MEMS pressure sensors solve new pain points in human-machine interface

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MEMS pressure sensors solve new pain points in human-machine interface [Copy link]

How big is the imagination space for pressure sensing?

Will said that MEMS pressure sensors are a new interactive method compared to traditional touch. Intuitively speaking, "touch" is an action, and "pressure" is also an action. When a finger clicks on an APP on the phone screen, the brain will get the expectation of "opening".

At the same time, when you press an object, your brain will expect different results based on the different forces applied to the surface. This is what pressure sensors are designed to do - accurately determine the force applied to the object and enable the device to fulfill the brain's expectations.

Compared with the two-dimensional capacitive sensing solution with only XY axis, combining pressure sensor with capacitive sensor can increase the data interaction of Z axis (vertical direction), thus bringing more possibilities for HMI applications. In addition, because the data volume of Z axis pressure is richer,

It not only realizes a simple on/off operation, but also transmits more information through different pressure values.

At the same time, another way is to deploy multiple pressure sensors and cooperate with corresponding algorithms to achieve XYZ three-dimensional recognition only with pressure sensors. This technology can theoretically adapt to a variety of environmental challenges including metal, thick gloves, and water operations.

Theoretically, in any scenario where mechanical buttons or capacitive touch switches are used, you can try to use pressure sensors as replacements, which has many advantages such as no need for punching, no accidental touches, and enhanced waterproofness.

However, Qorvo’s ambition for HMI is not just to be a “button replacement”, but has a broader scope of imagination.

A variety of pressure sensor technologies to meet different applications

Pressure sensitivity enhances the operating experience of gaming phones

If pressure sensors want to replace capacitors or other sensors, the most important thing is to find the application pain points. Pressure sensors first appeared on iPhone 6s and implemented the 3D Touch function (Peek and Pop).

However, this feature lacks enough killer use cases, so it has not been widely favored by users and developers. A few years later, Apple decisively replaced 3D Touch with Haptic Touch, using software to implement similar functions, thereby saving costs and power consumption. The same is true for the Android ecosystem.

However, with the segmentation of the mobile phone market, including the emergence of new formats such as gaming phones and folding screens, Qorvo has seen new opportunities and has successfully introduced them into products including Black Shark, Meizu, and iQoo. For example, in Black Shark, by combining pressure sensors and Black Shark's dedicated setting software,

The dual-zone screen pressure-sensitive touch operation adds more differentiation to the game. For example, in MOBA games, you can instantly add blood and change clothes through the pressure-sensitive function when moving and attacking. In FPS games, you can press and shoot when moving and aiming, and press and lie down instantly when walking and shooting, etc.

In racing games, you can flexibly control the accelerator and brake force across the entire screen. A series of examples show that pressure sensors facilitate operation and enhance the game's striking experience.

In addition to games, Black Shark has also expanded the pressure sensor to pressure-sensitive navigation in system applications. Users can press the screen anywhere to pop up the operation navigation, turning the phone into a one-handed operation artifact.

Will added: "Pressure sensing can achieve more accurate operations without being triggered by mistake. This demand will increase with the emergence of full-screen, foldable screens, gaming phones, etc."

According to reports, there are currently two solutions for implementing pressure sensing. One is in the form of a module, using an MCU to process pressure sensing signals. This module is composed of multiple FPCs, so multiple large holes must be opened in the middle frame of the mobile phone, and the durability and yield of the FPC have some drawbacks.

Qorvo's solution is to use a single chip that integrates sensors and analog front-ends, which can communicate directly with the CPU without an MCU. It has a smaller opening, has relatively less impact on ruggedness and heat dissipation, and is easier to install.

According to Will, Qorvo's current solution only requires two chips to achieve double-finger pressure detection on the upper and lower screens.

For pressure sensor applications without side buttons, Qorvo will provide sensor fusion solutions, including pressure sensors, infrared sensors, ultrasonic sensors, and single-chip solutions implemented by analog front-ends without buttons, in which IR plays a role in positioning.

In this way, pressure sensing can be easily achieved with only one sensor, thereby simplifying the design and avoiding accidental touch operations.

Importantly, Qorvo can provide a complete hardware solution as well as software algorithms, thus removing design barriers and allowing customers to focus more on differentiating their applications using pressure sensors.

