TV Display

DLP, LCD, HDTV, EDTV What do they all mean?

Basically there are two things to know when youre looking for a new TV and delving into the huge array of display technologies. There is the TV display technology itself and the standard it presents.

The NTSC and ATSC are groups that set an explicit technical standard to what can be called a standard television (NTSC) or digital television (ATSC). Standards protect us from fraudulent claims that such n such is an HDTV when really its just a slab of glass.

In the past, a TV and the broadcasts that powered them had to meet the standards of the NTSC before a communication could be called television. That prevented Uncle Bobs set out in Kalamazoo from being a completely different format that didnt work in Hoboken.

Technological advances have made television today exciting but a bit confusing with the array of digital TV display formats. The ATSC defines the formats that get to be called digital television (DTV). The definition encompasses, but is not limited to HDTV. The standardization guarantees that the set you buy at Joes TV Farm is going to work the same way as the one your friend buys at Ricks Boob Tube Emporium.

A Brief Look at the Technical Standards

480i is the standard for TV displays that weve been watching since Roman times: that is, four hundred and eighty visible lines of resolution. Thats what your old-fashioned TV used when you watched Knight Rider. The little i stands for interlaced. This means that every other line of vertical resolution alternates between an on and off position, being visible then invisible at a rate of 60Hz or 60 blinks per second. Since it happens so fast, you cant see the lines disappearing and reappearing before your eyes.

As strange as it sounds, the term vertical lines of resolution actually refers to the lines that lay horizontally. This is a source of constant confusion and even a lot of techie geeks get it wrong.

480P (also called EDTV or Enhanced Definition TV) is the first step in the new Digital TV (DTV) standards. It means all 480 lines of resolution are progressive (thats what the P stands for). Progressive lines of resolution mean all of them are visible at the same time, they never alternate or go dark like they would if interlaced. This is what progressive scan does on a DVD player, something a VCR could never do.

If you have a TV capable of displaying it you can use component video outputs or digital video outputs on a DVD player to see the DVDs video in this progressive scan format. But thats the best your DVD player can do. Sadly, even if you have an HDTV, your DVDs are only showing up in 480P. Dont believe the hype about upscaling DVD players that claim to upgrade your video to HDTV, its mostly marketing hoopla. Your TV already has a scaler and has been upsampling your DVD players 480P all along, you just didnt get the memo.

720P is a DTV (Digital Television) standard that is an actual HDTV resolution. Its seven hundred and twenty progressive lines of resolution. Dont forget the progressive means you can see all 720 lines at the same time with no interlacing. Generally the resolution referred to here is 1280 x 720, which means 1280 lines across in a widescreen format and 720 horizontal lines stacked on top of each other to make the vertical resolution. So again we meet that confusing situation where the 720 in 720P refers to the TVs vertical resolution when really these are horizontal lines.

1080i is another HDTV (DTV) resolution. Its the way CRT (picture tube) based TV sets do HDTV, whereas 720P is how fixed pixel (non-CRT) TVs do HDTV. The reason is that interlacing is just part of the way scan lines work, even though there are plenty of CRT monitors capable of fixed pixel resolutions. 1080i is the equivalent of 720P: the same throughput of raw data is required to produce an image in 1080i or 720P. Any talk of 1080i being better or higher res than 720P is just talk; conversely, any talk of 720P being better is just more empty words.

1080P is the next frontier in video and truly an unexplored frontier. Here we get into refresh rates. All the TV display formats weve talked about refreshed at a rate of 60Hz (actually 59.97Hz, but whos counting), the video standard since the beginning. Therein lies the problem with 1080P: the ATSC has no standard for 1080P/60. That means its an undeveloped frontier. One problem with 1080P/60 so far has been that your TV display is capable of it but no connection standard (like HDMI) has a bandwidth capable of sending that much data to the TV. In effect, anything you watch is going to be reduced to something that is less than 1080P.


TV Display Types

With that brief look at the standards that apply to TV display technologies, we can now look at the display technologies themselves. What follows is a short description of some of the display technologies youll find described throughout HomeTheaterFocus.

DLP is Digital Light Processing, a neat trick dreamed up by Texas Instruments, inventors of the portable calculator and the IC chip.

LCD is one were all probably familiar with, Liquid Crystal Digital. Anyone with a digital watch uses an LCD.

Of course Plasma is the big one that everyone says they want because its the most expensive. Its very nice, but still not perfect.

Lastly there is LCoS or Liquid Crystal on Silicone. Its similar to LCD but every manufacturer seems to have its own variation on it. Sony calls it Qualia and JVC calls it D-Ila, but its all basically the same. It seems nobody likes to call it LCoS anymore, perhaps because of Intels failed LCoS pursuit, who knows.

Now youre an expert on TV Display! Thank you and drive through for your certificate.