By now, you know how important haptics are to the smartphone user experience, but there’s still more to the story. We recently had a virtual conversation with the team at Cirrus Logic to get a better understanding of the price constraints that come with premium haptics, what implementation challenges they face as smartphones evolve, and more. Here’s how it went.
Q: How much do good haptics cost?
Performance is not solely down to cost. Other factors, such as placement of the actuator and the mechanics of how the vibration travels through the different materials are important.
Great haptics need to start with the basics of a good actuator. There are several types of actuators found in smartphones, from buzzy low-cost ERMS, to low-cost Z-Axis LRAs, which tend to ring or buzz after a haptic event. Neither of these will provide a good user experience.
Lateral Axis LRAs are becoming more mainstream in higher-end smartphones — these are more expensive, but they’re coming down in cost. An advanced Smart Haptic Driver IC like the ones from Cirrus Logic use an advanced closed loop control. This setup can help lower-priced LRAs perform way better and make great LRAs perform even greater, thus leading to rich, high-definition haptics that premium products demand.
Q: How have haptics changed over the years?
Smartphone haptics have improved in recent years, namely due to the haptic sub-system ushered in by the shift from ERM-style actuators to LRAs. The haptic driver is now a fundamental part of this setup, whereby previously, OEMs used a discrete makeup of dumb external components or utilized the PMIC to drive an actuator.
Some OEMs try to get away without using a dedicated haptic driver, and the haptics suffer. You can see in some teardown reviews where OEMs cut corners to save a bit of money. Largely now, OEMs are looking to use dedicated Smart Haptics Drivers that contain boost, DSP, and memory to store algorithms.
Cirrus Logic’s closed loop architecture allows our haptics to monitor real-time changes to the LRA and automatically adapt the waveform to ensure high-definition effects. This sets Cirrus apart from the rest of the competition and enables sharp, crisp, and consistent haptics, along with more haptic features, all of which are fundamental to the user experience.
Q: How much do good haptics depend on software?
Good haptics are very dependant on software. There are several elements of software that make up good haptics, such as our closed loop control algorithms. The software needs to dynamically adapt the haptic waveforms to the changes in environment and electro-mechanical changes to the LRA, so the user experience is consistent, crisp, and emulates the real feel of using physical buttons.
Software features can also enhance the haptic use cases by analyzing the audio stream and deciding when to trigger a haptic event — we call this “audio to haptics.” We use this when someone plays a game or watches content on their smartphone where on-screen events (like explosions or gunshots) employ haptics to make the viewing experience more immersive.
Finally, there are the software tools, which are used for fine tuning performance and enabling smartphone UX teams to design the haptic effects that they want to achieve in their devices.
Cirrus Logic provides all of these attributes in our haptic products.
Q: What are the biggest challenges of tuning haptics on a phone?
Understanding and characterizing the LRAs is paramount. Every LRA has different attributes, so we use software to determine the electrical characteristics, which ensure that the design of the waveforms are optimal and lead to good performance.
Tuning the haptics LRA can be extremely challenging if you are unable to characterize the electro-mechanical properties of the LRA. Every LRA is unique and has different impedances and optimal resonant frequencies that change over time. Because Cirrus have monitoring ADCs and algorithms that can determine the key properties of the LRA, it means we can tune waveforms specially for that given LRA to maximize performance. That, coupled with real-time closed loop feedback, ensures the performance is always consistent, which is fundamental to UX.
Cirrus have developed an innovative toolchain that simplifies the tuning process and actually automates the LRA characterization, so OEM UX teams can take our tools and define whatever haptic experiences they prefer — the world is their oyster. Cirrus takes care of the complexities and simplifies the overall process for them.
Q: How has the shift to phone materials like glass and aluminum made haptics better or worse?
This is really dependent on the overall mass of the application and the placement of LRAs. Cirrus has a boosted architecture where we can deliver a short, sharp burst into the LRA to increase the drive strength and — using our closed loop control — we can instantly stop the LRA when required. Cirrus also tunes the haptic system as the resonant frequency may change once the LRA is integrated into a system compared to a development platform. You can now see the same Cirrus Logic haptics driver being added into larger applications, such as trackpads in laptops, due to the overall capabilities of our IC.
Q: How has the growing size of today’s smartphones impacted haptic performance?
Phone sizes haven’t really impacted our haptic performance because we can crank out the most performance of any given LRA, and as mentioned, we can deliver LRAs in even bigger applications.
Foldable phones, on the other hand, present a unique challenge because they tend to be bigger and bulkier than typical smartphones. Electro-mechanical properties also change significantly when a phone is opened or closed. Being able to dynamically adapt to these changes is a significant competitive advantage of Cirrus’ closed loop architecture, because we can automatically increase or decrease the drive strength so that a user’s perception of haptic sensations do not change. This enables our haptics to feel consistent, regardless of how a phone is held, or even if it’s folded vs. unfolded.
Learn more about Cirrus Logic
Want to learn even more about premium haptic technology? Our friends at Cirrus Logic are a great place to start. Their tech can be found in some of the most lauded devices for haptic performance from OEMs like Google and Samsung. Check out Cirrus Logic’s website for details.
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