Digital Display Technology. Learning the Basics of Digital Signage Chapter 2: The thing about plasmas?
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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Chapter 2: The thing about plasmas
After LCDs, plasma screens make up the second-most popular display choice when it comes to digital signage. Although plasma screens are not the most popular choice among consumers, that doesn’t mean plasma technology is inferior. As you’ll discover quickly over the course of this chapter, plasma screens have their own advantages over LCDs. As with anything else, the performance of the display should be evaluated with regard to the type of application it’s being used for.
Before going any further, let’s examine briefly how plasma technology works. Plasma TVs are similar to LCDs in one respect: Small pixels sandwiched between two layers of gas are heated by electrical current. The end result is that the pixels create colors based on the intensity of the current. There is one significant difference, however: the contents of the pixels. On an LCD, the pixels are filled with liquid crystals. A plasma screen uses gas plasma. That means plasma screens can do without one key component that LCDs require.
The biggest difference between LCD and plasma is the design of the pixels. Photo courtesy of Scala.
“LCD panels need the backlight to create an image because liquid crystals can’t create light,” said an article on the Australian online edition of PCWorld.com. “However, plasmas don’t have a backlight because the process of charging a sub-pixel creates light.”
Now that you understand the basics of how a plasma screen works, we can delve into the types of advantages a plasma screen can bring to the table.
Channeling full motion
Most industry analysts agree that full-motion video appears much more cinematic on a plasma screen than on an LCD. The reason lies in the abovementioned fact that plasmas require no backlight.
“The primary difference is that plasma is what is called an ‘emissive display,’” said Bill Gerba, CEO of Fort Lauderdale, Fla.-based WireSpring Technologies Inc. “Every pixel makes its own light and is sending its own light out. As a consequence, the colors are very vibrant. If a pixel is black, there’s no light coming out of it, so it’s a true black. With LCD, on the other hand, there’s a film that basically makes the different colors, but there’s a backlight behind it. To make black, for example, the pixel gets filled in so that it doesn’t let the light from the backlight pass through. Consequently, the big shortcoming of the LCD is that blacks aren’t as black – colors aren’t as vibrant – as they are on plasmas.”
“The primary difference is that plasma is what is called an ‘emissive display.’ Every pixel makes its own light and is sending its own light out. As a consequence, the colors are very vibrant.” Bill Gerba, CEO of WireSpring Technologies Inc.
Ron Snaidauf, vice president, commercial products, LG Electronics USA, offers an opinion that corroborates Gerba’s.
“Plasmas have a higher contrast ratio, better blacks, better color and overall depth than what you’re going to get with an LCD,” Snaidauf said. “So if you’re going to be doing something where you’re always changing the images and you’re not going to have anything static there, that’s going to be something that a plasma will excel at.”
In addition, plasma screens generally have a higher refresh rate, meaning that they are able to handle fastmoving video better than LCDs. That, plus the added vibrancy and color depth of a plasma screen, generally makes it the top choice of consumers who want to use it simply for in-home entertainment purposes.
“For home theater, many prefer plasma screens,” said Bob House, COO at Tempe, Ariz.-based NORVISION Inc. “The picture is a little better than on LCDs, and fast motion, such as a baseball flying at 100 mph, is clearer. However, LCD technology is catching up fast.”
“Personally, I prefer plasma to LCDs” for home theater purposes, said Jimmy Dun, vice president of business development for Fremont, Calif.- based Dynasign Corp. “In terms of moving video, plasma obviously has much more superior quality in terms of colors and speed. It yields much better video quality.”
Prices and sizes
Another advantage of plasma screens over LCDs is the overall price tag. Recall that in the last chapter, we stated that a 46-inch LCD display may cost $3,000 or more, while a 50-inch plasma screen may run from $2,000 to $2,500. Because plasma screens are easier to manufacture, their cost is lower relative to LCDs. As noted in the previous chapter, that differential is likely to become less significant as LCD technology improves. Plasma screens also are facing growing competition from the LCD market in the area of screen size. Plasmas generally have held a monopoly on screens in sizes greater than 50 inches, but LCDs slowly are making inroads onto that playing field. While the largest digital displays on record are plasma screens, companies are beginning to offer LCD screens in the 52-, 65-, 70- and even 100-inch range, albeit for higher prices.
Beating back the burn-in beast
No technology is completely infallible. There’s a storm cloud to every silver lining and it’s no different for plasma-screens. Like anything else, plasma screen technology has its deficiencies.
As stated in the previous chapter, one area where plasmas come up short is in the realm of static content. While plasmas excel at displaying full-motion video, they are more susceptible to the effects of burn-in than LCDs are.
