Warmth from sunlight, as well as causing glare, can also heat up the sensor in a touchscreen and cause issues. An infra-red film can be fitted to the rear of the sensor to reduce the transmission of IR energy, providing designers with a useful tool for cooling.
In extremely hot environments, cooling can also be provided with an active cooling system – which is an additional “force fed” fan system which pulls in colder air and forces out warm air, creating circulation of air directly over hot components to cool them. However, a problem with this method is when the ambient temperature is too hot, the air being pulled into the system is not sufficiently cold enough to provide any cooling effect. In extremely hot environments, thermo-electric conditioning units would be more effective. These air conditioning units pull warm air over compressed gas to produce a cooling effect.
Zytronic touchscreens can be manufactured to function perfectly up to 70°C – ensuring performance in some of the world’s hottest climates. Humidity is also a non-issue, as long as the system is fully sealed, and the unit does not permit moisture ingress. Displays must be carefully selected by manufacturers to ensure they function in this level of heat.
Temperature tolerance is important in cold environments for a number of reasons. Freezing temperatures can damage glass touch panels – so any glass specified for use in cold must be incredibly robust. Zytronic’s glass can withstand temperatures down to -35°C.
Cold also means users are likely to wear gloves. On some touchscreens that rely solely on electricity, gloves create a barrier between skin and screen and therefore prevent a user’s touch being detected. Any touchscreen produced for use in the cold must therefore function even when a user is wearing gloves.
Snow and ice, like rain, carry the same moisture issues. However, due to the heat of the display below the touch panel, neither are likely to impact performance as they will melt to water – which is ignored by Zytronic’s unique technology.
One of the main considerations of touchscreens placed outdoors is their vulnerability to damage and vandalism. Whether your product is exposed to accidental scrapes as part of its service life, or it is exposed to intentional damage, tampering or theft, a touchscreen used outdoors should be able to mitigate risks as efficiently as possible.
To protect against damage, the glass that houses a touch panel must be tough enough to withstand direct impact and to not compromise performance. Achieving this is made possible by thermally or chemically strengthening the glass fronted touch sensor. Chemically toughening glass is a process whereby glass is submerged into a heated, potassium salt bath. This causes the sodium ions in the glass to be replaced with larger potassium ions, creating compression on the surface of the glass as well as traction stresses in the core. This process creates glass that is up to 8 times stronger than float glass. However, when broken, the glass will shatter into large splinters which could cause severe injury to any nearby users. To ensure health and safety, outdoor units may therefore need to choose a different option.
Thermal toughening is perhaps a more suitable alternative for outdoor applications where health and safety is a concern. The process involves raising the temperature of glass to near melting point, and then rapidly cooling it. This creates tension within the glass and compression on its exterior. When it breaks, it will instead break into small granular pieces rather than dangerous shards.
Impacts and scratching are both issues faced by outdoor touchscreens – and are again issues that can be mitigated by selecting the right glass. Thick, toughened glass touch panels such as ZyBrid multi-touch sensor can withstand impacts and abrasions that would cause damage in thinner glass, so manufacturers must ensure they select the appropriate thickness. In addition, touchscreens can be sealed in different styles at their edges to further protect against breakage.
Many outdoor units are left in unprotected areas, and as such as sadly subject to vandalism. Whether this is a direct attempt to break a screen, graffiti or theft, a touchscreen must be able to offer protection. At a minimum, strengthened glass helps prevent possible legal issues that may arise if a vandal injures themselves on shards.
Zytronic’s touchscreen technology can still function even if the glass breaks under a particularly determined damage attempt, which means users can still interact with a unit until a fix is available.
In banking and other data-sensitive applications, touchscreens may also need to be encrypted to provide total user security. This means selecting a touchscreen with chip-set and firmware that adheres to Payment Card Industry (PCI) compliant systems.
Advice for installers
When specifying a touchscreen for a product that will be used outdoors, it is important to consider and mitigate the above issues. You should contact a manufacturer early on in your design process, who can then work with you to design the right touch panel for your needs.
To avoid rain or moisture ingress, touchscreens should be fully sealed within glass and given an IP rating to ensure reliable performance in all weathers. The controller itself must be able to ignore rain on a screen to ensure good performance even when wet. You must also ensure that if you are using a front metal bezel to seal the unit, a plastic frame must be installed to create insulation between the screen and controller that is unaffected by water.
To provide functional performance when under direct light, a touchscreen can be specified with anti-glare measures, and fitted to a display such as a TFT-LCD that offers high brightness settings. In fact, the actual LCD chosen is very important – as only bright, full colour screens will attract the right attention in the outdoor space. This is another factor a touchscreen manufacturer can assist with, allowing you to work together to choose the right touch panel for your specific LCD’s specification.
Dirt and dust will be a factor outdoors, so any technology specified must function when either is present on the screen.
Temperature requires implementing a touch panel and a display that can withstand the temperature range of your target location. For example, if creating a range of units for use in a middle-eastern country, heat is more of a focus and may necessitate installing air cooling systems with in your products. Zytronic’s projective capacitance technology automatically adjusts capacitance to ensure performance during temperature changes.
Manufacturers will likely already be aware of the risk of damage and vandalism in any outdoor product – but must consider that the visibility and ‘first point of contact’ nature of touch panels makes them a prime target for vandalism.
As such, manufacturers must design a product whereby the touchscreen is seamlessly integrated and utilises thick, toughened glass that does not shatter. This makes it less likely to be tampered with, and harder to vandalise. Zytronic offers responsive touch experiences that function perfectly even with glass that is up to 10mm thick, making it resistant to almost any form of impact.
Despite this, a determined vandal may still be able to break a touch panel, especially in an unattended outdoor space where they have the time to do so, but by preventing shatter you are protecting your system and also avoiding any legal ramifications.