Why the size limit on LCD tvs?

March 29, 2004 2:29 PM

This one has been bugging me for a while. Why can I spend around $300 and easily find LCD computer monitors that can handle 1280x1024 resolution, but even if you spend thousands upon thousands on a LCD Television, you can only get 1280x768 max resolution? The 768 vertical pixel limit seems to make 1080i HDTV impossible on these new TVs, only allowing 720 and 480. Why the discrepancy?
posted by mathowie to computers & internet (6 comments total)

Well, HDTV is all 16:9 widescreen, right? Therefore, 720p would require 1280x720 (just within the capabilities of the TV you linked), but 1080i would require 1920x1080 pixels, which is well beyond the capabilites of most computer monitors.
posted by kickingtheground at 3:23 PM on March 29, 2004

Looking around Froogle, there are 21" and bigger computer monitors that can go beyond 1600x1200. This one from IBM can do more than 2000x1500, so I'm thinking the technology to have 1080i LCD panels is here, but why aren't any sold that can do it?
posted by mathowie at 3:52 PM on March 29, 2004

As the resolution and size of a TFT LCD goes up, the yield goes down. Therefore cranking both the size and resolution up massively increases the price of any given TFT. Big, they can do. High res, they can do. Big and high res, well, that's a lot of dud displays and wastage for each manufacturing run. Obviously, margins -- already pretty thin for consumer electronics -- will be better on lower-resolution displays.

This Marshall 22" LCD seems to be about all you can do for 1080i on a TFT, and alas, that ain't a big TV.
posted by majick at 4:13 PM on March 29, 2004

I think up till now it's been mainly a matter of production capacity. Sharp is coming out with a 45 inch 1920x1080 display; it will upconvert everything to 1080p. Expect a retail price in the "new car" range.

The thing is, even if you have 1080 vertical pixels, you will still have to perform scaling on non-1080i material. All HDTVs use processors to scale a variety of incoming signals (480i or 480p, 720p, 1080i) to the display's resolution, and the scalers do a pretty good job: scaling really isn't much of a problem.

Lower pixel resolutions aren't much of a problem, either, at normal viewing distances, where the eye can't really tell the difference. HDTV generally, and higher pixel resolutions specifically, allow you to move closer than normal to the screen, where the spaces between low-res pixels start to become visible, creating a kind of "screen door effect". The higher the resolution, the closer you can move. These things vary from person to person, but for the a 37 inch, 1366x768 TV I have to move to within about three feet to see the effect, but who wants to be closer than that? And anyway, at that range the LCD's real problem -- motion processing -- seriously degrades the image.
posted by coelecanth at 10:07 PM on March 29, 2004

That doesn't explain why there's such a price discrepancy between LCD monitors and LCD televisions. For a similar sized screen, a monitor is about £200 and a television is over £500. Why is that?
posted by salmacis at 2:06 AM on March 30, 2004

Electronics could be part of it. The scaler/deinterlacer will add to the cost, as will any motion processor they use to ameliorate the slow pixel response time. You'll have a lot more control over the picture's brightness, tint, etc than you would with a normal LCD monitor. Also, there's a big price difference between units that actually have an HDTV tuner in them, as opposed those that are "HDTV ready".
posted by coelecanth at 6:19 AM on March 30, 2004