The reason for that susceptibility lies in the components that make up a plasma screen. According to a fact sheet on the Panasonic Corporation of North America Web site, burn-in is caused by “an uneven aging of the phosphors in a display device.”
As the site explains, actions can be taken to avoid burn-in on a plasma screen.
“Use common sense when it comes to your plasma TV,” the site said. “Don’t pause video games or watch TV stations with station logos onscreen for long periods of time, and use one of the many display calibration DVDs available today for properly setting brightness and contrast. The rule of thumb: If you don’t worry about your traditional tube TV, you don’t have to worry about a Panasonic plasma TV.”
That’s comforting advice for casual TV watchers, but digital signage typically runs for several hours at a stretch — sometimes even 24 hours a day. And in most cases, signage is dealing with at least some static content – usually a considerable amount of it. Digital signage deployers have to pay closer attention to burn-in effects than the typical consumer watching television for the standard two hours a day.
While most experts agree that plasma screens still need to make progress in the area of burn-in mitigation, some proponents of plasma technology argue that plasma screens have come a long way toward minimizing the effects of burn-in.
“Burn-in (or premature aging of the phosphor) was a concern in the first-generation plasmas years ago, but this problem has long since been drastically reduced – particularly now that we’re in the 10th generation of plasma technology,” said Andrew Nelkin, CEO of Secaucus, N.J.- based Panasonic Professional Display Company. “While it’s true that any TV can retain images, plasma is on par with CRTs that were used in the signage business for decades.
” Proponents like Nelkin point to mitigation techniques such as screen savers, pixel shifting and brightness level adjustments as front-line defenses against burn-in.
The reliability factor
Another perceived shortcoming for plasma screens is that they’re not as reliable as LCDs. Some experts argue that plasmas generally have a shorter life span than LCDs and suffer more malfunctions.
“LCD is just a much more dependable, robust technology,” said Ryan Cahoy, vice president of sales and marketing for Toronto-based Rise Vision Inc.
House says his company provides solutions for digital signage systems that use LCDs, as well as those that use plasma screens. But he says he has greater confidence in the longevity of LCDs.
“NORVISION prefers LCD displays due to their low power consumption and long life-cycle,” House said. “Plasma (screens) have their use, too, because of lower cost and larger panel sizes, but reliability is less compared to LCD, and we always sell five-year, onsite extended warranties on plasma panels that are used for critical digital signage systems.”
But some data seems to undercut the perception that plasma screens are less dependable than their digital cousins. A study that appeared in the December 2007 issue of Consumer Reports attempted to determine which digital display type – plasma screen or LCD – experienced more technical issues over a three-year period.
“Consumer Reports found little difference between the average repair rate for LCD and plasma TVs- overall, they both had a 3 percent repair rate,” said a news release issued by Consumer Reports about the study. “Among the tiny percentage of sets with problems, most repairs were free, presumably because they were covered by the manufacturer’s standard warranty. The few respondents who paid out of pocket for repairs spent an average of $264 on LCD sets and $395 on plasma.”
Making the right choice
To summarize what we’ve learned in the past two chapters, the type of display you’ll want to choose for your digital signage system will depend entirely on how that system will be used. Plasma screens and LCDs both are powerful technologies. One is not superior to the other, but they have unique strengths and weaknesses that make them optimum choices for some signage applications, but less appropriate for others.
What are you trying to accomplish with your digital signage system? How will it be used? Is it meant to communicate with consumers? Educate them? Entertain them? How long will content segments be? Will the signage display a lot of static content, or will it mostly be fullmotion video?
Then there’s the environment where the displays will be. Will they be placed in areas with a lot of ambient light (e.g., outdoors), or will they make their homes in dimly lit corners?
As we’ll see in Chapter 4, most experts agree that the technology is not nearly as important as the content. A word of warning: Some deployers walk into a showroom and are completely bowled over by a new and impressive digital display with all sorts of bells and whistles. Eager to include the same features in their own deployments, they’ll fork over copious amounts of cash to purchase the displays, only to discover months later that those same bells and whistles — though still impressive – aren’t helping them convey their message. Worse yet, in some cases, the features may wind up distracting the consumer from the content.
It’s an important lesson learned: Before you spend a single penny on the display – or any component of your digital signage system, for that matter – zero in on the message you plan to send the viewer. Only when you have a grasp of the message will you be able to determine which display type will be the best at conveying it.
With that in mind, there are some general rules to remember when selecting the display. If you plan on using a lot of static content in areas of high ambient light, you’ll likely be better off if you go with an LCD. If full-motion video is a critical part of your presentation – particularly highspeed video – then a plasma screen probably will give you a slight edge.
Of course, there are exceptions to the rule. Just remember: The message is the thing.
To be Continued to Chapter 3:
Earlier Chapter 1: