A common concern raised when discussing outdoor displays is durability. The majority of the external surface area of a display is comprised of glass and most people’s experience with glass is that it’s easy to break. Can the display make it through a heavy hailstorm? What about people bumping into it? How about kicked-up gravel from the road?
These concerns naturally lead to another line of questioning: what do we do if the glass breaks? Do we have to replace the whole screen? How long will that take and how much will it cost?
Having been through this exercise hundreds of times, we’ve taken this whole conversation and turned it into an engineering project. What can we do to make the display glass durable enough for the outdoor environment? If the glass does break, what can we do to design it so that weather integrity is maintained, and it’s super easy to replace without costing a fortune?
Some people might tell you that placing the display in another enclosure is the answer. However, these environmentally sealed boxes actually cause more problems than they fix. One, they diminish the brightness of the display and increase the reflection of ambient light, often making the content dull and difficult to see in outdoor sunlight. Two, they trap solar heat (up to 1250 watts per square meter of enclosure surface area), display heat, electronics heat, and require extreme measures such as air-conditioning or filtered ambient air ingested and blown directly across the electronics and/or optics to keep the unit from overheating. Three, air conditioners generate condensation inside and outside the sign, which is impossible/impractical to manage, shorts out electronics, creates product liability and is unsightly. Air conditioners and/or air filters require regular maintenance, increasing operational expenses. Ultimately, air filters fail to be changed frequently enough and the unit overheats and, at best, shuts down until the filter is changed or more likely the display has a catastrophic failure from excessive heat. Even with the best air filters, moisture and/or fine dust will penetrate the display degrading image performance/quality and/or increasing failure rates. More likely than not, at some point in the units life, the air filter will become plugged, the repair technician will not have a suitable replacement, so the dirty filter gets removed and no replacement is installed. This leads to quick and ultimate death of the display. And four, enclosures are not custom built to fit the frame of the display so they’re often generic and unattractive.
No, we’ve engineered a much better solution.
Ballistic-Resistant Cover Glass
In our production facility we custom cut and optically bond two pieces of anti-reflective glass to create our 13.5mm thick cover glass. The optical adhesive, combined with the specific glass and anti-reflection coatings result in the highest transparency, lowest reflection, and lowest haze display cover glass on the market. This gives the displays not only extreme durability, but also preserves image luminance, contrast, viewing angle and color saturation in any ambient environment. Just to demonstrate how strong this cover glass is, we took some video of one of our engineers wailing on it with a wood beam. Then we took a .22 and unloaded a few rounds on it to see what would happen. Take a look:
Separate LCD and Cover Glass
The LCD cells used on our displays are not bonded or fused to the cover glass. With the glass cover consisting of two layers of glass with plastic resign sandwiched inbetween, in the event the cover glass does actually break, typically only one layer of the glass cracks, sharding does not occur, the cover glass does not become spider webbed (frosted), weather integrity remain intact, and the LCD panel typically remains undamaged. Beyond the obvious benefit of significantly reducing costs on display repair (i.e. the cover glass is readily replaced without removing the display from its installed position, the detached design of the LCD and the cover glass, combined with the LG-MRI patented CoolVu® indirectly extends the life of the LCD panel itself by not only reducing the LCD temperature, but radically reducing the front surface temperature of the glass that can be touched with a bare hand.
In another article we mention just how important it is to keep the LCD cool to prevent solar clearing. A core design element that helps us remove generated heat from in front of the LCD is an air gap between the LCD and the cover glass. The ability to continuously circulate a laminar flow of internal sealed (i.e. no mixing at all with outside air or airborne contaminants), clean, dry air over the LCD and behind the cover glass prevents boiling the liquid crystals and keeps solar clearing at bay. Displays that have LCD’s direct bonded to cover glass can’t effectively remove the heat and just won’t hold up in a sunlit environment. The touch temperatures of direct bonded displays also become excessive and may result in blistered or burned skin if touched. When the cover glass on a direct bonded display becomes scratched, cracked, shattered, the LCD is also typically destroyed. In any event, no field repair is possible and the entire unit must be removed, crated and transported to a suitable repair facility and/or disposed of and replaced by a new unit. In either case, it’s a very disruptive and expensive proposition.
Every LCD display that we build is designed for its operating environment. From our military vehicle background, that means handling vibration, power fluctuation, dirt, dust, and extreme temperatures. For street-side displays, that means being able to handle the abuse of foot traffic, weather, and the occasional vandal. Placing an LCD screen in an outdoor enclosure simply doesn’t compare.
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