Screen Tearing: LCD vs LED


My friend had previously bought both LCD and LCD LED backlite TVs. He claims to have noticed screen tearing on the LED backlite TV. He has also seen screen tearing on LED backlite monitors as well, but says he has never seen screen tearing on a standard LCD monitor/TV playing the same games. Due to his experience he thinks there might be an issue with LEDs over standard LCDs.

As I understand things, LED monitors/TVs are identical to LCDs except in the methods they use to light the screen. Therefore I would assume both LCD and LED backlites would be indentical in performance (this is under the conditions they have the same refresh rates and response times, being displayed by the same PCs/consoles). 

After stating the above, my question is is there any difference in performance (aside from colour and contrast) between standard LCD and LCD LED backlite monitors/TVs? Has anyone ever heard of LED monitors/TVs having this issue whereas LCDs did not?



Well, LED only refers to the backlight, and an LED backlight should make colours pop out more, while reducing power consumption. That means LED is a "standard" LCD, but only with an LED backlight instead.

I think there are either a pletheroa of variables not accounted for when your friend made the claim, such as refresh rates, brand craftsmanship, and other specs, or, your friend doesn't know what screen tearing is. IMHO, I think it's both. Screen tearing is when two seperate frames are drawn simultaneously before the monitor can refesh the picture. It really only happens when framerate is above refresh rate, and V-sync corrects that. Screen tearing has NOTHING to do with the backlight, which is the only difference between LCD and LED (LCD).

Wrong on all accounts. An LCD screen uses a very fine matrix of uniform crystals whose orientation is controlled through the application of current. The way that they color the light is by the use of a series of really tiny color filters that are overlaid on the matrix of crystals so that they pass light through the appropriate filter when they are angled to allow light to pass through. Now this is simply the display, the backlight doesn't have anything to do with how it refreshes itself, as the backlight is only there to give the crystals light to refract in the first place. Sony has actually gotten really ingenious with their multi-zoned LED backlighting where they can actually dim or completely turn off the LED backlighting for a section of the screen that it detects has gone dark in the video input. So you can get some pretty crazy blacks with that method, since usually there is something called light bleed where the light slips through the spaces between the crystals and makes the whole image look under-saturated. Now older or less expensive LCD panels will eschew the newer, fancier, and far more power and heat efficient backlighting technique in favor of good old Cold Cathodes, which produce a nice white light, but often cause excessive light bleeding around the area that they are places, because the filters that are placed behind the display aren't adequate to fully disperse and collimate the light (make all the light waves travel in a single direction.) Anyway, the only major difference that you would even begin to notice between these two backlighting solutions is the stock frequency of the pulses of light, and it is really unimportant unless it is significantly out of phase with the refresh rate of the monitor, in which case it still wouldn't appear as taring, but instead as a frame or two of darkness, or maybe a stutter in the video.

Now, LED displays function a bit more like a Plasma display, where each pixel is actually composed of a matrix of two red LED's and a blue and a green LED. Since the combination of all of these equates to white light, and the part that colorizes the light also produces it, and modulates the apparentl output of light, then it is unnecessary to have a backlight. OLED panels function similarly, but can have much smaller pixel sizes and much purer colors while producing less heat. The interesting part about LED's though is that they can function at very high rates of speed, even up to 240 Hz, so you wouldn't experience taring so long as you made sure that the monitor was in sync with the video source. This is why VSync is really useful, because it forces the video card to wait to update the frame until the beginning of a refresh cycle. On 60 Hz monitors this can cause a noticeable lag, on 240, not so much.

However, most of the problems with taring are not because the graphics solution not being able to provide the source with a fast enough fill rate, but that this rate fluctuates in ways that the monitor's refresh rate does not. So you might notice that half of the screen was drawn in on one refresh cycle, then lost on the next when the other half was drawn in. Typically, the faster the refresh rate, the lower the need for Vsync to be on, but you can get similar effects to Vsyn if your game or graphics card tweaking software has a "set fps goal" or a "cap at xx fps" Setting that to any value of the refresh rate divided by an even number will result in lower chances of taring. If you can actually push the game, consistently, with over 60 FPS, then you should set it to cap at 60 FPS and you will very likely not see any taring because the graphics card automatically tries to push the frames to compensate for the monitor's refresh rate. Because all the self-flagellation of FPS scores showing up on FRAPS or whatever when you are on a 60 Hz monitor is not impressive. Get a 120 Hz monitor and show that you are able to push 120 FPS consistantly and then we'll talk.

Thank you for the replies.

@Mndless When you speak about LED displays you are not talking about LCD screens with LED backlighting, but a display made from LEDs? In that case it is the screen/display that provides both the colour for each pixel AND it's own light. Is there any way of identifying a LED display monitor/TV in comparision to a LCD monitor/TV with LED backlights? And what advantages would an LED display have over a LCD display?

Besides that, if I understand correctly the lighting does not affect screen tearing. Screen tearing is caused by the FPS being out of sync with the refresh rate, in which case using v-sync and/or putting a limit on your GPU FPS to match your refresh rate will fix or at least minimize screen tearing. Therefore the monitor/TV "type" doesn't come into play when you are trying to solve screen tearing. 

Please correct me if I am wrong.

Yup, you got it. As far as LED monitors go, they aren't actually that useful for computers because manufacturers have a bit of difficulty shrinking the standard LED's down small enough to give you the rather paltry pixel density of having 1080p on a 23" monitor. I'm not sure exactly what their problem is, but I imagine it was why in 2007 everybody got so excited about the introduction of OLED displays. And sony was every gamer's secret wetdream when they premiered that one 11" monitor for $2500. Nobody could understand why you would want one, until you looked into the deep dark abyss that were the blacks. Anyway. OLED (mostly AMOLED) displays would be worth having for the significant increase in price, but aside from that option, an IPS display is an excellent option simply because it has amazing viewing angles (think 178 degrees) and really consistant color reproduction. How that differs from your standard LCD display is pretty vague but seems to have quite a lot to do with the size of the plane in which the liquid crystals are held and the mechanism for which they are rotated (being two electrodes that pass a current through the little well that the liquid crystals are held in in their matrix) creating an electric field that follows parallel with the plane of the well rather than simply radiating outward. Anyway, vagueness over, if you have money for a monitor, and you don't act like a douchebag who thinks he can tell the difference between a 2 ms and a 5 ms response time, then buy an IPS display. They are pretty.

you never stated the hertz of the lcd tv and the led backlit tv.. on 60hz tvs lcds you'll see tearing for sure.. i returned 6 different tvs before i settled on a 240hz tv for one of many reasons. it was very noticable on 2d scrolling games like worms armageddon. ;p

I never stated the refresh rate because I am not wondering what affect it has on screen tearing. I was curious if the actually lighting of the monitor/TV made a difference, which I have found so far does not affect screen tearing.