How touch sensing is gaining traction in automotive design
Engineers have been flirting with cap touch (CT) and its potential for automotive applications for a while now.
Most drivers are familiar with how over the last few years, capacitive touch sensing replaced mechanical buttons in infotainment applications.
But a key innovation in how the sensors handle electromagnetic noise is rekindling interest in CT and extending what’s possible for automobiles.
According to analyst firm Markets & Markets, the CT market is estimated to reach $31.79 billion by 2022. The automotive CT portion of this market is one of the primary growth drivers.
Several increasingly popular CT applications include keyless entry for drivers, rear door opening on minivans and hands-free driver assistance monitoring.
We met with ON Semiconductor’s Bob Card recently to discuss emerging CT automotive trends. With more than 30 years in the business and holder of 10 patents, Card’s perspective provides interesting insight into what’s enabling CT technology’s advancement today.
The increasing complexity of automotive systems measuring user interaction – collectively known as automotive Human Machine Interface (HMI) systems – require ever-more responsive sensors paired with more sophisticated aesthetics. To meet these needs, CT sensing is becoming an attractive technology in automotive designs.
ON Semiconductor developed its first family of CT devices in 2012 for a number of industrial applications. Then in 2015, it moved to develop CT devices for the automotive industry and released them in 2016.
Some key challenges ON Semiconductor overcame in CT technology are enabling designers to employ the technology more readily today. First, CT technology had been hampered by electromagnetic radiation (EMC) “noise” common in all modern automobiles.
EMC noise tolerance can really wreak havoc on CT devices, and it’s a growing problem. Think of all the EMC interference possible in today’s sophisticated automobile, from communications systems to charging systems and more.
To overcome this noise issue, today’s best CT technology uses mutual sensing with differential measurements rather than self-sensing. Differential sensing accounts for already-present EMC in the environment to cancel it out while mutual sensing doesn’t.
“That’s really one of the big benefits of this device. It’s got a differential measurement…and that helps mitigate and attenuate a lot of the noise in a noisy environment,” Card said.
This latest development solves for the noise problem, which means engineers have more distance flexibility and configurability in their designs. In addition, the devices are tunable. Being able to finely tune contributes to increased durability. You can adjust CT sensitivity on the fly.
The latest CT sensors are also much more sensitive, which opens up design possibilities for more robust applications able to support more than just the human touch. The sensors also recognize gestures, enabling the driver with a wider range of control options and providing engineers with new ways to please them.
CT sensing is proving to be immensely popular and useful in automobiles and can enable developers to imagine more applications that truly reduce production costs.