Whats the difference between a plasma tv and a lcd tv? And whats the difference between a lcd tv and a hdtv.?

Answer 1

An HDTV is a TV that receives and displays signals in high resolution. Standard TV's display only about 480 lines of resolution; HDTV's display 720 or 1080 (the latter is "true" HD).

Plasma and LCD are two of the more common technologies used for HDTV's (though they do have "EDTV's", which use the same technology at the lower resolution of 480 lines), and they're what's used for "flat panel" TV sets. Plasma uses millions of little phosphors--think of them as tiny bulbs, each containing a special gas--that light up. LCD uses an array of millions of liquid crystal cells (the same stuff in your cell phone, laptop, or calculator) that are backlit by a light source.

Both technologies have their pros and cons--LCD's don't have as good of a "contrast ratio" (e.g. the blacks aren't as black), and can get expensive at sizes larger than 42". Plasmas are bigger and brighter, but they're prone to "burn-in"--traces of a static image displayed for a long time remain even after the picture is changed--and they lose their brightness over several years.

There are other display technologies used for HDTV's--there are a few CRT (Cathode Ray Tube) models out there which use basically the same electron gun technology as your regular, standard TV, and there are DLP's (Digital Light Projection), which use millions of tiny mirrors that tilt at a rapid rate to project an image on a screen. These differ from Plasmas and LCD's in that they're not thin, flat panels. Other, less popular technologies are LCD projection and LCoS/HD-ILA, used in some Sony and JVC models.