Micro Mart Forum / Digital Photography & Video / Technical Forums / LED, LCD monitors. / Latest Posts

RE: LED, LCD monitors.

Teafie — Tue, 08 Jul 2008 22:23:58 GMT

Cheers slippy, I will look into the ratio jobie.

The monitor will be for games, I dout it will ever see a DVD.

http://www.practical-home-theater-guide.com/contrast-ratio.html

Got it.

RE: LED, LCD monitors.

Slipstreem — Tue, 08 Jul 2008 20:21:39 GMT

Whatever you buy Teafs, just make sure that you can disable or at least adjust the dynamic contrast gizmo. If it drives you half as nuts as it does me then you'll regret it if you can't. It's going to be noticeable on displays claiming contrast ratios from 2,000:1 upwards to some extent. Most of the ones claiming a 'perfect' 10,000:1 are fairly obvious about it. :)

Cheers, Slipstreem. :cool:

RE: LED, LCD monitors.

Teafie — Tue, 08 Jul 2008 20:15:05 GMT

Speds :)

looks like your links answerd my question.

Thanks.

Boy do you guys know your screens.

Im after a new monitor 22"

24" is just to big and will not acheive what I want.

I guess I will just go for something 2/5 ms and 5/10,000 contrast ratio.

Oh, I also here that a big price drop will filter through on current tft's as of now. So prices should be down sept/oct time I would of thought.:)

RE: LED, LCD monitors.

Spedley — Tue, 08 Jul 2008 20:06:49 GMT

I was going from memory of this story. 11", not 17" :blush:
[url]http://www.engadget.com/2007/04/12/sony-1-000-000-1-oled-tv-on-sale-in-2007/[/url]

RE: LED, LCD monitors.

Bruce R — Tue, 08 Jul 2008 19:17:50 GMT

@Spedley :)
The you-tube video that you found was of typical small-scale production OLED displays, where those shown are probably the only ones made so far. £100 for a 17" display sounds like a 'what the market will bear' for initial production releases. The BARCO NX-4 is a far more expensive approach, in a different league and using existing bright LED technology, embedded in dark silicon resin tiles that can be used in large stage and outdoor displays, where you can mount many tiles in modules and many modules. A more high tech alternative to multiple CRT 'video walls'. Bill Gates could [u]easily[/u] afford one for a living room wall ! :D

RE: LED, LCD monitors.

Slipstreem — Tue, 08 Jul 2008 19:02:26 GMT

As with current CCFL back-lit displays, that would have the problem of still needing a colour filter matrix on the front of the display. If you make every single pixel capable of being R, G and B, you have a much higher perceived colour resolution than having to light up groups of R, G and B pixels.

Concentrate the power of a tri-colour LED down a hole 1 pixel square and you have a phenomenal potential in terms of CD/metre squared. They'd need a lot of cooling at that brightness though.

I think that's why the 800x600 res on a DLP projector actually looks surprisingly good. Each display pixel is displaying the entire R, G and B signal, so an entire screen of, say, red is possible rather than only one-third of it with individual primary coloured pixels. :)

Cheers, Slipstreem. :cool:

RE: LED, LCD monitors.

Spedley — Tue, 08 Jul 2008 18:52:05 GMT

Ah, I see the point of LED backlights.

A normal white backlight is made up of all the colours of the rainbow so when the 'red' element of the LCD allows light to pass through it actually allows many shades of red to pass through.
If you backlight is made of LEDs then generally, only 3 specific frequencies are produced (i.e. one for red, one green and one blue). If this is tuned to the optimum light transmition frequency of the LCD then you get a greater contrast and more accurate colour.

RE: LED, LCD monitors.

Bruce R — Tue, 08 Jul 2008 18:48:14 GMT

Hi Teafie :)
Organic LEDs (OLEDs) already have, but only in small panels on small devices. The larger panels are still costly to make, whilst HD production and consumer demand is for ever larger, even more expensive panels. It'll probably cost about twenty billion to set up the first large scale OLED production plant. Given their interest, it'll probably be a South Korean or even a Chinese plant. The large demonstration panels have so far been produced at great cost in small-scale production plants, suffering from yield problems. Give it another five years before LCDs are more widely replaced by OLEDs ? ;)

Edit PS - cheap really large displays will probably be photo-chromic, looking like matt pictures and relying on incident light, but like fusion power, I probably won't be around to see it. :w00t:

RE: LED, LCD monitors.

Slipstreem — Tue, 08 Jul 2008 18:44:56 GMT

Philips are taking a different approach to increasing the contrast ratio by using HCFLs (hot cathode fluorescent displays) which can be switched on and off at sub-microsecond speeds. With careful timing control, the lamps can all be modulated in-sync with the screen being scanned. It's still not as good as individual LEDs, but it's ten times better than what a lot of sets manage now in terms of convincing dynamic contrast enhancement.

Most other LCD TVs still rely very heavily on just modulating the back-light brightness with a response time of tens of milliseconds and they all look very false to me. To those who remember, it's like watching a CRT TV with a badly sagging HT. It basically looks "broken". I specifically chose an LCD TV/monitor [i]without[/i] any form of dynamic contrast enhancement as you can't always fully disable it on the TVs that have it. At least my genuine 1500:1 can reproduce everything between its limits linearly. It just looks so much more natural to my eyes.

Individual pixel control for back-lighting is the only way to actually make it work properly. Anything else is a bluff and a compromise. :)

Cheers, Slipstreem. :cool:

RE: LED, LCD monitors.

Spedley — Tue, 08 Jul 2008 18:44:01 GMT

There are a few backlit LCD's which are much thinner and don't use anywhere near as much power.
I don't think they are the same technology as OLED screens but I think they do use some kind of OLED (presumably to make the blue component of white).
([url=http://www.sony.co.uk/res/attachment/file/45/1193315654445.pdf]Sony Tri-colour (pdf)[/url])

LED screens are another thing entirely and they are still £1000 for 17" at 1/2 full HD
[url=http://www.youtube.com/watch?v=VlzBgogRtDI]Youtube OLED screen[/url]

RE: LED, LCD monitors.

Teafie — Tue, 08 Jul 2008 18:29:24 GMT

well apparently led lcd tfts got invented back in 2005 ish so its been 3 years for them to have easily infultrated the market.

Hmmm?

RE: LED, LCD monitors.

Bruce R — Tue, 08 Jul 2008 18:24:28 GMT

Most back-lights are supplied as part of the panel package supplied by the very few panel makers to the many monitor makers. I hadn't heard of the illuminators going over to 'white' LEDs, although that's now quite possible. What I have heard about is OLED panels, made up of discrete LEDs which, having an 'off' mode can give a truer 'black' impression, plus brighter colours, but commercial results with small OLED panels haven't been too great due to manufacturing limitations. ;)
So, are you actually referring to the as yet few experimental large OLED displays that are around ? :cool:

LED, LCD monitors.

Teafie — Tue, 08 Jul 2008 17:28:48 GMT

There is alot of talk at the mo about LCD monitors, whos back lights are LED's apparently enabling the monitor to produce something like true black.

Ive been browsing through e-tailers and none of them list what kinda back light they use.

Or am I missing something obvious.

Thanks in advance.