We have seen a lot of new technology adopted in smartphones and mobile devices over the last five years or so. But I now think the industry is ready to adopt a technology that has not met industry needs to date: haptics. What is bolstering this optimism are the maturity of piezoelectric actuators and specialized drivers that can now meet the low-power requirement along with a customizable haptic interface.
Leading the charge are TDK Electronics, a subsidiary of Japan-based TDK Corp. and Canada-based Boréas Technologies, Inc. At SID Display Week 2019, the two announced a new cooperation agreement to “accelerate the adoption of piezo haptic solutions in a broad range of applications.” And mobile devices are at the top of the list.
If you look at the mobile device market, it is clear that display performance is already stellar. We have high-density displays with reference-grade image quality. Almost all mobile displays also include a touch interface. In fact, if it doesn’t have touch capabilities, you start to wonder why. Foldable phones are all the rage, offering a new form factor, and, there is a clear trend to eliminate any buttons or holes on the smartphone. Buttonless phones and foldable phones now have a clear opportunity to consider a haptic interface. But is there a need? Is the technology ready?
There already are haptic devices in smartphones today – they provide the vibration that let’s you know you have a message, notification or email waiting for you. That’s fine, but there is a lot more that haptics can offer. For example, users don’t like to use display-based keyboards because they don’t provide any haptic feedback – you can’t touch type and get the tactile feedback similar to a real keyboard.
The new piezoelectric actuators from TDK and the drivers from Boréas can solve this problem. A software layer allows the creation of waveforms that can reproduce the sensation of running your fingers over a keyboard, changing that sensation when you select a key. Think of all the icons that can now have their own “tactile profile” to provide a next generation user interface. Boréas’ SmartClik product exemplifies this functionality. At SID Display Week 2019, Boréas is demonstrating a prototype of a “virtual button” by replacing a physical button on the side of the smartphone with a piezo/driver combination.
And it is not just mobile phones that can benefit from a new haptic interface. Tablets, automotive displays and controls, wearables, gaming consoles, industrial equipment, medical devices and more can all benefit. In cars, for example, the trend is toward an all-glass cockpit with the elimination of dials, gauges and buttons. A touch interface is nice, but you have to look down to see where you are on the display. Haptics can aid in this non-direct-view interaction with the display.
This use case extends to industrial and medical workers who may want to look one way and interact with equipment simultaneously. So why hasn’t the technology been adopted more widely? The short answer it that the trade offs in solution size, power and functionality have not always met the needs for particular applications. Piezoelectric transducers require high voltage, 60-120V typically, to create physical movement in the actuator. The new driver technology from Boréas moves away from the audio-centric designs that have been the approach used in piezo drivers in the past. As a result, the new Boréas driver offers 6X faster response time (<1ms) and 10X lower power consumption compared to existing solutions. This makes it suitable for mobile applications for the first time. And, it comes in a tiny 4 x4 mm QFN package so it can actually fit in mobile devices too.
The second technology advancement is the introduction of TDK’s TDK’s PowerHap™ and PiezoHapt™ families of piezo actuators for haptic feedback. Further, TDK has recently extended its portfolio of PowerHap piezo actuators for haptic feedback with the new miniature 0904H014V060 and 1204H018V060 rectangular actuators. They have dimensions of only 9 x 3.75 x 1.4 mm and 12 x 4 x 1.8 mm, respectively. At the maximum operating voltage of 60 V, the new actuators can accelerate a mass of 100 grams at 3.3 g (pk) or 5 g (pk) with maximum displacements of 15 µm or 27 µm, respectively. A key feature is the low energy consumption of only 0.35 mJ or 0.6 mJ per feedback. In addition to the actuator properties, PowerHap also offers good sensing functionality by using the inverse piezo effect.
The final part for the haptic solution is the software to create the waveforms needed to achieve different tactile sensations. The shape and frequency of the signal can impart a different “feel” while the amplitude can set the intensity or impact that the signal has on the person. High amplitude signals can deliver strong displacement and G forces, providing very positive feedback signals – like a button click. And, this can be done with very low latency, says Boréas.
Other haptic solution like eccentric rotary mass (ERM) or linear resonant actuators (LRA) cannot do custom waveforms, high-density haptic interfaces or force sense, all of which piezo devices can do. This force sense capability is interesting, too, as it runs the piezo in reverse, harvesting mechanical movement to create electric energy. Wouldn’t it be nice to know that as you walk around with your phone in your pocket that you are actually charging the battery? That’s not quite possible today but it gives some insight into the far-reaching features that piezoelectric transducers might someday enable.
The TDK and Boréas cooperation is just the start. TDK has also signed an agreement with Immersion Corp. to take the TDK/Boréas solution to the automotive, industrial and other markets. I can see other partnerships developing to commercialize this new interface to the mobile device segment. In fact, it might even make sense for some sort of a mobile haptic alliance to be formed that can educate product designers and developers on the new haptic technology and help develop the tools and resources that can speed introduction of solutions into the mobile device market.―Authored by Chris Chinnock, Insight Media