This article originally published in Self-Service World magazine, February 2007.
 |
| Plasma screens, such as this one used in the recent New York Times Square JC Penney pop-up store, have been the more affordable screen, but this is changing. |
A glimpse under the hood
LCD displays comprise of two sheets of transparent, polarized material. One of these sheets is treated with a polymer coating that contains tiny liquid crystals. As electric current is passed through the grid, the crystals interpret the current and either allow or disallow light to pass through. Behind the crystals is an array of fluorescent tubes — this is the light that actually passes through the crystals and out to the viewer. Since the crystals themselves don't emit any light, this is called a "non-emissive" technology; it requires relatively little electricity.
Plasma units, on the other hand, use glass that is coated with millions of tiny bubbles containing ionized gas in three sub compartments — red, green and blue. The glass is then treated with a phosphorescent coating. When electric current passes through the plasma, it gives off ultraviolet rays, which pass through the phosphor coating to show the appropriate color.
So which is best?
Although both technologies have their uses, most experts agree that LCD is the right choice for
digital signage most of the time. LCD displays have a lifecycle roughly twice that of their plasma equivalents; they have no issues with burn-in, a serious problem with plasma; they weigh much less than their plasma equivalents; and power consumption is lower.
 |
| Developments in LCD screen technology are eroding plasma's reputation as the leader in video image quality. LCD's digital signage advantages include a longer lifecycle, lighter weight and lower power consumption than plasma. |
Until recently, price has been a primary decision-maker: Plasmas have been the more affordable option, but this is changing as large-format LCD screens come down in price dramatically.
Brad Gleeson, vice president of business development for Planar Systems, said plasma gives better display quality when it comes to video images and fast motion. Plasma screens also are available in larger sizes — but even this is changing, as LCDs are increasingly available in large sizes (50 inches and above).
Still, there are niches where plasma remains the clearly better choice. Mike Abbott, vice president of ADFLOW Networks, said plasma makes sense in multipanel arrays, where cost is the driving factor. Bill Gerba of WireSpring Technologies said plasma is the way to go when the display size needed is somewhere between 50 inches and 80 inches — anything below that range would be a good candidate for LCD, while anything above it calls for a projection system.
