Touchscreen Display Design
for Industrial Applications
Industry 4.0 is here, and the demand for “smart” equipment and HMI is booming. Engineers, designers, and operations teams across the globe have been tasked with reimagining everything from factory floors, equipment controls, fluid dispensing equipment, handheld devices, and more. While modernizing production for increased safety, efficiency, and reliability can be a game changer, this is no small task.
The days of resistive film-front touchscreens and flimsy button pads that wear out prematurely are fading fast. Projected Capacitive (PCAP) touchscreens have made it from our smartphones and tablets to the factory floor. Multi-touch, gesture, and bezel-free designs have grown from top-shelf luxury to standard expectations. If refrigerators can have giant bezel-free touchscreens, why shouldn’t an expensive piece of industrial equipment?
Heavy-duty applications and harsh environments pose unique challenges for sensitive electronics and fragile materials like glass or plastic that you would typically find in a capacitive touchscreen device. Operators are commonly required to go from tough, hands-on labor to careful interface controls, sometimes hundreds of times a day. Devices may get cleaned with the harshest of chemicals or never cleaned at all. So how can we design touch displays to help companies deploy this new wave of Industry? Let’s cover the big 3.
1 – Heavy Duty Cover Glass and Coatings
Arguably the most critical element of industrial touch displays is the cover glass – it’s the surface that gets touched, handled, bumped into, and constantly exposed to the environment. Most commercial touch displays will use a .5-2mm cover glass made from either glass or a combination of plastic plates and films. While these materials might work great for applications like tablets, self-service kiosks, or the controls for that snazzy new wifi-enabled Ai-IoT-smart-toaster-slash-pizza oven, you just had to have, they wouldn’t survive for long in something like an oil refinery or a steel fabrication shop.
Plastic cover layers are perfect for things like aerospace, automotive, and wearable devices because plastic can be thin, lightweight, and for the most part, doesn’t get beat on. However, plastic is largely out of this discussion because heat, chemicals, scratching, and impacts are just some of the environmental challenges industrial applications have to deal with. Gloves, for example, are designed to keep operator hands clean and protected, which means they get dirty. They pick up fluids, grease, dirt, metal shavings, and other harsh materials, which then get mashed on the controls during operation. Operators may have tools or materials in their hand while operating or near the touch display, and occasional impacts are inevitable. Plastic has come a long way in terms of hardness levels and can be enhanced to increase durability, but it’s not ideal for the challenges of most industrial environments.
To tackle these challenges, we use a range of technical glass that has been manufactured and enhanced to exceed common commercial or architectural glass standards. Starting with a 9H+ hardness that plastic cannot achieve, we can take it a step further by enhancements such as acid-etching, chemical-strengthening, tempering, and specialized coatings. Etching and coatings can achieve better functional performance and user experience by adding anti-fingerprint, anti-reflection, anti-smudge, anti-bacterial, and other features that can drastically improve the performance of touch displays.
Specifying cover glass composition and enhancements also requires balancing the thickness of the cover layer itself. Thickness can range from 2mm up to 10mm or greater, depending on what it needs to survive and the type of glass or enhancements specified. Thickness and glass composition needs are generally determined by the kind of impact or breakage risk to the device. There are a variety of standard tests to help determine the level of ruggedization required, like ball-drop, boot-kick, head-impact, and so forth.
Our goal in any high-reliability application is to engineer products that can meet or exceed industrial lifecycles with the perfect balance of durability and functionality, while avoiding adding excessive weight, cost, or compromising the optical performance of the display.
2 – Custom Firmware & Tuning
Many industrial environments, equipment categories, and types of labor require operators to wear gloves. These can range from thin nitrile gloves to heavy-duty, fire-grade gloves made of thick leather. Since PCAP touchscreens require your finger (or grounded conductive material) to detect touch, this can be a problem. TI standard PCAP sensors work with thin nitrile or rubber (surgical type) gloves out of the box with no tuning required. Some gloves are now made with unique materials in the fingers to pass-through conductivity so technicians can operate tablets and smartphones; thus, no special tuning is required. Unfortunately, most heavy-duty gloves are not, and since they are a consumable cost where durability is paramount, it’s unlikely they ever will be. Leather is tough to beat. Unfortunately, leather also blocks conductivity. In some instances, like working around high-voltage equipment where all leather is mandatory.
Touch controller firmware must be tuned to sense touch through the type of glove or range of glove types operators will be using. TI Standard PCAP sensors and all of TI’s OFX open frame monitors can be tuned to handle virtually any glove, including picture and slash-resistant gloves commonly used by firefighters.
One challenge for PCAP is outdoor or rugged environments exposed to rain or moisture. Rain, salt water (highly conductive), mist, and industrial fluids can cause a myriad of touchscreen performance problems, and the results can be dangerous. If the wrong button gets clicked on your phone, you might get embarrassed. If the wrong button gets pushed on an oil rig, you’ve got bigger problems. When tuning for gloves or anything else, it is crucial to take into consideration the types of environments the touch display will be deployed in and tune accordingly to filter out things like noise and false touches, and at the same time not emit more EMI noise that can affect other equipment and cause regulatory or certification problems.
3 – Extended Temperature Operation
Environmental concerns are not exclusive to industrial touchscreens. However, industrial applications can see a far greater range of ambient temperatures or direct sunlight than your typical commercial touch devices. While it’s essential that the materials specified to manufacture the touchscreen can survive blazing heat, freezing cold, or Mike Tyson pumping gas, the LCD display behind that stack-up is where the money is at. Without diving into the chemistry of LCDs, displays commonly found in commercial devices have operating temperature ranges of 0 to 50C degrees (32F to 122F). If the LCD gets too hot, it washes out, and you can’t see the screen. If it gets too cold, you can’t see the screen until it warms up to operating range, and in some extreme cases, the crystal fluid inside the LCD can freeze, causing permanent damage.
For industrial, military, and other heavy-duty applications to be deployed around the globe, from deserts to the arctic, you have to start with an extended temperature LCD. These typically operate within the degree range of -35 to 85C (-32 to 185F). No warm-ups, no wash-out, and no additional heaters or heat-shielding required. For extreme applications, you can always add further enhancements such as LCD heaters and a variety of heat and solar-shielding options to ensure high reliability regardless of where the device is deployed.
As with most devices, regardless of market or application, your final product is only as good as your user experience. If operators have a hard time using the equipment, at best, you’ll have a hard time selling it. If it wears out prematurely or gets punched, you can be stuck covering warranty claims and losing customers. If it looks great, meets performance expectations, and operators love using it, you’ve got a customer for life.
The majority of TI’s OFX open frame monitors start with an extended temperature LCD, making them a great baseline to customize for any industrial application. Regarding cover glass, TI has developed proprietary glass formulas that combine the scratch-resistant properties of high-priced borosilicate glass with the break and shatter resistance found in common soda-lime glass. It comes standard with an anti-glare, anti-fingerprint coating. We call it Nippon glass, which comes standard on our OFX monitors because it’s very cost-effective and easy to customize. It’s perfect for industrial applications, and we’d love to discuss it with you. Call us maybe?
Until next time, Keep in Touch!
Director of Marketing, Touch International