Plasma or LCD ?

Plasma or LCD ?
To the uninitiated the choice between Plasma and LCD can be a confusing one. InAVate aims to cut through the hype and help you make the right choice

There are two, competing flat panel technologies in the market today, Plasma and LCD. A lot of hype and hearsay surrounds both as to their relative merits. For the less well informed this can lead to confusion, and even to the wrong choice of display technology.

The aim of this article is to hear both sides of the argument, if indeed there is an argument to be had between them.

Alan Hemson is Samsung’s product marketing manager, and he offered the company’s stand point on the situation.

“Samsung produce both plasma and LCD products. Our largest LCD at the moment is 46 inches and above that in plasma we do 50 inches and 63 inches. We do intend, next year, to introduce a larger, probably 57 inches, LCD. That’s where the market is headed. Despite this size differential, we generally distinguish between the two technologies based on application.

“We operate in a lot of different markets from education, through airports, digital signage type applications, meeting rooms as well. There are some definite dividing lines beginning to emerge.

“For example, the majority of airports we talk to are insisting on LCD because of the burn in issue.”

For the uninitiated burn in is an effect whereby a plasma (or old CRT) display that shows the same static image for a long period of time can develop fatigue which leads to that image being “burnt in” to the screen.

James Atkins, of LG Electronics, explained the phenomenon. “People are wary of plasma because of burn in and sometimes I speak to people, who seem to be under the impression that if they leave something on the display for more than five minutes at a time, then it’s going to get burn in. But the reality is that to get something to burn in you’d have to leave it there a very extended period of time. And these days it happens no more than it used to on an old CRT. Admittedly the first generation of plasma screens suffered from it probably more than CRTs did, or at least faster. Now the displays are better and we have methods in place to alleviate it, or prevent it from becoming an issue.”

The reason that Alan’s airport clients are so concerned is that things like flight information are often displayed on the same layout twenty four hours a day seven days a week.

“When we talk to these customers it’s always burn in that’s the issue, not brightness, or response times or performance, but whether they will need to replace the screens before time. We have some customers who initially want plasma products but once we talk to them about burn in, and also simple things like the warranty, they change their minds.

“We give a two year warranty as standard on plasma and three years on an LCD. It’s driven by reliability and expected life of the units.”

However, LCD isn’t always the best solution in all situations. All the manufacturers who sell both technologies have a cut off point where LCD stops and plasma starts. So if you want a large display, say 60” or more, you have to buy plasma. And certainly plasma screens are available in larger sizes. Panasonic have a 103” product in the offing.

But why is there a size division at all? Even if the different technologies are useful for different applications, why can’t we simply have 15” plasma displays and 103” LCDs.

The short answer is a combination of technology and economics. It’s not currently possible to make a plasma display that small, and it’s far too expensive at the moment to make a 70” LCD. It’s likely that advances in production techniques will make larger LCD displays cheaper but, at the moment, if you have a couple of similar sized displays around the 40 inch mark the LCD is likely to cost you between 40 and 50% more than it’s plasma counterpart.

Alan Hemson cites another bone of contention. “There’s a feeling amongst some people, particularly AV guys, that plasma is better for video. My personal view is that LCD is catching up very quickly on this. Plasma screens also give better ‘blacks’ as opposed to LCD screens, but that’s often more about the ambient lighting conditions than the display itself.”

On the subject of lighting conditions, Pioneer’s Product Manager Jim Catcheside commented:
“When it actually comes down to picture differences, LCD is very good in very, very brightly lit conditions. Where plasma scores, is that it doesn’t rely on back lighting or illumination. If you look at an LCD in a show room under bright light, it looks fantastic, but if you watch something on it in low lighting conditions then suddenly all your blacks wash out. Conversely plasma can suffer the same problem is bright lighting conditions. LCD is therefore often popular in superstores and other brightly lit environments.”

The other factor than can affect visual performance of the flat displays is response time. This is characterised usually as the time it takes a display pixel to turn from black to white, although some companies will quote a grey to grey transition. Differences in response time are particularly evident in content that has a lot of movement, such as video. Traditionally plasma has had the edge in this area, although as Hemson and Catcheside both stated, LCD has made great strides in this respect. Unfortunately for LCD proponents, plasma technology is still getting faster as well. The time difference may only be measured in milliseconds, but the human eye is a sensitive beast and more than capable of spotting it.

Catcheside also notes that another criticism levelled at plasma is that it is more power hungry and less efficient than LCD. “We’ve done a lot of research into this claim to prove that it simply isn’t true. LCD has a continuous emission from its back light, whereas the plasma is only lighting the required pixels. If you average the use out over the lifetime of the display there is really nothing in it.”

In commercial use, such as in airports or other public display applications, robustness and life span is clearly an issue for either technology. LG’s James Atkins believes that there is very little to choose between the two

“In terms of longevity and durability the two are similar. We wouldn’t say that one is more durable or longer lasting than the other. The standard time we quote for both plasma or LCD is 60,000 running hours.”

However, Samsung’s Hemson disagrees. “LCD is generally more durable for an outdoor application, and also has a longer life expectancy than plasma.”

So where does this all leave the installer? Largely, exactly where we left off, with a decision to make. But hopefully a more informed decision. As with many competing technologies these days it’s a question of horses for courses.

At the current time, if you need a display that’s fifty or sixty inches in size you are left with little choice but plasma. And if you’re looking at something smaller than about 35-37” then LCD is likely to be your only option.

However, in the middle ground the choice then becomes more complex. Ultimately it’s a decision based on what type content your display is to be used for and also how important the quality of the image is. If the screen is to be used to show video or other fast moving content, in a situation such as a board room, where lighting levels can be controlled, then plasma still provides a better response time, and a much more attractive price point.

On the other hand, content that’s to be static for a long time where burn in is a real risk, or displayed in very bright conditions may well be better displayed on an LCD. Information screens in airports or railway stations are a case in point. In-store digital signage is another good example, where high ambient lighting could cause problems.

However, a lot of the time, things come down to budget. Despite advances in the technology, LCD panels are still, size for size, more expensive than plasma. Whilst some will tell you plasma is on the way out, such people should be ignored. Both technologies have considerable headroom for development, more so plasma, since it is in fact the younger of the two.

Neil Colquhoun Channel Business Manager for Panasonic summarises: “The fundamental trade off is that you offset the benefits of picture quality against the benefits of small size, but if you said to me 50” plasma or 50” LCD, I’d say that there was no contest. Plasma is still the best choice.”

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