Human Machine Interfaces (HMI’s) are increasingly replacing mechanical dials, buttons and levers with touch screen technology. The proprietary Projected Capacitive Technology (PCT™) developed by Zytronic has on many occasions proved its ability to be employed in the most uncompromising of environments – including the extreme conditions encountered in the oil industry, and mining applications. Its touch screens are designed to operate in the most extreme environments offering a robust, waterproof, and hygienic solution that will detect a finger, conductive stylus and even a gloved hand, through glass thickness of 20mm or more. Recent successes in heavy industry have further underlined this, showing its superior performance over alternative touch solutions.

Touch in an explosive environment

Suitably designed touch screens can be efficiently used in hazardous and explosive (Zone 1) applications such as oil rigs. Smart-Ex terminals  enable the collection and analysis of data by operatives on drilling rigs, and depend upon a rugged human machine interface (HMI) that is easy to use – so that vital information can be rapidly viewed, understood and then acted upon. This is combined with a high degree of isolation – so that the electrical hardware inside the terminals does not come into contact with the potentially combustible gases and liquids outside. It is essential that the chosen touch technology is capable of faultless outdoor 24/7 operation, exposure to corrosive salt water, and oil, while remaining responsive to the touches of users wearing heavy work gloves.

Touch screen solutions based on conventional projective capacitance (p-cap) methods would be incapable of coping with such a demanding set of criteria, as they lack the sensitivity to determine touch events through more than one or two mm of front glass. However, Zytronic’s technology is particularly suited to, and proven in, applications of this kind due to their unique construction and sensing method.

The near invisible XY matrix of highly conductive capacitors that make up PCT sensors, are a mere 10 microns in diameter. Zytronic’s proprietary self-capacitive touch sensing technique induces a known frequency (around 1 MHz) within these capacitors, which in turn, is altered by a user’s body capacitance when their finger comes in proximity with that part of the touch screen’s surface. Through sophisticated algorithms embedded within the connected touch controller’s firmware, the position of peak frequency change is interpolated. This method of touch detection is so sensitive, that the PCT sensor matrix may be embedded within a laminated, thick protective overlay. The firmware may also be easily tuned by the user via a driver to adjust touch sensitivity and threshold detection levels so that the screen will respond to the lightest of touches or full finger pressure, depending on application requirements. It can also support heavily gloved hand operation, making it highly optimised for outdoor and industrial applications. Zytronic’s proprietary ZXY110 touch controller can also implement a ‘smart’ frequency-scanning function to combat EMI interference. The operating frequency moves dynamically between 1.3MHz and 2.5MHz in order to avoid detected environmental ‘noise’ that would otherwise prevent the detection of touch events.

Customised 15 and 19-inch versions of the highly rugged PCT touch sensors have been integrated into the Smart-EX terminals, along with ZXY100 high performance touch controllers, and they are already being deployed on oil rigs around the globe. Using thermally toughened glass with thicknesses of up to 23 mm, these touch interactive terminals are capable of coping with the rigours of Zone 1 hazardous environments.

“Maintaining touch performance through such thick protective overlays would be way beyond the scope of competing p-cap solutions,” Ian Crosby, Sales & Marketing Director at Zytronic explains. “This meant the PCT stood out as the only way to bring the benefits of touch enabled interaction to this challenging application. Our collaboration with Smart-EX represents another important example of how Zytronic’s unique touch technology, is aiding designers of human-machine interfaces to deploy touch screens in the most challenging surroundings.”

Australian mine application

Leading Australian kiosk manufacturer FM Scanu is another company that endorsed Zytronic’s highly durable Project Capacitive Technology (PCT™), selecting the exceptional touch screen technology for use within units deployed at mining giant BHP Billiton. The resulting ruggedized kiosks were designed to aid the management of mine personnel, and make use of the market leading performance of the touch technology by integrating a 17″ ZYPOS® touch sensor. The units are used to supply occupational health and safety information in the midst of a hectic excavation environment and Zytronic’s PCT™ screens ensure that the touch screens are virtually immune to damage.

The ZYPOS® sensor consistently delivered a reliable high-standard performance, which was crucial in such a demanding environment, where coal dust, grit and moisture are prevalent. Zytronic were more than able to provide a touch screen technology solution that could stand up to the harshest environments and still perform well. The kiosk’s operation was also unaffected when used with a gloved or dirty hand, so that information could be accessed without the hindrance.

Zytronic’s hugely successful PCT™ touch sensing method of embedding microfine copper wire in a durable laminated substrate, means that its use is quick and effortless. Even if, as in this case, the tough, all glass PCT™ sensor is mounted behind (and functions through) an additional thick protective overlay of glass.

As another huge benefit, especially useful to a mining environment is the fact that PCT™ is not prone to drift over time, and can be completely sealed into IP67 enclosures. Making it ideal for demanding industrial, outdoor and/or public-use touch interactivity where high levels of reliability and “up-time” are a pre-requisite.

Conclusion

These two applications demonstrate that there is almost no environment that is too difficult for touch technology. Zytronic PCT sensors can be protected and sealed into a suitably rugged enclosure and operate reliably from behind glass responding to operators who are themselves wearing protective workwear such as gloves.