Feature Story

The Bright Side: The Evolution of Digital Displays for Outdoor Use

A Close Look at LCD and ePaper Trends, Challenges & Future Uses

The evolution of outdoor digital displays continues to transform cities around the globe, and change the way we interact – from transportation to retail shops, hospitality, real estate, construction, education, and entertainment.

Increasingly, we are seeing digital outdoor displays such as signs on buildings, train stations, bus stops, parking meters, gas stations, and ATMs. In the past couple of decades, large-format LED displays have dominated outdoor display applications. Two display technologies that have begun to grow significantly for outdoor use are LCD (liquid crystal display) and ePaper. Below, we look at the growth and innovation of both, as well as design and function challenges, and what to expect in the future.

LCD

Over the last 20 years, the cost of LCD displays has significantly dropped, allowing the technology to be incorporated into many devices we rely on today, such as tablets and mobile phones. For outdoor use, LCD technology, once primarily used for indoor TV, has expanded into outdoor displays for everything from environmental monitoring information to air quality detection, weather forecasting, advertisement, product showcase, information displays, and more.

Industries across the globe continue to find innovative outdoor uses for this modern digital signage technology, which has become lighter, brighter, and provides higher resolution. It’s not surprising that LCD is the most impactful and successful in display technology history, boasting about 80% of the global market, tallying $100 billion, albeit over 95% used indoors.

While LCD technology is more widely used for outdoor displays, there are still some improvements that need to be made. While newer LCDs use power-efficient LED backlight technology, outdoor displays still require a lot of power for the backlight to fight the sun. I’m happy to say that there is a lot of effort in the industry right now to redesign LCD technology to further reduce power consumption. But the fact is, it’s really hard to make displays work well outdoors and those companies that do a good job have benefitted in various sub-market segments.

Challenges faced by LCD for outdoor use include:

Enduring high-temperature variations – From Wisconsin winters (I worked for a pioneering LCD company out of Lake Mills, Wis., and it’s bitterly cold there) to Arizona summers (I was GM for a display company out of Phoenix and hot is not the word), incorporating LCD technology into an outdoor setting can be quite challenging. That’s because LCDs have complicated temperature-influenced performance; they need to be designed to work well in various temperatures and weather conditions. For example, if you have an outdoor LCD display in Arizona, in the summer, the liquid crystal will tend towards liquid and as it does, it loses contrast rapidly. In the winter, in freezing temps, the liquid crystal will tend towards crystal, which means the display will be as slow as molasses. Imagine a gas pump where all the digits look like 8s – the display just can’t refresh fast enough. But there is a way to keep the LCDs comfortable, sort of like what we do for humans –when it’s hot, fans come in handy, but the air filters can clog, and you don’t want to circulate gasoline fumes thru a super-hot display, so a better method is heat sinks and internal system-wide heat distribution. Similarly, when it’s cold, heaters in the form of ITO (Indium Tin Oxide – transparent conductors) directly on the glass helps keep the LCD within a reasonable temperature range. These designs are non-trivial and not for the novice display designer; the designs call for mechanical integrity together with temperature sensing and management to maintain the display within the system in optimum operating conditions.
Enduring direct sunlight –For LCD outdoor displays, there is a big difference between being in the shade, beneath an awning versus in direct sunlight. The reflection, glare, and brightness of the sun can take their toll on an LCD outdoor display. To help solve this challenge, some manufacturers use anti-glare coatings or anti-reflection materials. From films to coatings to cover glass, they all help, but the key to success is finding the right balance between protecting against the sun’s radiation without dimming the display via films/coatings which in turn means that the backlight must be cranked up and that will generate more heat that is undesirable.
Withstanding dust, dirt, moisture, and pressurized water and corrosives – Having an outdoor LCD display, let’s say, at a street corner, can be a bit of a challenge. For one, it attracts dust and dirt from the road, and despite the roof, the rain can still be swept onto the display by winds, gasoline fumes, and other chemicals, which can erode the surfaces and the electronics beneath. To protect these types of displays, many manufacturers include an ip65 rated enclosure that can withstand and protect the display.
Able to run 24/7 in these conditions – Battling all the above elements can take its toll on outdoor LCDs, creating the need to replace and/or maintain them more frequently. Many of these applications require 24/7 operations for years, think billboards, train station displays, street corner signage, etc. that are under 10 years contract and need to run continuously for that period. However, there are some panel manufacturers who are creating rugged components that will expand the lifespan of outdoor LCDs, including building rugged panels to reduce the dependence on heaters or fans. Creating modular structures makes it easier to service and maintain the installations, and typically the larger installs are monitored remotely to provide malfunction alerts so they can be repaired quickly.

