TV Technology Overview

Rear Projection TV

Rear-projection television
Rear-projection HDTVs still offer the biggest screen for your buck, although falling prices among big-screen plasmas – 58 inches and up – are forcing RPTV makers to cut prices on their own. It’s pretty obvious, in fact, that eventually RPTVs will go the way of the dodo as flat-panel HDTVs take over completely, but we’re still a couple years away from that. Rear-projection sets start at a sizeable 50 inches and go up from there. RPTV utilizes digital light projection or DLP technology that is driven by a lamp that bounces light through an assembly that produces color and then projects it onto the big screen. Upside for Rear-projection television is less-expensive at very large screen sizes than plasma or LCD TV, and able to produce good black-level performance on certain best models. The only downside is the lamp requires periodic replacement, thicker and bulkier than flat-panels, rainbow effects (on the projected light beam), less impressive off-angle performance than plasma and LCD televisions.

The lamps inside these sets, which cost $200 and more, must be replaced every 3,000 to 6,000 hours (around 2 years operating with ~8 hours per day), depending on conditions of use and users can replace most lamp assemblies on their own. The lamps take from 20 seconds to a minute to warm up and cool down. In the warm-up phase, the image is either dim or completely dark. DLP is getting cheaper as flat panels get bigger and reduce price. Currently, RPTVs still the best technology to deliver huge image with great value.

Plasma television
With prices starting about $700 for the least expensive models, a coveted plasma TV is within reach of most shoppers. But now that you can get a 42-inch LCD for a similar chunk of change, plasma TVs have to depend on factors other than price to remain competitive. One area where plasma still reigns, however, is in very large screen sizes. Today’s 50-inch plasmas – the plasma TV sweet spot – are still less expensive than similarly sized LCDs, and in even larger screen sizes the gap widens considerably. That said, big-screen plasmas are still a solid chunk of change more than rear-projection sets. The pros of plasma TV is thickness of around 3 inches, with very good home-theater image quality, wide viewing angle and superior motion resolution. However, for green concern buyers, they might complaint it less energy-efficient than LCD TV. Plasma TV also slight potential for burn-in, and sometimes lower resolution than similarly sized LCD TV.

Flat-panel TV In Living Room

LCD television
LCDs will generally have a higher resolution than plasmas of the same size. Larger LCDs, as big as 65 inches, remain more expensive than plasma and rear-projection models. In the popular 40 to 42 inch size range, LCD prices have dropped. As of fall 2008, flat-panel LCDs in this size range can be had for as little as $750, just a bit more than plasmas. The upside of LCD TV is available in a range of sizes, and matte screens generally reflect less light. LCD TV theoretically immune to burn-in. Low-end LCD TVs’ image quality generally not as good as on plasma models, and relatively narrow viewing angle compare to plasma TV.

Direct-view television
This is the television a majority of people have. Direct-view or tube TVs can be found in sizes up to 36 inches (diagonal), and as their screen sizes increase, so do their heft and depth. The largest models in the mid-30-inch range can weigh nearly 200 pounds and measure two feet deep. Because of size and weight issues, it doesn’t pay for companies to make larger tube TVs; they simply aren’t practical. Upside is relatively inexpensive. Downside is bulky and heavy; limited screen size; lower resolution; usually incapable of displaying HDTV sources, and rarely PC-compatible (but you still can use S-Video to display your computer image on it, provided your video-card has S-Video output port). Tube TVs are becoming uncommon in stores, but this technology still has a few years left before it dies completely.

HDTV resolutions
Resolution, or picture detail, is the main reason why HDTV look so good. The standard-definition programming most of us watch today has at most 480 visible lines of detail, whereas HDTV has as many as 1,080. HDTV looks sharper and clearer than regular TV by a wide margin, especially on big-screen televisions. It actually comes in two different resolutions, called 1080i and 720p. One is not necessarily better than the other; 1080i has more lines and pixels, but 720p delivers a smoother image that stays sharper during motion. Another format is also becoming better known: 1080p, which combines the superior resolution of 1080i with the progressive-scan smoothness of 720p. True 1080p content is scarce outside of Blu-ray, HD-DVD and the latest video games and none of the major networks has announced 1080p broadcasts.

How important is resolution?
Not as important as you might think. Once you get to high-definition, most people are satisfied with the sharpness of the picture. All other things being equal, HDTV looks more or less spectacular on just about any high-def television regardless of its size or the HDTV signal’s resolution itself.