PCT touch technology gets another harsh environment design win
Zytronic , via its Australian distributor JEA Technologies, has been able to show the effectiveness of its Projected Capacitive Technology (PCT) touch sensors in the most severe applications. A bespoke 15-inch version of the company’s ZYTOUCH product has been specified by APC Technology, a producer of industrial computing systems, for inclusion in its latest ultra-robust platform. 
The installation of electrical equipment in heavy processing facilities, such as oil refineries and chemical plants, can be very hazardous. In such demanding settings, flammable gases are likely to be present, so it is vital that every possible precaution is taken to ensure any sparks caused by electrical switching activity or fault conditions do not ignite these gases. To address this problem, APC Technology has developed an industrial PC with an enclosure which ensures that there is no possibility of an internal spark triggering an external explosion. The resultant enclosure/touchscreen design was then certified to the Exd (flameproof/explosion proof) standard.
APC Technology’s solution had to provide extreme ruggedness, while at the same time possessing a high degree of use-ability. A touchscreen interface was a logical choice, but the specification was certain to prove a challenge, as the front surface had to be very thick and completely sealed so that isolation was kept in line with IEC 60079.0/1 certifications and an IP66/67 moisture/humidity protection rating was maintained. Modelling and testing at APC Technology and Zytronic indicated that the sensor would have to be greater than any previously designed and manufactured thickened laminated and toughened glass to pass the stipulated pressure/explosion ratings. Furthermore, due to the nature of applications in which this enclosure would be deployed, the touchscreen specified also had to have the ability to be used by plant operatives wearing gloves.
Zytronic’s PCT touch sensors utilise a matrix of micro-fine capacitors embedded within a laminated substrate that can be located behind a protective overlay (usually made of glass) that safeguards against damage from external forces. This makes them highly optimised for use in difficult settings. They also support gloved operation. However, until now few applications had called for sensitivity through such thick glass.