Let's Talk Panel Technologies

We've already given a brief rundown of TN panels and what they offer, but let's expand that to include the other three panel technologies. Here's the breakdown:

LCD Panel Technology Comparison
Panel Type IPS MVA PVA TN
Viewing Angles Excellent Excellent Excellent Okay Horizontal; Poor Vertical
Color Quality Usually Excellent Good to Very Good Usually Excellent Usually Good
Contrast Ratio >500:1 >500:1 >500:1 Usually >500:1
Color Gamut Depends on Backlight Depends on Backlight Depends on Backlight Depends on Backlight
Processing Lag 0ms (Usually?) 0-3ms 17-50ms 0-2ms
Response Time 6ms GTG 6ms GTG 6ms GTG Typically 2ms GTG
Cost Very High Very High? High to Very High Low to Medium

There are many similarities between IPS, MVA, and PVA - and note that these are now usually "Super" IPS/PVA or "Advanced" MVA. There are a few variants within the base panel type (i.e. E-IPS, H-IPS, and S-IPS), but the patterns generally remain true. Even TN panels have several areas that often overlap with the other techs. Let's look at the various areas in detail.

Starting with contrast ratios and color gamuts, modern LCDs have now reached the point where all panels will generally achieve a greater than 500:1 contrast ratio. Do not confuse this with "dynamic" contrast ratios, where the backlight can vary in intensity to help produce darker blacks and brighter whites at the cost of color accuracy - and it's also impossible to have bright whites and dark blacks concurrently, unless you have zoned backlighting, as current panels run the backlight at a uniform level for the entire display. Backlights also affect color gamut, with the key aspect being how much of the standard color spectrum the backlighting creates. Anything over 100% of Adobe RGB 1998 is overkill, and for most users even 82% of Adobe RGB 1998 (100% NTSC) is sufficient.

The other areas show more differentiation. Viewing angles greatly favor anything other than TN. It's worth noting that while vertical viewing angles often aren't as important as horizontal angles, if you want a display that can run in portrait mode you will definitely want to avoid TN panels (since in portrait mode the poor vertical viewing angles become horizontal angles). Manufacturers are also very generous in how they determine viewing angles, as they only require the display to maintain a 10:1 contrast ratio to qualify as "viewable". Realistically, we would say TN panels have a vertical viewing range of about 30° (15° up/down) before you notice severe image quality changes (i.e. from above the display becomes washed out, and from below it becomes very dark). Horizontal viewing angles on TN panels are probably closer to 60°, or even 90° if you're not super demanding. Compare that to the claimed 160° vertical/170° horizontal and you'll realize how inflated this spec has become with the target 10:1 contrast ration. In contrast, IPS/MVA/PVA all manage a fairly consistent 120° viewing angle in both vertical and horizontal alignments - possibly more if you don't mind the trapezoidal distortion caused by viewing from oblique angles. These displays advertise 176 or 178° viewing angles.

Color quality is also generally better on everything that's not TN, although here the (only) MVA panel we've tested seems to fall a bit short. When combined with viewing angles and the distortion that can cause to colors on TN panels, we'd stick with one of the other technologies if you want to get accurate color. In truth, this is mostly important for imaging professionals, as your eyes and brain will compensate to the point where you usually won't notice the difference. TN panels can also perform well in color accuracy, but they frequently do not because the manufacturers don't feel that's the target market - and in fact many displays have poor color accuracy by default because a lot of people prefer saturated colors. Also note that TN panels do not natively reproduce 8-bit color spectrums, relying instead on dithering and interpolation (switching rapidly between the two closest gray levels) to expand their 6-bit panels into pseudo-8-bit displays. This often shows up in color accuracy testing on TN displays with one or two colors having a high delta E while the rest are very close to ideal.

Pixel response times are another bloated statistic, with claimed response times of as low as 1ms for some TN panels and most now stating 2ms GTG (gray to gray). In theory, that would mean refresh rates of up to 500 Hz would be possible with no image persistence between frames. While no LCD currently available offers a refresh rate higher than 120Hz - and even those are relatively rare, only recently showing up with NVIDIA's 3D Vision technology - we still see image persistence on every LCD we've tested. That's not to say TN isn't a bit faster, but the difference is small enough that most users won't notice; either the response time will be "slow" on any LCD (relative to a CRT), or else it will be fast enough that you won't care.

Processing lag is potentially related to pixel response time. We don't know for sure if the lag comes after the crystal matrix receives a new voltage or if it comes before the voltage change, but we do know that of the tested panel technologies currently available, PVA seems to suffer the worst in this area by far. We only have one reference point on MVA panels, but we've read other reviews that support the idea that MVA response times are significantly better than on PVA. Processing lag can also come from hardware scalers used to support other resolutions, the prime example being Dell's 3008WFP. Even at native resolution, that display reportedly has anywhere from 10ms to 50ms of processing lag (depending on the revision that was tested). We have not seen any similar issues with other panels, most likely because scalers for lower resolutions have been around for quite a while and have been tweaked for optimal performance.

