Touchscreens are one of the most common methods of interacting with devices ranging from cellphones and wearables to smart appliances and automotive systems. While the concept of touchscreens has existed since the 1960s, it was only in the past couple of decades that compact and affordable touch sensor panels (such as capacitive and resistive ones) have entered the market, revolutionizing consumer electronics and becoming a staple of modern life.
Touch controllers are a vital component of modern display technology.
Still, many people believe touch panels lack the tactile feel and feedback of traditional buttons, knobs, and switches. Some manufacturers are working on new ways to improve the user experience of consumer electronics by creating technologies that mimic the feeling of these components and even infuse touch sensors with mechanical elements.
This article focuses on the control side of this equation, diving into the details of three ICs announced in recent months by prominent semiconductor manufacturers. These devices were designed to enhance the input methods of next-generation electronic devices.
Microchip Supports Rotary Encoders on Top of Touchscreens
In June, Microchip Technology announced a new type of touch display chip that makes it easier for engineers to integrate the interactive input capabilities of multi-touch displays with the tactile feel of mechanical rotary encoders.
maXTouch Knob-on-Display (KoD) is a family of touch controller ICs that natively support capacitive rotary encoders and mechanical switches mounted onto existing touch displays without needing custom panel shapes and cutouts.
Traditional HMI architecture compared to Microchip’s single-chip touch IC system. Image courtesy of Microchip
According to the company, the Knob-on-Display chips would allow designers to incorporate multiple turnkey knobs of different styles into a single traditional touch display for use in various types of products ranging from in-vehicle systems to smart household appliances.
Microchip aims to simplify the development process of these devices through a comprehensive suite of both hardware and software tools while also improving the user experience and increasing automotive safety. With the new touch controller technology, users can manage volume and temperature without looking away from the road and at a display.
The maXTouch KoD family includes two variants (KD and MK) of two different LQFP packaged chips: the 112 touch channel ATMXT2912TD-A and the 97 touch channel ATMXT2113TD-A. The KD chip variants allow manufacturers to create their own knob design based on a reference provided by Microchip in partnership with BNL Bearings, while the MK chip variants support Panasonic’s capacitive rotary Magic Knob element.
ST Develops Touch Controller for Flexible AMOLED Displays
Another recent development in touch technology comes from STMicroelectronics with a new touch controller IC. The FingerTip FTG2-SLP is designed to operate with the latest energy-saving and efficiency-oriented AMOLED displays, which can dynamically control their refresh rates depending on the types of apps they’re showing.
Created primarily for the smartphone industry, the FingerTip FTG2-SLP is a 32-bit Arm Cortex-M4 core-based capacitive multitouch screen controller capable of running in synchronous and asynchronous modes. The device is also said to maintain a seamless interaction between the user and the device with a display refresh rate that changes dynamically.
The FTG2-SLP. Image courtesy of STMicroelectronics
ST’s touch controller comprises advanced features such as enhanced noise suppression and filtering and a fast report rate of 240 Hz. The FTG2-SLP also supports thin, flat, curved, and even flexible LTPO (low-temperature polycrystalline oxide) AMOLED panels thanks to its differential and node compensation hardware and differential data processing software.
The chip also features a special hibernation mode designed to further increase battery life on top of its low-power displays. ST has already launched production of the FTG2-SLP to find a home in the next generation of flexible and foldable smartphones.
CTT Makes Control SoC for Piezoelectric Touch Panel
Earlier this year, Cambridge Touch Technologies (CTT), a company established in 2011 as a spinoff from the University of Cambridge, announced the development of a new force touch controller system-on-chip (SoC) to improve the user experience in smart devices.
Named UTA3221, this chip was designed to work in conjunction with CTT’s proprietary UltraTouch sensor platform that combines a thin and flexible piezoelectric film with advanced AI and machine learning algorithms to provide a more pleasant and tactile interaction method.
Diagram of how CTT’s UltraTouch technology works. Image courtesy of Cambridge Touch Technologies
According to the company, its force touch technology can deliver the feel of mechanical buttons while also operating in the rain, underwater, and even while the user is wearing gloves, which is difficult to achieve with other touch input methods like capacitive touchscreens.
The UTA3221 IC itself is a low-powered Arm Cortex-M CPU-based touch controller that comes in a 76-pin QFN package. CTT claims this chip can process up to ten different force touch points at once. It also includes a standout sensitivity and noise floor, making it useful for the types of signals generated by piezoelectric devices.
CTT offers samples and evaluation kits to manufacturers and designers interested in incorporating UltraTouch and the UTA3221 into their own technology targeting the automotive, industrial, and medical fields.
Advancing Touch Input for Consumer Electronics
As embedded microprocessors become more powerful and more versatile, combining them with the latest sensor and display technologies is a surefire way to enhance the level of interaction between humans and machines.
Sitting at the forefront of this field are companies like Microchip, ST, and CTT that offer engineers more options to develop and design systems and products, ranging from advanced and alternative tactile touch components to ultra-high refresh and response rate sensors. Touch is likely to remain the primary input method in the smartphone, automotive, and appliance industries, and new advances at the chip level may be key to enhancing the safety and user experience of these consumer electronics.
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