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Bench Talk for Design Engineers

Bench Talk

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Bench Talk for Design Engineers | The Official Blog of Mouser Electronics


Haptic Touch – Valuable Feedback or Just a Cheap Buzz? Mirko Bernacchi


Touch technologies have been with us for decades but our experience with them has not always been positive. Often, we’re not sure if the devices we touch have noticed! Even when there’s some visual or audible indication that they’ve registered our intentions, the outcome isn’t always as we expect – false triggering, contact bounce and other interference effects come into play.

 

Haptic feedback, the science of applying tactile sensation and control to computer interfaces, was intended to improve our experience with touch. Just as often, however, haptic feedback has been an irritation rather than a help.

 

Is there light at the end of the tunnel? Recently, a new type of haptic actuator – the piezoelectric module has come to market with a lot of promise. With ultra-fast actuation times and a wide range of vibration frequencies, piezo haptic actuators can create crisp, clean haptic effects that feel helpful instead of annoying. They have even been used to create new, near magical effects, such as allowing us to “feel” buttons on a flat surface.

 

It is very well possible that we’re entering a new era of haptic-driven touch.

 

Multi-touch at the Cost of Feedback

Smartphones and tablets today are so commonplace that it’s easy to forget that they feature some amazing touchscreen technology. The capacitive, multi-touch capable screens of today are leagues beyond the insensitive, single-touch, resistive touchscreens of yesteryear, and even first generation capacitive screens that were just as good as detecting your palm accidentally resting on the screen as the finger that was actually doing the pointing!

 

Today’s capacitive touchscreens have been a huge leap forward in touch technology, but in our hurry to remove physical buttons from our devices in favor of virtual interfaces, we’ve lost something important - tactile feedback.

 

The State of Haptics

Smartphone makers tried to address the loss of tactile feedback in modern capacitive screens by giving us haptic feedback. The use of simple vibrations, used to mimic the feeling of pressing a key, were often ‘buzzy’, ‘laggy’ and, in fact, nothing like the sensation of pressing a button.

 

One of the key obstacles to creating high quality haptics has been the haptic actuators present in many smartphones.

 

Most smartphone and tablets today use either Eccentric Rotating Mass (ERM) or Linear Resonant Actuators (LRA) to vibrate the device for haptic effects. These tiny devices rotate or oscillate to create vibrations on demand. While cost and power effective, these technologies have trouble recreating desired haptic effects smoothly.

 

Piezo-driven Haptics

Enter piezoelectric actuators. "Piezo” actuators come as small disks or rectangular strips, which deform when a voltage is applied across them. They have a very fast startup time of just 5ms or less, a wide operating frequency range and can generate up to twice the vibration strength of traditional actuators making them well suited for larger smartphones as well as tablets.

 

Piezo actuators enable haptic feedback that’s imperceptibly quick and lasts just the right amount of time. With their small, thin profiles, they’re also able to be placed for localized feedback. Attaching directly behind the display in a mobile phone, they can make it so that only the screen vibrates when a button is pressed. This can give much more realistic physical feedback to a button press than the whole device buzzing annoyingly. With multiple piezo actuators placed across various areas of a touchscreen, an even more fine-tuned and localized feedback effect can be created.

 

Because they’re faster to start up, generate effects and stop, piezo haptics are also more power efficient. A piezo device can literally start up, create an effect and stop in the time it takes for an ERM or LRA actuator to spin up.

 

Haptics Done Right

When done properly, haptic feedback is imperceptibly quick and often quite subtle. We shouldn’t feel that a haptic response happened, just a gentle reassurance that the button we pressed was recognized.

 

Bosch NeoSense

Automotive supplier Bosch recently displayed their NeoSense technology at CES 2016. Using ultrasonic waveforms, the NeoSense interface simulates different textures allowing drivers to feel for buttons rather than taking their eyes off the road. Drivers can feel the notches on the volume slider or tuner giving them precise tactile feedback. NeoSense alleviates one of the biggest challenges with automotive touch panels by using advanced haptic technology.

 

The Future of Touch

While early haptic designs were crude and often irritating, the technology has evolved. Piezo-electric actuators in particular represent a remarkable advance in the responsiveness and quality of haptic feedback, which has been demonstrated by Bosch and shown to be able to produce a high quality tactile experience that feels like the real thing. It’s clear that the technology is here today to move past buzzing smartphones and create incredible, tactile touchscreen experiences.

 



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Mirko Bernacchi joined the Italian branch of Mouser Electronics in Assago in 2012 as a Technical Support Specialist. With more than 25 years of experience in electronics, Mirko provides expert technical assistance and support as well as customer service for our Italian office. He worked as a test development engineer at Celestica and Service for Electronic Manufacturing. At IBM he was a Burn-in memory modules test engineer and an Optical transceiver card test engineer, responsible for the installation of new test equipment, production test problem management and supplier interface as well as the introduction of new test routines.


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