Chapter 1: What is LCD technology?

Digital Display Technology. Learning the Basics of Digital Signage Chapter 1: What is LCD technology?

 INSIDE: Digital signage is emerging rapidly as a viable and effective communications tool. With that in mind, companies taking the first step in signage deployment will be much more successful on the playing field if they understand the basics of what digital media is and how it operates. For a crash course in digital signage, read on.

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Published by NetWorld Alliance

 © 2009
All photos courtesy of LG Electronics Inc. unless otherwise specified.
Written and edited by Travis K. Kircher, editor,

Dick Good, CEO
Tom Harper, President and Publisher
Bob Fincher, Executive Vice President and General Manager, Technology Division
Joseph Grove, Vice President and Associate Publisher


Introduction Signage 101


Imagine it’s the first week in September and you’re taking your 5-year-old son chili dog in hand to his first college football game. It’s a special moment for your child. He’s heard about football all of his life, usually from enthusiastic cousins who eagerly recount stories of exciting plays, last-minute touchdowns and bone-crunching tackles that left fans screaming in their seats. He’s even seen a few games on television. Today will be the first time he’s ever experienced a game live in the stands. Football fan that you are, you can’t wait to enthrall him with your moment-by-moment commentary explaining the various plays and strategies.

But by the end of the second quarter, you’re ready to leave the stands and demand a refund.

It soon becomes obvious that the home team needs some serious help. Not only are they bad players in general, but they don’t even seem to understand the basic rules of football

Travis K. Kircher,
Self and
Digital Signage

"You can’t compete effectively if you don’t understand the rules of the game. That goes for sports, business and, not surprisingly, digital signage deployments."


As soon as the quarterback gets his hands on the ball, he hugs it and starts running toward his own team’s end zone instead of his opponent’s. Even worse, his teammates tackle him and dance victoriously when the ball is yanked from his arms. When the opposing team’s quarterback catches the ball, the home team makes it a point to tackle every other player but the quarterback. The game is an absolute disaster and, ultimately, a waste of money. It’s an important lesson learned: You can’t compete effectively if you don’t understand the rules of the game. That goes for sports, business and, not surprisingly, digital signage deployments.

It’s no secret in today’s business landscape that digital signage is emerging rapidly as one of the most effective and eye-catching communications mediums on the market.
Spend time with any marketing professional and you’ll quickly feel the excitement generated around digital technology. The enthusiasm is electric. Convinced by the vibrant colors and sharp resolution that a digital display provides, your CEO is ready to deploy dozens of displays under your company’s banner.

But before you sign on the dotted line and roll out the cash, you need to understand exactly what digital signage is and how it works. What kind of display will best meet your needs: plasma or LCD? What are the pros and cons of each? How will digital
technology change in the next five, 10 or 20 years? What about terminology - what is the language of digital technology?

Far too many signage deployers - like the confused football players - launch a huge  project without having a firm grasp on the basics. More often than not, these misguided efforts wind up costing the deployer lots in terms of sunk cost. This is unfortunate, particularly when the mistakes could have been avoided had the deployer only taken the time to learn some basic facts about the business.

That’s what this guide is about. By the time you’ve finished reading, you’ll understand enough to know where digital signage has been and where it’s going. You’ll also know how to make smart purchasing decisions when it comes to your display. Think of it as
Digital Signage 101.

We’d like to thank LG Electronics Inc., whose kind sponsorship of this guide enables us to bring it to you at no cost.


Chapter 1:  What is LCD technology?











In a color LCD panel, each pixel is made up of three liquid crystal cells. Light passing through the filtered cells creates the colors seen on the LCD.
Photo courtesy  of ADFLOW.

Before we get into the various types of digital displays on the market, it probably would be advantageous for us to define exactly what we mean by the phrase “digital signage.”

Digital signage is a form of out-of home advertising that appears on some type of digital display — most often a plasma screen or LCD. The type of content on the signage can vary. It may take the form of colorful slides that are flashed on the screen in 10-second intervals. It may be a list of text that is updated regularly, such as a roster of arriving or departing flights displayed in an airport lobby. The content can consist of scrolling stock prices, a live CNN news feed or even dramatic, full-motion video.

Whatever the content, the purpose of digital signage is the same: It’s trying to communicate something to the viewer. Digital signage is not just a flashy way for the consumer to “watch TV.” It educates, sells a product or conveys an idea.

A digital signage system generally consists of a number of components. The first component is the hardware, which is made up of the display (again, typically an LCD or plasma screen) and some sort of signage  player device that stores the content and feeds it to the display. Then there’s the software - the set of instructions that governs the entire system. The network - the final component - is optional but highly recommended, especially for large-scale signage deployments that cover a wide area that might include multiple cities, states or even continents. A network is an effective empowerment tool that enables deployers to remotely manage their digital displays without leaving the office. Signage content can be replaced, deleted or updated at the click of a mouse. When individual displays malfunction, alerts can be sent automatically to the network administrator, prompting the deployer to conduct a remote diagnostic (and sometimes repair the display) from hundreds of miles away.

