Touchscreens defeat CTS

Article By : Bill Schweber

Predictions of a CTS epidemic due to excessive QWERTY keyboard use did not materialize due to widespread adoption of touchscreen devices.

There’s something about human nature that wants to know the future. Whether it’s via the traditional fortune teller with a crystal ball or the experts and talking heads with their veneer of credibility and special insight, we are anxious to hear their take on what the future will bring for the economy, politics, and technology. Even though most of these so-presumed seers and experts are wrong most of the time, we still stop to hear what they have to say.

One glaring example: back in the 1990s and early 2000s, we were inundated with hype and even hysteria about the coming “epidemic” of carpal tunnel syndrome (CTS). Carpal tunnel syndrome is a genuine medical condition that causes numbness, tingling, and pain in the hand and forearm. The condition occurs when one of the major nerves to the hand—the median nerve—is squeezed or compressed as it travels through the wrist (Figure 1).

Figure 1 Carpal tunnel syndrome occurs when the median nerve to the hand is squeezed or compressed as it passes through the wrist. Source: AAOS

So how did this presumed epidemic arise? The pundits and experts pointed to the fact that so many people were apparently spending all day typing on their QWERTY keyboards. This rationale ignored the fact that the people who were most likely to get it were those doing serious repetitive work such as bricklaying, construction, operating production equipment, working on meat-packing lines, and similar tasks rather than keyboarding.

The “panic” about the CTS epidemic was everywhere, with healthcare providers offering courses on how to avoid it and lawyers offering seminars on legal options if you got it—and for companies, how to protect against such injury lawsuits. Breathless warning articles were written by lazy reporters at one end and those with an interest in stirring this pot on the other end.

How did the threat of a CTS epidemic end? It certainly wasn’t due to herd immunity or a vaccine. Instead, there were two reasons. First, many of the underlying assumptions about how many hours per day people used their keyboard without a break were faulty; they were often made by editors and journalists thinking about themselves, not the broader universe of keyboard users.

But the second was more dramatic: the unforeseen adoption of touchscreens rather than fixed-layout keyboards. Perhaps the tipping point was the use of touchscreens in smartphones led by Apple and the iPhone; that overtook and obsoleted the tiny QWERTY keyboards of the Blackberry, which was once the “must-have” wireless device, as recounted in “Losing the Signal: The Untold Story Behind the Extraordinary Rise and Spectacular Fall of BlackBerry” and “Build.”

While the traditional “ancient” QWERTY keyboard is still widely used, it no longer totally dominates as the human-machine interface (HMI). Kiosks, point of sale (POS) terminals, smartphones, tablets, and many other products now use touchscreens (Figure 2). In short: technology took care of that “epidemic” in a way that was not anticipated.

Figure 2 Touchscreens in everything from kiosks to tablets have dramatically reduced the amount of non-stop keyboarding use. Sources: Team Conasauga

In fact, touchscreen technology has come a long way, and there’s no doubt that touch-driven display interfaces are certainly the preferred or only viable option in many cases. They offer flexibility, dynamic reconfigurability, user convenience and safety, and many other virtues compared to a standard keyboard or even dedicated, hardwired switches and knobs.

Still, there are also many applications where the user of a touch-based interface also needs an old-fashioned analog-like rotary knob to provide intuitive, natural input action for a key parameter such as temperature or audio volume. Addressing this mixed input-mode requirement, Microchip Technology Inc. has introduced the maXTouch Knob-on-Display (KoD) family of touchscreen controller ICs for screens up to 19 inches, which they maintain is the first automotive-grade touchscreen controller family with native support for the detection of and reporting on capacitive-based rotary encoders.

Among its other features, the controller ICs with SPI and I2C interfaces reduce the number of active components needed to create a modern HMI design (Figure 3). You get both the appearance and flexibility of a touch display combined with the convenience, comfort, and directness of an old-fashioned, natural-feel control knob.

Figure 3 The knob-on-display technology adds a classic rotary knob to modern touch displays. Source: Microchip

From an engineering perspective, what’s especially interesting is that this touch-related technology supports mounting the knob directly onto the display without an opening in the panel or any customization of the touch pattern (Figure 4). This increases design flexibility and potential reliability, leading to system-level cost savings. It’s not just for automotive applications, either, as it also enables design of a sealed HMI module, which is increasingly popular for in-home appliance and industrial applications.

Figure 4 This cutaway sideview makes clear that the rotary knob does not require an opening in the front panel or display, which enhances physical integrity of the final design and reduces manufacturing cost. Source: Microchip

The knob itself is a passive mechanical element and is specifically designed to include at least one conductive pad (Figure 5). The maXTouch KoD touchscreen controller senses the pad capacitively through the touch sensor. Its patented algorithms ensure the correct sensing and calibration of the knob’s location while maintaining multi-touch operation over the rest of the touchscreen. As it does not require a specific touch-sensor pattern under the knobs, it can be used with a standard touch display.

Figure 5 The rotary knob is sensed via capacitive coupling, a reliable and well-established non-contact technique. Source: Microchip

We’re now seeing stories on the next epidemic of spine, back, and shoulder problems due to people hunching all day over their smartphones. But unforeseen disruption is the rule more than the exception. To stay “grounded,” keep in mind the simple but insightful statement by the late baseball great and no-nonsense philosopher Yogi Berra, who supposedly quipped, “‘It’s tough to make predictions, especially about the future.” It seems to me that sums it up well.

Are there predictions that went very far wrong, which stick out in your mind?


This article was originally published on Planet Analog.

Bill Schweber is an electronics engineer who has written three textbooks on electronic communications systems, as well as hundreds of technical articles, opinion columns, and product features. In past roles, he worked as a technical website manager for multiple EE Times sites and as both Executive Editor and Analog Editor at EDN. At Analog Devices, he was in marketing communications; as a result, he has been on both sides of the technical PR function, presenting company products, stories, and messages to the media and also as the recipient of these. Prior to the marcom role at Analog, Bill was Associate Editor of its respected technical journal, and also worked in its product marketing and applications engineering groups. Before those roles, he was at Instron Corp., doing hands-on analog- and power-circuit design and systems integration for materials-testing machine controls. He has a BSEE from Columbia University and an MSEE from the University of Massachusetts, is a Registered Professional Engineer, and holds an Advanced Class amateur radio license. He has also planned, written, and presented online courses on a variety of engineering topics, including MOSFET basics, ADC selection, and driving LEDs.


Leave a comment