PCT™ touch sensors integrated into explosion-proof HMI solution targeted at use in hazardous areas
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. Recent successes in heavy industry have further underlined this, showing its superior performance over alternative touch solutions. Among these successes are the inclusion of the company’s ZYTOUCH® and ZYBRID® products by ‘mission critical’ process controls manufacturer iSiS-Ex in their new range of explosion-proof terminals designed for use in offshore oil and gas drilling.
Enabling the collection and analysis of data by operatives on drilling rigs, these terminals 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; 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 - thereby putting lives at risk. In addition, due to the incredibly tough working environment in which the terminals are deployed, it is essential that the chosen touch technology is capable of faultless outdoor 24/7 operation, exposure to corrosive salt water and oil, plus response to the touches of users wearing heavy work gloves.
Touchscreen 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 PCT™ touch sensor products are particularly suited to, and are 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 touchscreen’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.
Customised 15 and 19-inch versions of the highly rugged PCT™ touch sensors have been integrated into the iSiS-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 iSiS-Ex represents another important example of how Zytronic’s unique touch technology, is aiding designers of human-machine interfaces deploy touchscreens in the most challenging surroundings.”