That’s the basis of digital signage in a nutshell.

The first questions that might be running through your mind - and the mind of any prospective signage deployer — likely revolve around the display itself. After all, the digital display is the most visible and dramatically striking component of the whole ensemble. It’s the coolest to look at. It also - in most cases - represents the most significant portion of the initial investment.


“LCDs are the display of choice if you plan on featuring a lot of static content … with an LCD, you’re not going to have the image burn that you would see on a plasma.” Ron Snaidauf, vice president, commercial products, LG Electronics USA


Faced with a choice between two displays, which way should deployers go? Do they want to purchase an LCD or a plasma display? That’s the question we’ll examine in the next two chapters. In the first chapter, we’ll take a close look at LCD technology to determine its strengths and weaknesses.


How it works

Even if you’ve never heard of LCDs - or liquid crystal displays - chances are you use them on a regular basis. They’re featured in a wide variety of products, from laptop computers to cell phones to GPS devices. Within the past five years, LCDs have emerged as a viable option for digital signage deployers. So how do they work? One of the primary components of LCDs are - not surprisingly - liquid crystals. According to an article on, liquid crystals are “liquid chemicals whose molecules can be aligned precisely when subjected to electrical fields - much in the way metal shavings line up in the field of a magnet. When properly aligned, the liquid crystals allow light to pass through.”

An LCD consists of a fluorescent light - or backlight - that shines through a layer of liquid crystals located in pixels sandwiched between two polarized filters. When electrical current
is applied to the liquid crystals at various currents, they combine with colored filters to make an image.

“In a color LCD panel, each pixel is made up of three liquid crystal cells,” the article said. “Each of those three cells is fronted by a red, green or blue filter. Light passing through the filtered cells creates the colors you see on the LCD. Occasionally the mechanism that sends the electrical current to one or more pixels fails; in those instances you’ll see a completely dark, ‘bad’ pixel.”


Static content

By now you should have a basic understanding of the inner workings of a liquid crystal display. Now that you can grasp some of the technical aspects, it’s important to recognize
both the benefits and the limitations of the technology. In what cases are LCDs superior to plasma? Where do they fall short? Only when you fully understand how LCDs perform in the real world will you be able to determine if an LCD is right for your purposes.

When purchasing a digital display, one of the first terms one needs to come to grips with is “burn-in.”

Burn-in - also referred to as “image retention,” “ghosting” and “image shadowing” - is the dreaded phrase that no digital signage operator wants to hear. It usually occurs on displays
that continuously run static content, such as logos, banners, crawling text and similar graphics that remain on the screen for long periods of time. When the picture changes and the static content is removed, a faint “ghost” or “shadow” of the content may remain. If you’ve ever used a desktop computer, you’re probably familiar with screensavers. Shortly
after desktop computers became popular, screensavers were developedin an effort to curb the effects of burn-in by directing the computer to replace static content with animated moving content when a monitor had been idle for a pre-specified period of time.

Burn-in not only can be distracting, but it can also decrease the effectiveness of your digital  signage. Signage is supposed to draw the eye because it is clear, sharp and brilliant. No one wants to look at a display that is difficult to read because it’s still displaying the faint traces of last week’s stock performances. That’s why it’s vital that signage deployers avoid burn-in at all costs.

Burn-in typically affects any phosphor- based monitor or display, including cathode ray tubes (CRTs) and - particularly of interest to those who plan on deploying digital signage - plasma screens.

LCDs, on the other hand, are much more effective at avoiding the effects
of burn-in.

“LCDs are the display of choice if you plan on featuring a lot of static content,” said Ron Snaidauf, vice president, commercial products, LG Electronics USA. “Corporate logos,
crawls featuring stock performances, lists of arriving or departing flights - all of these are examples of static content that can create significant burn-in issues. With an LCD, you’re
not going to have the image burn that you would see on a plasma.”

Bill Gerba, CEO of Fort Lauderdale, Fla.-based Wirespring Technologies Inc., agrees.

“(LCDs) don’t have any kind of burnin problem,” Gerba said. “A plasma is kind of like a CRT. If you leave the same image on the screen for a while, it has the potential to burn in. You get a ghosted image any time you try to show something else. LCD doesn’t suffer that.”


Smaller screen sizes

Whether you’re watching television, working on a computer or staring at a digital display, screen size is important. The general perception (though for business and logistics reasons this is not always the case) is that bigger is better, but there is a wide variety of choices when it comes to size. A digital screen can be as small as a 1.25-inch mobile-phone display or as large as a 108-inch plasma screen.

In the past, LCDs have been characterized as the display of choice when smaller screen sizes are required.

“With LCD, you’re going to have smaller screen sizes than what you would get with a plasma,” Snaidauf said. “If you wanted something with a screen size lower than 20 or 30 inches, you’re going to see that an LCD will fit the bill where plasma technologies don’t exist.”

Conversely, plasma displays traditionally have prevailed when it comes to large screen sizes.

“The plasma guys are trying to go bigger because they still have an edge there on the very large displays,” said Sean Moran, president of the Out of Home Media Networks business unit in the Technicolor services division of Paris-based Thomson.

But the plasma screen monopoly may not last forever. Moran says he is witnessing a gradual increase in LCD screen sizes; in fact, he recently attended a conference where a 100- inch LCD was showcased.

“Of course these are in small quantities, but if they’re going there, I think they’re probably going to take this market away,” Moran said. “So that’s had a real negative impact on the plasma program.”


Price tags

One significant downside to choosing LCDs historically has been cost. As a general rule, LCDs are more expensive than plasma screens. As Scott Koller, senior vice president of sales and marketing for Minneapolis, Minn.- based Wireless Ronin Technologies Inc. says, much of the expense stems from the quality-control measures necessary to ensure that reliable LCDs are rolling off the assembly line.

“There was an awful lot of fallout in the manufacturing process,” Koller said. “They have issues with moving the glass through the manufacturing process and coming out of it without losing the quality of the product, so it was more expensive to make.”

According to an article that appeared on in June 2007, a 46-inch LCD display with a good record of reliability likely will cost at least $3,000, while a 50-inch plasma screen from an established brand may run $2,000 to $2,500.

But experts say improvements in the manufacturing process, combined with an increasing number of LCDs on the market, gradually is driving down the price of LCDs to become more competitive with plasma screens.

“Originally, the only flat-screen technology for large screens was plasma, so there was no choice,” Gerba said. “If you were doing a big in-store project, you were going to be using plasma screens. Then LCD came on the market, but it was  incredibly expensive; it might be two or three times the cost of a plasma.”

But as consumer interest in LCD picked up, the manufacturing capacity increased dramatically.

“It dropped the price and, all of a sudden, you were at a point where LCDs were coming much closer in price to plasma screens,” Gerba said. “So all of a sudden their advantages - namely the longer lifetime and the lack of any kind of burn-in potential - started to make them a more clear choice for any kind of digital signage.”

The cost differentiation between plasmas and LCDs has almost disappeared, Koller says.


An LCD market?

Experts say the gradual drop in cost has resulted in a market that leans heavily toward LCDs. Ryan Cahoy, vice president of sales and marketing for Toronto-based Rise Vision Inc., estimates that 95 percent of the digital signage projects his company installs in financial institutions or universities use LCDs rather than plasma screens.

“The prices have come down a lot,” Cahoy said. “Where you’re doing more static-type content, LCD is what we call a much more durable technology.”

Koller takes an even stronger stance.

“We will probably never quote a plasma,” Koller said. “We haven’t quoted a plasma in a year. Unless a client wants something above 46 or 50 inches, which is as high as LCD goes, we won’t quote a plasma.”

But Snaidauf takes a more moderate approach. In the complex competitive landscape, he says he feels there is room for both display types.

“We honestly see a lot of people using both technologies,” Snaidauf said. “When you look at some of the market projections from the research companies regarding the use of plasma screens in the commercial market space, plasma has rebounded in the past couple of months. Cost is still a factor for LCD over plasma, so a lot of people, because of that cost difference, will continue to use plasma even though they are aware of the risks. But for most signage, I think the trend is moving more toward people going with LCD.”


Applications for LCDs

So when it comes right down to it, what specific applications make the best fit for LCDs?

Given the absence of any  significant burn-in issues relative to plasma screens, it’s advantageous to remember this rule: If you plan on including static content on your digital displays, it’s probably best to use LCDs. One example of such an application would be a digital menu board in a fast-food restaurant. Such a menuboard might hang over the cashier stations and list the individual food items offered, along with the prices of those items. Although prices may change from time to time and the individual  items listed might change as the restaurant customizes its advertising for different meals, the rows of text likely will appear in the same general areas. After several weeks, this is likely to create a burn-in issue for plasma screens. In this instance, an LCD would be a better fit.

That’s one example of static content that could damage a plasma screen over time. Other examples include flight schedules on airport displays, team listings on digital scoreboards, financial tickers, news crawls and company logos that remain on the display at all times.

Another important application where LCDs trump plasma screens is for digital displays in fast-food drivethru lanes. In areas of high ambient light, the image from a plasma screen typically will get washed out. Ambient light - such as direct sunlight in the outdoors - also has a tendency to create a reflective glare on the front of plasma screens. LCDs avoid this
problem because they are considered emissive displays, meaning that they use a fluorescent backlight to operate.

As a general rule, LCDs have a greater longevity, are lighter and are able to handle static content better than plasma screens. But as we’ll see in the next chapter, plasma screens have their own unique advantages.

To be Continued to Chapter 2: