Published on June 13, 2011 3:12 PM

Monitor Tech: PLS vs IPS vs PVA vs OLED: Where Next?

Samsung is about to launch a monitor using a new display technology called plane-to-line switching, or PLS, which is related to IPS.  Could it be the future standard for desktop monitors?

The monitor in question, the S27A850, isn't even on the market yet but the initial test results seem to confirm everything that Samsung has promised for it: this really could be the future of LCD with wide viewing angles and the added benefits of contrast ratios and ghosting levels that can rival the latest IPS displays.

600:1 contrast ratios today, infinity tomorrow?

The biggest hurdle now is the contrast ratio: whether it's below 600:1, as claimed by the first Russian lab to test the S27A850, or closer to 800:1 as we've estimated based on the average discrepancy between their test results and ours, it's not particularly impressive.

But there's an easy solution for Samsung, which need to change the backlighting technology to use Full LED, with hundreds of LEDs isn a grid behind the whole display, rather than Edge LED with just a few dozen around the edges.

The difference between Edge LED backlighting (left) and Full LED backlighting (right)

The switch from one to the other works wonders, and coupled with a dynamic contrast system, which needs to be in place the whole time, the contrast ratios produced can stretch to infinity.

The winning combination of PLS and Full LED backlighting could be the best on the market, meeting public demand for wider viewing angles.  Unfortunately for gamers and those hoping to enjoy 3D, the liquid crystals used with PLS technology still seem to be too slow to satisfy them.

Ghosting on IPS and PLS: why not OLED?

Oleg Aramonov measured a 'response time' of 6.4 ms on the Samsung S27A850, the first PLS monitor.

At DigitalVersus, we measure the 'ghosting time', rather than the 'response time'.  Both measurements time how long it takes, in milliseconds, for the screen to change colour, but they're based on slightly different criteria.

Oleg's version is more theoretical and follows a well-defined industry standard.  Our own test is much more hands-on, and although we're the only ones to use it, we think that ghosting time it's a more realistic representation of the time it takes for a monitor to switch from one frame to the next.

Overall, our test results give a less favourable impression than those on, which we think is more realistic.  You can argue the toss over which approach is better, but it's probably easier to compare some of our results with's:

Monitor (Panel Technology)
Response Time
Ghosting Time
Samsung S27A850 (PLS)
6.4 ms  
Dell U2711H (IPS) 5.7 ms 12.5 ms
Acer GD245HQ (TN 120 Hz) 3.1 ms 5 ms
LG 15EL950 (OLED)   5 ms

With the two examples where we've both tested the same monitor, the Dell U2711H and the Acer GD245HQ, our 'ghosting time' measurements are around twice as long as's 'response time' figures.  This suggests that we should find a ghosting time of 12.5 ms on the new Samsung monitor, which is a lot worse than what the best OLED monitors can offer.

For 3D to work, it's absolutely essential that the ghosting time is under 8 ms.  If it's higher than 12 ms, then crosstalk will creep into scenes, leaving viewers seeing double in 3D and ghosting in 2D.

120 Hz TN displays are super-responsive, but the viewing angles are s8o narrow that on larger screens, different areas of the screen can look different.

The fastest technology currently available is OLED, which brings together wide viewing angles, nice slim screens, and, in most cases, excellent responsiveness, although that isn't always the case, because we have seen some pretty slow OLED monitors as well.

Otherwise, there are also PVA and ASV displays with ghosting times as low as 8 ms, but with narrower viewing angles than IPS displays, and, of course, narrower still than OLED.  Finally, plasma screens rely on an entirely different technology, but they are very bright and some viewers can see the individual pixels jumping when they look at the screen too closely.

OLED Monitors in 2012

LG and Samsung are both planning to launch their first OLED screens next year.

Both manufacturers readily admit that they're set to be expensive, but should be more affordable than Sony's last attempt, which saw a 25'' display costing $6100.  Prices will only come down after a while ...

> Monitor Reviews: 22''-30'' LCD Displays