.

The Technical Challenges of Wireless Charging, Essential for Smartphone Utilization in Cars

Interoperability between automobiles and smartphones continues to advance. In North America and Europe, cars with display/audio systems that can “mirror” a smartphone’s screen are becoming increasingly popular, where navigation apps and maps are being widely utilized. Furthermore, in recent years, cars equipped with systems that can unlock/lock the doors and start the engine with only a smartphone instead of physical keys—using Near-Field Communication (NFC*1) and the like—have come to market and are attracting attention. Services that link smartphones and cars in this way are referred to as virtual keys, and are expected to boost services such as car-sharing as they eliminate the need for physical keys. According to a study by Yano Research Institute, the global market for cars equipped with virtual keys is expected to grow to 50.3 million units by 2022 (Global Market Trends and Forecasts for Virtual Keys, Yano Research Institute, released July 17, 2019).

With virtual car keys, drivers are identified with their smartphones, which facilitates the collection of a variety of information. This is expected to invigorate what’s called in-vehicle infotainment (IVI), communication systems that provide both information and entertainment. Making phone calls, sending and receiving messages, playing music, and using car navigation functions should become more convenient and enjoyable in the car, it is believed.

Scenes where automobiles and smartphones interoperate

Scenes where automobiles and smartphones interoperate

Amid the progress of interoperability between automobiles and smartphones, the evolution of smartphone charging functions in cars is under focus. Of particular interest is vehicles equipped with wireless charging systems that allow users to charge their phones by simply placing them somwhere in the car, instead of using a cable as in the past. With conventional wireless charging systems, however, the charging unit that transmits power is very bulky, limiting where the unit can be installed in the car. Clearly, there has been a need for much thinner charging units. Adding to the challenge is the need to integrate Near-Field Communication (NFC), a requirement for virtual keys.

A Wireless Charging Pattern Coil Solution for Automobiles One-Fifth the Thickness of Conventional Products

What solves these issues is a wireless charging pattern coil that TDK developed for in-vehicle use. Using proprietary pattern coil technology, the thickness of the coil unit has been reduced dramatically: it’s nearly one-fifth (approximately 0.75 mm) that of conventional products. In the past, no less than three traditional wound-wire coils had to be combined to accommodate the desired charging area, whereas the new pattern coil can cover the entire charging area with a single coil. Thinner, fewer coils mean significantly downsized circuit boards. This will enable wireless charging not only in the center console, but in door pockets, rear seats, and other places that have been difficult to install in the past.

A conventional product and the new wireless charging pattern coil compared

A conventional product and the new wireless charging pattern coil compared

Wireless charging used to require three coils with conventional products; it is now achieved using only one. The successful application of thin film processing to fine pattern fabrication enabled the reduction of thickness down to nearly one-fifth (approximately 0.75 mm) of conventional products.

Example application of wireless charging pattern coil

Example application of wireless charging pattern coil

Today, the center console is the primary location for wireless charging, but as wireless charging pattern coils become thinner, placement options are expected to expand.

Another feature of the wireless charging pattern coil is the integration of a NFC antenna. In the past, mounting a NFC antenna required its own circuit board in addition the wireless charging coil, leading to a problematic increase in the thickness of the charging unit as the components had to be stacked on top of each another. TDK solved this issue by forming the NFC antenna on the same plane as the wireless charging coil, achieving an extremely thin design.

Integrated NFC antenna

Integrated NFC antenna

The NFC antenna is formed on the same plane as the wireless charging coil, integrating the two.

千代憲隆Noritaka Chiyo
Communication Device Business Group
TDK Corporation

This wireless charging pattern coil for automobiles that achieved a thinness one-fifth that of conventional products was developed leveraging ferrite and other magnetic material technology TDK has fostered since the company’s inception, along with thin film processing technology cultivated for HDD heads and other electronic components. Noritaka Chiyo, Subsection Head of the Communication Device Business Group, who is in charge of this product, discussed the future prospects of wireless charging pattern coils.

“As wireless charging of smartphones becomes increasingly important, we hope to help create a world where you don’t have to carry around a charger or mobile battery. Specifically, our goal is to create more places where you can charge any kind of smartphone just by putting it there—inside cars, on tables in cafes or restaurants, at waiting areas in stations or airports, and so on. Because they can easily be installed almost anywhere, we believe thin coils will greatly contribute to that end.”

 

Wireless charging pattern coil

Wireless charging pattern coil

Extremely thin, with NFC functionality added on the same layer, it is a game-changing wireless charging pattern coil.

Terminology

  1. NFC: Near-Field Communication. An international technology standard for short-range wireless data communication. Short-range wireless communication generally refers to technologies that allow data communication with devices by simply holding over them.

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