Digital Signage: An outdoor reality check

by all | 27 September 2013 8:30 am

By Ralph and Jennifer Idems
As marketers have long recognized the benefits of displaying their messages in public environments, out-of-home (OOH) advertising has grown to become a multi-billion-dollar industry with a far-reaching scope of influence around the world. While static billboards, posters and wall murals have traditionally dominated the OOH landscape, digital signage has rapidly made its mark on the industry in recent years, due to its versatility and eye-catching visuals.

Indoor deployments of digital signage have become ubiquitous, while outdoor installations are less common. Nevertheless, many of the same organizations that have hosted indoor digital signage—including retailers, hospitality venues and the transportation sector—have also recognized the benefits of deploying digital signage outdoors, where it can be seen by more people and bring them in for business to achieve a return on investment (ROI).

The outdoor digital signage market has taken longer to develop than indoor installations because of environmental challenges, including sunlight, variations in temperature, inclement weather, dust and dirt. Today, however, there are many major rollouts of outdoor digital signage networks, as these challenges have been considered and addressed through new technologies.

Indeed, while liquid crystal displays (LCDs) installed indoors and outdoors might look the same to a passerby, they are very different, as the latter need to be specially engineered to prevent failures and to reduce the need for expensive on-site maintenance and service over their life cycle.

Sunlight
While content may not differ much between indoor and outdoor digital signage, the displays must be designed and built differently to accommodate for the environmental factors that can affect screen visibility and legibility. Sunlight is one of the most significant of these factors.

In bright or direct sunlight, as well as in high ambient light conditions, standard indoor LCDs will suffer from fading, washed-out colours and poor performance. To be fully visible to passersby under the harsh light of day, digital signs must be highly illuminated.

Another danger of exposure to sunlight is solar loading or isotropic behaviour. This involves an LCD absorbing to much external heat in conjunction with the internal heat from its backlighting,

leading to the degradation of the display. The screen starts to turn black in certain spots and its overall operating life is reduced.

Outdoor display suppliers generally agree a minimum luminance level of 1,500 cd/m² is required for adequate visibility. High-brightness (HB) screens, which are specially designed to emit more light than standard commercial-grade screens, can provide between 2,000 and 5,000 cd/m², as well as better contrast levels. Ambient light sensors can be installed to automatically adjust a screen’s brightness at different times of day and night, as appropriate.

Most LCDs already feature anti-glare surface treatments to diffuse reflected light from external sources like the sun. When light hits the rough-treated surface, it is reflected away at different angles. This reduces the intensity of the light reflected into the eyes of passersby, but the anti-glare coating also reduces the screen’s effective contrast ratio with a hazier appearance.

One alternative to an anti-glare treatment is an anti-reflective coating, which has a smooth, glossy finish. Instead of diffusing the reflection, it actually reduces the amount of reflected light. These types of coatings are also becoming common on high-end personal computer (PC) screens and mobile phones. They ensure a crystal-clear image, improved colours and a high contrast ratio even under high ambient light conditions.

Upgrade options
The two most common methods for upgrading an LCD for outdoor use by controlling solar loading on the front face, improving visibility and prolonging its useful life are (a) optical bonding and (b) an air curtain.

With optical bonding, the display is modified by using an optical-grade adhesive to bond a sheet of glass to the top surface of an LCD panel. The air gap between the cover glass and the panel is then completely filled with a silicon-based gel or adhesive.

Optical bonding reduces unwanted reflection, glare and mirror images that can make a display difficult to read. In addition to better optical performance, the bonded sheet makes the structure more durable. Parts and service, however, will be more expensive and difficult, since the LCD has been modified and is no longer standard.

An air curtain, on the other hand, is added by creating a gap in front of a screen that allows a constant flow of air. This helps prevent heat from building up due to sunlight or high temperatures. It is also the more cost-effective upgrade, since a standard LCD can be used without any direct modifications. This will make a big difference in reducing total life-cycle costs and in the availability of parts.

Variations in temperature
If an LCD and its enclosure are not rated for extreme temperature fluctuations, they may suffer from screen blackouts, damaged electronics and reduced efficiency. When a display rated for up  to 30 C (86 F), for example, is installed in a region where summer temperatures regularly reach 40 C (100 F), its useful life will be severely diminished.

In Canada, especially, where temperatures vary drastically throughout the year, a display needs to be designed to function in all four seasons. It should be configured to start up properly under both freezing and hot conditions, operating in temperatures ranging from -40 C (-40 F) to 50 C (122 F). Some newer LCDs are even rated to withstand temperatures up to 110 C (230 F) on the front face.

Typically, enhanced LCDs are directly backlit by either light-emitting diodes (LEDs) or cold-cathode fluorescent lamps (CCFLs), which add to power demands and the spread of heat dissipation. LEDs are the preferred option, as they help prevent problems related to solar loading by reducing the internal temperature of the display compared to CCFLs and they remove harmful UV emissions from the illumination system. LEDs also last longer and exhibit minimal brightness reduction over the life of the display.

