What Makes Capacitive Touch So Versatile
The continuing advancement in capacitive touch technology has made it possible for modern capacitive touch screens to become the leading, or primary, user interface of choice. Early capacitive touch screens were limited in capability, whereas today’s touch screens can detect multiple fingers, reject water, know when gloves are worn, and work through thick protective glass or acrylic.
With 25 years in the industry, Amulet has had a front-row seat to the many advancements in capacitive touch technology and has taken a keen interest in how best to utilize this tech in our products. Here is a little about the background and the most noteworthy changes in features that will help inform your decision in choosing the correct touch display for your next project.
Early History
Capacitive displays were limited in capability due to hardware and software constraints when first released commercially in the early 90’s. The early capacitive screens typically used less capable electronics and less sophisticated sensors, which limited their sensitivity and resolution. The electrodes that formed the capacitive grid on these early screens were often larger and spaced widely, which reduced the precision with which touches could be detected. This configuration made it difficult to accurately register delicate or light touches. It effectively prevented the implementation of features like multi-touch, which require the detection of multiple points of contact with high accuracy.
Moreover, the signal processing algorithms utilized in early capacitive touch controllers were not as advanced as they are today. These initial algorithms faced significant challenges in differentiating between intentional touches and environmental noise or unintended touches, such as those caused by water droplets or accidental palm touches. However, with the advancements in technology, these algorithms have significantly improved, allowing for more accurate touch detection and interpretation.
Advancements in manufacturing techniques were not the only factors that propelled the evolution of touchscreen technology. The strides made in microprocessor design and digital signal processing algorithms were equally significant. These developments, combined with the creation of smaller and more densely packed electrode grids, enhanced the touchscreens’ ability to detect and interpret a broader range of touch interactions with greater accuracy. These advancements result in the sophisticated, highly responsive capacitive touchscreens we use today, supporting complex gestures and touch filtering across various devices.
Capacitive Technology Enhanced Features
Recent enhancements in capacitive touchscreen technology have revolutionized how users interact with devices in various environments. These advancements include multi-touch capabilities, water rejection features, improved glove detection, and the integration of protective cover glass, each contributing significantly to the functionality and usability of touch-driven interfaces.
Multi-Touch Capability
The introduction of multi-touch capability, which allows a touchscreen to recognize and respond to more than one point of contact simultaneously, was a significant leap forward in capacitive touch technology. The real breakthrough came with the introduction of advanced capacitive sensors and sophisticated signal-processing algorithms. These sensors featured finer, more densely packed electrode grids that could capture more detailed changes in the electrostatic field caused by multiple fingers. The algorithms could interpret complex electrical activity patterns, distinguishing between tracking numerous touches. This technology was crucial for developing intuitive gesture-based interfaces, such as pinching or spreading fingers to zoom in or out, which have since become standard in touch-driven devices. When Raypak Inc., an industrial water boiler company, investigated modernizing and digitizing their boiler controls, they looked toward incorporating a capacitive touch display. One of the innovative features was offering a document viewer to look up user manuals and schematics, which utilized the pinch-zoom and pan functions.
Water Rejection
Water rejection and detection capabilities in capacitive touchscreens are crucial developments that significantly improve the usability of devices in various environments. A typical human touch generates a distinct, predictable change in the screen’s electrostatic field, characterized by a specific size, shape, and dynamic interaction pattern. In contrast, water droplets might create irregular or shifting disturbances, which the system can effectively ignore or filter these inputs. This prevents false touches, ensuring the device only responds to genuine human interaction. This capability ensures reliability, especially in outdoor environments or operating rooms where moisture is common. An excellent example of such a device with this capability is the digital Kohler shower head controller, which controls water pressure and temperature, adjusts the lights, and even controls the music, all from within the highly wet shower conditions.
