TV: LCD vs. DLP vs. plasma

An high-definition TV is a big-ticket item, so it's no wonder buyers are still very concerned with performance issues such as rainbow effect and burn-in. But before settling on an LCD rear-projection set, here are a few things to consider.

First, you need to decide whether you want a microdisplay (also known as a rear-projection set) or a flat panel, such as a plasma or LCD TV. There are three basic types of rear-projections: LCD (liquid-crystal display), DLP (digital light processing), and LCoS (liquid crystal on silicon).

Rear-projections are thinner and lighter than the CRT rear-projection sets that are still kicking around, but for the most part, you still can't hang a microdisplay on the wall. By contrast, you can easily hang a plasma or LCD TV on the wall, but they are not widely available in very large sizes, and they cost significantly more, inch for inch. Each type of microdisplay has its pros and cons, but they all use a lamp that needs to be replaced every few years, so that shouldn't be a factor.

The rainbow effect you mention has been an issue specifically with DLP rear-projection sets, which use a colour wheel to create red, green, and blue. Some viewers can see streaks of colour on DLP TVs, especially when moving their eyes across the screen. Newer and faster color wheels, however, have significantly reduced the rainbow effect, and most people never see it at all. Furthermore, DLP has some performance advantages over competing technologies, including the deepest black levels of any projection technology (though LCD is coming on strong) and high resolution chips that show every pixel of high-definition sources.

As far as plasma TVs go, that danger of burn-in has been greatly exaggerated. Burn-in occurs when a relatively static image such as a stock ticker, a network logo, or a letterbox bar gets etched permanently onto the screen. The potential for burn-in is greatest during the first 100 or so hours of use, during which time you should keep contrast rather low (less than 50 percent) and avoid showing static images or letterbox bars on the screen for hours at a time. After this initial phase, plasma should be as durable as any television technology. Many panels also have burn-in-reduction features, such as screensavers and pixel orbiting. Under normal viewing conditions, you should have nothing to worry about.