There are several ways to keep an outdoor digital display’s internal systems cool and thus extend its useful life, including—from lowest to highest efficiency—air conditioners, heat exchangers and direct air cooling systems (DACSs).

Air conditioners use a cooled refrigerant as a medium for thermal exchange, lowering the unit’s internal temperature relative to the external ambient temperature. Compared to the other options, they are noisy, use a lot of power, have many serviceable parts and will not last as long.

A heat exchanger uses aluminum, copper or polyvinyl chloride (PVC) as the cooling surface in a thermal exchange medium.

Finally, a DACS uses ambient air as a cooling medium. It is the most efficient of the three options, consuming minimal power and operating very reliably.

Inclement weather
When installing a digital display outdoors, it is essential to first consider the effects of weather on the unit. Rain, snow, ice, wind and even humidity can have highly detrimental effects on the housing, the screen and the internal electronics.

Rain and snow will corrode the display’s housing if it has not been properly treated and waterproofed. Strong or gale force winds have the potential to damage or even knock over a display. A rugged enclosure for outdoor digital signage should be strong enough to withstand winds up to 241 km/h (150 mph).

It is crucial to investigate local weather patterns before the displays are installed, ensuring products are selected that can withstand harsh regional conditions.

Dust and dirt
Brake fumes, dust and air pollution can also reduce a display’s life cycle by damaging the LCD panel, clogging the air intakes and filters and damaging the electronics housed within the display.

Safety
In addition to environmental factors, safety is another concern with outdoor digital signage deployments. The units must be structurally sound and electrically safe in compliance with local, national and/or international laws.

Ideally, the electronic components used to build the display should be certified by an internationally recognized organization, such as Underwriters Laboratories (UL) or the Canadian Standards Association (CSA).

Security
Beyond windblown debris and other damaging weather conditions, digital signage can also fall victim to deliberate attacks by vandals. This is even the case in supervised locations.

To protect units against vandalism and ensure their longevity outdoors, shatterproof and impact-resistant screens should be installed within tamperproof steel enclosures.

Regulations and permits
Many cities have restrictions that apply to outdoor digital signage, such as bylaws prohibiting the display of full-motion video toward vehicular traffic and codes requiring screens to be dimmed or shut off at certain times of day.

By ensuring they use products and systems that comply with these local rules, digital signage installers are more likely to acquire all necessary permits, certifications and other legal documents with ease.

Power
Operators of outdoor digital signage will need to investigate their power supply options thoroughly before installation. The total cost of ownership (TCO) will depend on the displays’ power requirements, where the power comes from and how the cost of that power is being covered (i.e. by one or multiple parties). It is imperative to establish these conditions early in the process, so as to avoid confusion down the line.

Power is also an important consideration after the installation, as it may be necessary to monitor to show other parties how the unit is receiving power, how ‘clean’ that power is and whether or not the unit is also pulling power from other sources.

For the operator, it is important to track what happens during power fluctuations and whether or not the unit will shut down and reboot gracefully during an outage. Among the most embarrassing fates for outdoor digital signage, but not entirely uncommon sights, are the startup screen and the dreaded ‘blue screen of death,’ so operators should have a plan in place to cope with outages.

Monitoring
In addition to monitoring power use and responses to outages, operators will need to remotely monitor their outdoor digital signage’s on-screen content, to ensure it is always appropriate. The display can connect through a wireless network to remote computers where the operator can adjust content.

Further, new developments in monitoring are allowing digital signage operators to fix problems as they arise, without needing to send a technician to the specific installation site, thus reducing service and maintenance costs over the unit’s lifetime. Some remote monitoring systems can even predict possible failures, allowing for pre-emptive service.

Outdoor digital signage units can be expensive and difficult to access for maintenance purposes, so any measures to improve their reliability and ease of service will be worthwhile.

Dramatic advances
The technologies that enable digital signage to be installed and operated effectively outdoors have advanced dramatically in the last few years. The displays themselves have become more reliable and cost-effective, with a wider range of capabilities and options available. Manufacturers have introduced larger screens, multi-touch interactivity, integrated speakers, microphones, cameras, other peripheral devices and systems for remotely monitoring a network of digital signs from a central location.

As digital signs are deployed for more purposes, from marketing and advertising to wayfinding, public engagement, information, menu display and amusement, it is important to select the right technologies to ensure a trouble-free outdoor deployment.

Ralph and Jennifer Idems are co-founder and administrative assistant, respectively, of Toronto-based Vertigo Digital Displays, which designs and engineers indoor, outdoor and semi-outdoor digital signage units. For more information, visit www.vertigodisplays.com[6].

Source URL: https://www.signmedia.ca/an-outdoor-reality-check-2/

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