There is a great deal to consider when thinking of how the sun alone will impact outdoor displays. The LCD is not the only critical component that is affected by the harsh environments. Most electrical components are rated up to certain temperatures and cannot be exposed to moisture or particulate debris. Consider the following when it comes to the impact of temperature and humidity on outdoor/semi-outdoor digital displays.
Transit displays must:
• Be designed for ambient temperatures down to - 30°F and up to 122°F.
• Be designed and validated for high temperatures and direct sun load.
• Have a display that is “sealed” to prevent condensation forming inside the cover glass.
• Have a start-up procedure for low temp power up if temperature is below - 30 F.
• Be designed for excessive shock and vibration (passing trains / buses)
• Plan for when the display is not to be run. Consider just turning off the backlight, not the entire digital display
• Have embedded electronics (player, modem, etc.) that are rated for internal display temperatures.
• Cooling is critical. Conventional A/C systems will drip, require maintenance and consume significant power. Pick a display that has the fewest failure mechanisms. If the cooling system fails, the display will too. Consider alternative cooling methods.
• Be prepared for how temperature fluctuations can affect brightness.
• Digital display AND mounting structure must be able to withstand significant wind loads. Have you thought about Gail winds, -hurricane force?
While the considerations related to sun, temperature, and humidity may seem overwhelming, once they are factored into your outdoor display purchase and deployment, you can rest easier knowing you have taken every precaution to protect your investment. Beyond environmental conditions, also mull over installation, operational and service conditions.
Other Considerations for Transit Displays
If you are thinking of placing your digital displays on or near public property, you would be wise to do the research about the area. Cities may require permits. There could be restrictions relative to full-motion video content or static transitions, especially near streets. What are the rules about nighttime operation? Many structures on public properties must be certified by a professional engineer and union or safety personnel may be required for the installation. Beyond government regulations, it is important to consider some of the more practical issues that are often times overlooked. Communication to your display through a wireless modem must be reliable. How is the cellular service in the area? Cellular service has proven to be more reliable than WI-FI. How will power be run to the display, and who is responsible for paying for it? Remember, outdoor displays consume three to five times more power than indoor. Furthermore, power comes in many different forms. It's a good idea to get a display that comes with a universal power supply of 85V to 265V.
The investment required to implement an outdoor digital signage campaign is not trivial, but don’t be short sighted and only consider the upfront capital costs (CapX). Take the time to find a hardware solution that minimizes the operational costs (OpX). While power costs can be easily calculated once you have the total annual power consumption, the service costs can be more unpredictable. Vandalism, power outages, periodic cleaning, and emergency maintenance can add up to a sizeable chunk of money. The following are specifications you should look for in an outdoor digital display:
• What type of cover/safety glass will be used? It must be able to withstand a beating.
• Glass should be separate from LCD screen. That way you can replace damaged glass without replacing LCD.
• Can the digital display be serviced in the “installed” position? Very important
• How easy is the service considering that repairmen be working in outdoor conditions (cold, rain, wind-blown dust)?
• How modular are the replacement components?
• Can the display be controlled, diagnosed, and updated remotely?
• Can the display report back to the NOC operational data and alerts?
• Can the embedded player, 3G modem and switch be automatically or remotely re-booted?
• How intelligent is the display? Can it verify that the "correct" image is being displayed on the screen?
• Are there provisions for the mini-UPS system so unit can “phone home” if it experiences a failure?
• What is the “sealing” rating of the display? NEMA 3, IP 55, etc.
• How is the unit protected from insects, rodents?
• The glass should have an anti-reflective (AR) coating to reduce reflections from eight percent to under two percent. (AR coating helps with reflections from buildings, cars, and direct sun.)
• Does the paint finish provide protection against harmful UV rays over time?
• What is the overall projected life-cycle of the display? 3 year, 5 years, 10 years? This factors into the ROI model.