Glove Detection
The enhancement of glove detection in capacitive touchscreen technology represents a significant advancement, broadening the applicability of touchscreens in various professional settings, including healthcare. Advanced algorithms enhance and decode the weaker signals through non-conductive materials like latex or nitrile gloves. They adjust sensitivity and compensate for lower capacitance, ensuring touches are accurately and reliably registered. As a result, doctors and healthcare professionals can interact with medical devices and touch-enabled control systems without removing their gloves, enhancing both usability and compliance with hygiene protocols. This capability has increased the adoption of capacitive touchscreens in medical technology and improved operational efficiency and user experience, making capacitive touchscreens a more versatile and indispensable tool in clinical settings such as Stryker Endoscopy’s endoscope platform. The endoscope is a small medical camera that looks into the human body without surgery. The doctor controls the camera through various touchscreens on the machine during the procedure and requires sterile gloves. This feature enables the screens to detect the touch of a finger even through medical gloves, which is crucial for maintaining hygiene and safety in the use of medical devices.
Protection
Capacitive touch screens are now engineered to function effectively even when covered by thick protective materials such as Gorilla Glass, which is known for its durability and resistance to damage. The secret lies in the capacitive sensors’ enhanced sensitivity and precision. These sensors can detect the slight electrical disturbances caused by a finger, even through layers of dense, protective glass. This is made possible by boosting the electric field strength generated by the touch screen’s electrodes, which extends the field’s reach through the thicker glass without compromising the accuracy of the touch detection. Additionally, the electronics behind the screen are tuned to discern and react to the subtle changes in capacitance that occur when a finger approaches the glass surface, thus ensuring that the touch interface remains responsive and reliable, no matter the protective barrier. This capability not only protects the screen from physical damage but also maintains a high-quality user experience. Modern smartphones and tablets often feature Gorilla Glass or other types of protective, durable glass. This advanced glass technology is designed to withstand everyday bumps and drops, significantly reducing the risk of scratches and breakages, thereby preserving the aesthetic and functional integrity of these devices.
Conclusion
The remarkable advancements in capacitive touchscreen technology—specifically multi-touch capability, water rejection, glove detection, and the ability to operate through thick protective glass or acrylic—have been pivotal in cementing its dominance as the interface of choice across consumer and industrial applications.
The introduction of multi-touch has revolutionized user interaction, providing intuitive and dynamic control that enhances the user experience. Water rejection ensures reliability and accuracy in moist environments, preventing false touches that could disrupt user interaction. Glove detection has opened new avenues in sectors such as healthcare, where maintaining sterile conditions is essential, allowing professionals to operate touch-based devices without compromising on safety or convenience. Finally, the ability to detect touches through protective barriers has not only increased the durability of devices but also broadened their usability in harsh or public environments. Together, these enhancements have significantly expanded the functionality and adaptability of capacitive touchscreens, making them the undisputed leader in touch technology across a spectrum of everyday and specialized devices.
We hope this little venture into the advancements of capacitive screen technology has opened your eyes to the many capabilities of the capacitive screen. We have partnered with many developers to include smart displays in their projects, ensuring they stay at the forefront of GUI technology and provide an optimal user experience. Amulet Technologies has implemented all these enhanced features in various customer products, exceeding expectations and satisfaction. From Kohler’s shower control to Stryker’s Endoscope, Amulet’s capacitive smart displays can be found where innovative displays are used. Check out this YouTube video if you want to see a quick demonstration of all these enhancements. We would love to chat with you about your products and how your application can benefit from a capacitive touch interface. Please contact Amulet Technologies at info@amulettechnologies.com
Johnny Gohata, Amulet’s marketing director and overall information guru. With more than 35 years in the high-tech arena that is Silicon Valley, he started his career as an ASIC FAE, branching into sales and marketing for various start-ups, which ultimately landed him at Amulet Technologies. With a pioneering role in developing applications for smart displays, Johnny has mastered the art of converting complex problems into elegant and simple solutions. In his free time, he likes to drive his Tesla, learn about artificial intelligence, and dabble in Python programming.