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Main => Main Forum => Topic started by: ChadTower on September 11, 2009, 12:33:49 pm

Title: LED monitors
Post by: ChadTower on September 11, 2009, 12:33:49 pm

Has anyone seen these (http://promotions.newegg.com/LG/090809/index.html?cm_sp=Subcat_LCDMonitors-_-LG090809-_-http%3a%2f%2fpromotions.newegg.com%2fLG%2f090809%2f478x88.jpg) in person yet? 

Title: Re: LED monitors
Post by: Beretta on September 11, 2009, 12:49:30 pm

those are actually only "backlit" by led, they're still lcd.

ya led back lit screens usually are more evenly lighted but not always.  :dunno

Title: Re: LED monitors
Post by: ChadTower on September 11, 2009, 01:05:34 pm

Heh, I was wondering why the "new ones" weren't $1500.   ;D

Title: Re: LED monitors
Post by: Blanka on September 11, 2009, 02:30:12 pm

LED backlight is more ECO-fancy talk, than very usefull. They use white LED's made of blue leds with yellow phosphors 99% of the time. They are mostly space-savers, not energysavers or image improvers. And defenitely not suitable for very nice colour gamuts. CCFL is still the best backlight for mainstream LCD's. They are available in AdobeRGB/NTSC gamut, high brightness and even lit. Top of the line LED, the 1500$ stuff, is using RGB backlight LED's. These RGB LED's have even wider gamuts, but they need special calibration tools, as they age not as even as CCFL. Hence the high price of these RGB backlit screens.

Title: Re: LED monitors
Post by: whammoed on September 11, 2009, 03:54:33 pm

Are you talking about LCDs backlit with LEDs or Organic LED?
http://en.wikipedia.org/wiki/Organic_light-emitting_diode

Title: Re: LED monitors
Post by: RayB on September 11, 2009, 03:58:05 pm

Blanka, why not useful? Do you know the advantage of LED backlighting or not?  LCD tvs usually backlight use one or two very bright lights. THat's why blacks are not black. There's always light bleeding through.  Now, if you have individual LED backlighting, they can design a set to TURN OFF LED backlighting (or actually, I would assume vary the intensity according to the picture). The result is no light behind blacks = black blacks.

Title: Re: LED monitors
Post by: u_rebelscum on September 11, 2009, 05:23:31 pm

Blanka is pretty much right.  The Samsung "LED" LCD tvs (http://www.samsung.com/us/consumer/tv-video/televisions/led-tv/index.idx?pagetype=subtype) advertised a lot right now are LED side lit to get the extra thin profiles.  IOW, the LEDs are placed in strips along the sides of the screen.  The placement of the LEDs make it so they are not able to do localized dimming of the LEDs.

So, the Samsung LED LCD tvs do not get the local dimming, don't get the power saving you'd think LEDs have over CCFL, and have the LED color limits.  The biggest thing about them is how thin they are, and they use the name "LED tvs" without any of the cool thinkgs about LEDs.


I do hope OLEDs come out in volume soon.

Title: Re: LED monitors
Post by: Xiaou2 on September 11, 2009, 08:36:18 pm

 If you are industrious, you can change a burnt out tube on an LCD.   
The LCD screen itself doesnt seems to wear.

 However, with OLEDs,  they have a limited lifespan.  Once thats expired,
its complete replacement time.

Title: Re: LED monitors
Post by: Blanka on September 12, 2009, 04:47:14 am

And local dimming is of limited use too. It works for movies, but that's about it. Imagine Pac-man. With local dimming it would dim like 20x20 pixels at a time. The dot's Pac eats get dimmer too!
If you turn the whole screen down to have a black black, the result would be pretty close to local dimming. S-PVA gives pretty decent black and enormous gamuts with regular CCFL techniques. Hard to beat with LED at this moment. Worst aspect of local dimming is that photo-accuracy is completely gone, as there is no way to measure the exact spread of each backlight-led and compensate every affected pixel for that. All LED things today are intermediate steps to single emitting pixels (either leds or feds), without the OLED lifespan.

Title: Re: LED monitors
Post by: BobA on September 12, 2009, 11:21:32 am

Good explaination of the advantages of the expensive LED TVs (LCD with variable LED backlight)

Link (http://reviews.digitaltrends.com/guide/302/led-behind-the-lcd-understanding-led-backlit-hdtvs)

Title: Re: LED monitors
Post by: RayB on September 13, 2009, 01:58:45 pm

Thanks BobA. Works exactly as I thought.

Title: Re: LED monitors
Post by: u_rebelscum on September 13, 2009, 11:53:35 pm

Quote from: RayB on September 13, 2009, 01:58:45 pm

Thanks BobA. Works exactly as I thought.

Yup good link.  Even includes a warning about sidelit vs backlit, too:

Keep in mind that not all LED TVs can achieve this effect. Many of the super-thin LED televisions you'll find use edge lighting to reduce their side profiles, making them slimmer and more efficient, but unable to "turn off" different parts of the screen intelligently the same way a full-array set can. Always make a point of discerning between edge-lit and full-array backlighting, and go with full-array, unless a thin profile is your number one priority.
 (underline by me)

Samsung (http://gizmodo.com/5320720/samsung-led-lcd-un46b7000-hdtv-lightning-review-avoid) and Sony (http://www.gizmodo.com.au/2009/09/sony-xbr10-flagship-lcd-hdtv-has-sidelit-led-wireless-hdmi/) have sidelit LED TVs, and samsung is the one brand I've seen heavily advertising their "LED TVs".

So buyers be aware.