Sunlight readable displays for explosion-protected HMI systems

The displays of conventional HMI
systems show a distinct glare
in strong sunlight (top), while
innovative displays ensure
much better readability(middle)

The PC-based, explosion-protected operating systems from Stahl's Open HMI series can now, on request, be fitted with innovative 15" displays that reduce glare and reflections to a minimum. The displays of these models can be read easily even in bright sunlight, since a filter pack effectively diverts even strong incoming ambient light. The new solution is based on a very effective combination of polarisation filters placed on top of and behind one another in front of the display.

Many important operating and monitoring tasks are carried out at HMI systems installed outdoors. This can only be done safely and easily if the displays do not reflect ambient light too strongly. Thanks to the new solution, bulky canopies that were supposed to give shade but in practice hardly did so to a sufficient degree are no longer necessary.

High Brightness displays, which caused thermal problems in explosion-protected systems in particular and which were similarly useless against glare, are also no longer necessary, as the new package does not require particularly bright LEDs. Unlike any standard filters used so far, this filter pack hardly affects the image display for viewers: although the sunlight readable displays can be adjusted to up to 1,000 cd/m², they are already easily readable even in direct sunlight with a luminescence of 700 to 800 cd/m².

Certified for hazardous gas and dust explosion zones 1, 21, 2 and 22, the Open HMIs are fitted with low-energy CPUs from the Intel Atom series and consist of explosion-protected modules. These touchscreen systems can be operated in rugged environments and even at continuously extreme ambient temperatures between -30 °C and +50 °C. Numerous international certifications ensure suitability for various applications in a wide range of industries, such as the oil and gas sector, package units and the chemical and pharmaceutical industries.