So, what’s in store for outdoor LCDs in the future? My general thought is LCD will eventually be replaced by other display technologies, but we will see more improvements and uses before that happens. LCDs will continue to become thinner, consume less power. And the cost will drop even more. You would have never dreamed of implanting LCD technology on a T-shirt or shopping bag, but as the price comes down, that could be a possibility. Just imagine a small LCD showcasing something unique about you on a baseball hat.

While the amount of outdoor LCDs is growing and how we use them is constantly evolving, the technology needs to continue to improve to keep hold of a strong market share. LCD has one of the best features that the consumers – OEMs, city planners, signage companies (except perhaps the panel makers) – love; it’s the lowest cost display technology that is widely available from dozens of manufacturers in hundreds of diagonal sizes. I’m excited about what the industry will come up with next.

ePaper

While outdoor LCD technology still leads the outdoor display industry, ePaper is beginning to have its day in the sun, so to speak. And with good reason. ePaper uses a dual pigment electrophoretic display used in reading applications such as the Amazon Kindle. Low power and paper-like appearance make this technology valuable.

ePaper is also becoming quite popular for outdoor applications like bus stops, airports, and train stations in cities around the globe, which tell you arrival and departure information. Retail is even starting to showcase some unique uses of ePaper, especially during the COVID pandemic, such as counting the number of people in a store.

ePaper is a “green” technology, mainly sipping power from solar panels. Another tremendous advantage of ePaper is it’s a reflective display — the brighter the sun, the better the display. In contrast, with LCD, the brighter the sun, the harder the system must work for you to see.

While ePaper has been widely used for indoor applications like shelf labels, I envision the technology becoming more popular in outdoor settings, such as signage for theme parks and in outdoor kiosks. Most outdoor signage at zoos is static and can’t be updated in real-time. ePaper changes the game by allowing zoo and park operators to wirelessly and easily update signs for an exhibit, for example.

ePaper will also most likely become the “de facto” outdoor display choice during emergencies. For example, when the Fukushima earthquake hit Japan in March 2011, most outdoor digital displays were ordered to be shut down. The only displays allowed to operate were ePaper, which city leaders used to communicate with their citizens. I see this becoming the norm for all cities, not just to communicate to the public during emergencies but also for relaying other important messages, such as for public health. And, as we continue to go more “green,” cities and other organizations will choose ePaper over other display technologies that are considered power hogs.

As the industry moves more toward ePaper technology for outdoor displays, we must keep the following challenges in mind:

Currently, ePaper doesn’t depict color as vividly which restricts product advertisements that make up the bulk of the revenue in some settings.
It can’t quite do video which again means you are limited to showing static information or slower-moving pages.

And it’s offered by far fewer companies in much narrower size choices thus making them at least twice as expensive as LCD.

Conclusion

While both LCD and ePaper technologies for outdoor use are growing, traditional large-format LED signs will continue to be replaced. LCD itself could eventually be replaced by MicroLED, but that’s for another discussion in the future. For the foreseeable future, the growing market for outdoor displays will offer billions of dollars of market opportunity for LCD and ePaper while attracting investments into newer display technologies.

Sri Peruvemba is CEO of Marketer International Inc. in California. He has also served on the Executive Board and was former Chair of Marketing for many years for the Society for Information Display (SID’s Display Week 2022 will be held in San Jose, CA, May 8-13, 2022). With over 30 years of experience in the technology industry, Peruvemba has been an influential advocate in the advancement of electronic hardware technologies. He is an acknowledged expert on sensors, electronic displays, haptics, touch screens, electronic materials, and related technologies; and consults, writes, and presents on those subjects globally. Contact Mr. Peruvemba at sri@miinc.co.

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