TWS fully reflects the difference in pressure sensitivity

Although Apple did not choose pressure sensors in later iPhones, it fully embraced pressure sensors in TWS. The main pain point of HMI for TWS applications is false touches of capacitive sensors, including hair, rain, sweat, grease, etc., which can cause false touches and affect the experience.

In addition, for those that use MEMS acceleration sensors to operate by tapping, the actual experience is not as direct as that of pressure sensors. It is understood that the pressure sensors currently used in TWS have been gradually introduced from the mid-to-high-end market to the mid-end market.

Will said that for TWS applications, Qorvo's products are more suitable for this scenario due to their advantages such as single chip, small size, support for digital output, and simple modules. And as more cases are introduced in the market, customers are becoming more and more confident.

Other wearable devices

In addition to TWS, pressure sensors also have broad development prospects in watches, bracelets and even AR/VR devices. Taking smart watches as an example, Google-Fitbit adopted Qorvo's solution to replace the mechanical switches, knobs or sliders in the watch, making the watch more waterproof.

However, Will also mentioned that there are still many debates about whether to cancel mechanical buttons for smart watches, such as the aesthetic perception of watches or functions such as heart rate measurement, which cannot replace mechanical buttons. But at least for capacitive touch solutions in wearable devices,

The pressure sensor is fully capable of the task and supports underwater/humid environments, making it a better experience.

Improved experience of productivity tools

Pressure sensors are also very suitable for productivity tools. Taking Apple as an example, its notebooks have always adopted Force Touch technology and have been widely recognized by customers. Now this technology is being favored by more brands.

In addition, for tablets and handwriting tablets used in productivity, pressure sensors can simulate functions such as "paintbrushes" by virtue of their high-order and delicate Z-axis response.

Automobiles will be another flashpoint

Qorvo also expressed its attention to the automotive market. As the only pressure sensor supplier that has passed automotive-grade certification, its products have been widely used in models including Tesla, Geely, and Chery, and have passed PPAP certification from three Tier 1 suppliers including Valeo, Yanfeng, and Joyson.

Its application occasions include car doors, multi-function steering wheels, central control, etc., among which Tesla alone uses more than 10 pressure sensors. Especially with the deepening of the concept of "putting wheels on mobile phones", we see that inside the car cab,

Whether it is the instrument panel, the main control screen, the central control panel or even the co-pilot screen, they are all developing in the direction of more and larger ones. Mechanical buttons and knobs are gradually being replaced by virtual buttons on the LCD screen.

With this change, the car cockpit has changed from being surrounded by mechanical buttons, knobs and indicator lights like the cockpit of an airplane in the last century to being presented in a more friendly, flexible and simpler way with screens everywhere. This has brought demands for automotive HMI far exceeding those of the mobile phone market, and also given pressure sensors more room to display their capabilities.

High quality is the basis of experience

Last but not least, product reliability is the foundation of all user experience. Not to mention being unable to accurately command a car on a fast highway, even when playing games, an unnecessary touch error will make players feel frustrated.

From a system perspective, pressure sensor technology is naturally more direct and reliable than traditional buttons or even capacitors, resistors, ultrasonic and other technologies. It is material-independent and not easily affected by external interference, making the system more robust.

As for the chip itself, Qorvo's pressure sensor can be used continuously for 10 million to over 100 million cycles, while the life of traditional buttons is only 200,000 to 500,000 times. In addition, Qorvo has successfully shipped tens of millions of products with a zero field failure rate.

It also proves the reliability of MEMS pressure sensors. Qorvo products are waterproof, dustproof, and ice-proof, and can work in various high and low temperature environments. Its automotive-grade version has also passed AEC-Q100 certification.

Pressure Sensing and the Future of HMI

In today's fast-paced world, people are looking for products and services that make their lives and work run smoothly, save time, and ultimately improve comfort and operability. This requires a more intuitive and natural human-computer interaction experience without any interference.

In addition, considering the post-epidemic era, there will be more demand for contactless human-computer interaction, which brings differentiated demand challenges to HMI and sensors.

On the one hand, the growth of emerging technologies such as voice interaction, face recognition, and gesture recognition is transforming the human-computer interaction experience. At the same time, relatively traditional touch technology is also being continuously improved with the provision of innovative pressure sensors such as Qorvo to cope with the future.

As Will said, "Qorvo's pressure sensors can also be applied to a variety of emerging technologies, such as sleep monitoring, robotics, home appliances, etc. For Qorvo, the limit of technology depends only on the imagination of engineers."