We also haven't tested any IPS panels outside of 30" LCDs, so we don't know for sure how IPS fares at other resolutions. Given 30" panels command a price premium, they may perform better overall than the smaller IPS displays; however, we believe IPS panels inherently process images as fast as any other LCD technology. Finally, it's worth noting that we have not been able to compare any LCD panel to a CRT for processing lag - we don't have access to any good CRTs anymore for comparison. Anecdotal evidence suggests that the best LCDs may still introduce a 15-30ms lag relative to a CRT. For better or worse, LCDs are here to stay and CRTs are a dying breed, so we'll constrain processing lag comparisons to LCDs and other newer panel technologies (i.e. OLED, SED, plasma, etc.)

Finally, we have to put all of this into perspective by introducing price into the equation. TN panel LCDs are by far the cheapest, often costing half as much as the same size display with an IPS/MVA/PVA panel. Since the non-TN displays do cater more towards professionals, some of the price difference may be artificial, but TN panels are still the least expensive option. They are also the oldest LCD technology, having been around since the dawn of LCDs. As much as you might want a high quality IPS display, when it comes down to a choice between a $400 22" IPS display or a $175 TN display, it's no surprise that a high percentage of people go with the inexpensive TN option.

So which panel technology is "best"? Clearly, it depends on many factors including pricing. Without price, I'd personally take an IPS display over any of the others, but again I may be biased by having only used 30" IPS panels. Many LCD HDTVs also use IPS panels, and given the recent growth in the HDTV market we'd expect there to be a few more improvements in the base technology. Like other displays, however, many HDTVs are now beginning to ship with TN panels, so if you're thinking about getting a new HDTV you'll definitely want to exercise care in what you buy.

Index A Closer Look at the BenQ FP241VW
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  • genegold - Saturday, August 15, 2009 - link

    Jared - Take a look at HP's Business/Performance monitors for four new IPS models and two PVAs.

    While I've never seen a PVA monitor, one thing I've read in serious user discussions is how they are made for photo professionals and not for use with typical web/office/standard applications. For the latter, these monitors' colors are oversaturated and the text mediocre or worse. Users who have bought them for the latter frequently complain and are advised to return them for something more for the consumer market. The common theme is that these monitors are made for use with Adobe Photoshop and to some degree with other color-managed applications (of which Firefox is the only browser).

    I did try a Dell 2209WA E-IPS recently, actually two samples, and found them to be very good monitors for everyday use, with the big exception for my purposes that the model's minimum brightness setting (0%) is equivalent to a bright office. That didn't work well with my moderate day lighting and evening darkness (and aging hazel eyes).
    Reply
  • gking11 - Thursday, August 06, 2009 - link

    I got my FP241VW a couple of months ago after I was lucky enough to find it for sale online, and brand new to boot!

    While I did get a dead pixel (fortunately it was low enough that it didn't hinder my viewing much), the display is the closest thing to perfection in terms of an all-purpose LCD, especially for gaming. With my Pantone Huey, I have it calibrated and, boy, do the colors come out!

    Without further ado, here's the direct link to the site where I bought it from (it's $385 as of this post, I bought it for $400 then): http://www.entercomputers.com/benq-fp241vw-24-wide...">http://www.entercomputers.com/benq-fp24...l?SID=cf...

    *Running away from stampede!*
    Reply
  • rlx - Sunday, July 19, 2009 - link

    Two points often disregarded in reviews.

    I bought a Samsung SM275T and although I am very happy with it, I find the readability of small anti-aliased text to be not as good as I expected. I find the reason to be that each pixel is in fact made of two pixels on that monitor. Both subpixels combine to double the number of different colors the monitor can display. I find that in some cases one subpixel is on while the one below is off.

    This creates a dithering effect and somehow interacts with antia-liased text. The net effect is that I find small text to be harder to read )or I should say recognize). I compared with an analog monitor and with a 720P LCD tv and I am quite sure that using two subpixels the way Samsung does it is not the way to go for a monitor that is intended for general use.

    The other point is that vertical viewing angles are very important to me on a portable computer screen. Since my vision is not that good I sometimes need to move my head closer to the screen and this movement changes the angle of view. This is why I find laptops (TN) very difficult to use. People with normal vision can do everything from a single position and the vertical angle of view might not be as important for them.

    Richard
    Reply
  • rlx - Wednesday, July 22, 2009 - link

    I meant twice the number of gray levels of course (re. twice the number of colors) but why Samsung has done all that work of doubling the number of pixels just to gain one bit in the number of gray levels.

    If both sub-pixels have a slightly different number of levels, say sub-pixel No.1 has four levels of gray 0,1,2,3 and sub-pixel No.2 has 6 0,1,...,5 then the number of achiveable gray levels is 24 out of 31. They are 0, 3/15, 5/15, 6/15, ... up to 2.

    The light coming through sub-pixel No.1 is l1/3 and the light through No.2 is l2/5. The total light through both is (l1*5 + l2*3)/15.

    The 24 achivable levels out of the possible 31 are, (going from 0 to 30): 1001011011111111111111101101001.

    If one scales those numbers up then one sees why Samsung can do much better than double the number of gray levels by using two sub-pixels instead of a single pixel.

    Maybe I learned something from my typo.
    Reply
  • rlx - Tuesday, July 21, 2009 - link

    I just wish to clarify my statement about the readability of small size anti-aliased text on the SM275T. I double checked with my older analog SM950P that I run at 1600x1200. From a distance, the small text is definitely much easier to read on the SM275T.

    I am a bit annoyed by the dithering effect when I take my glasses off so I can get close to the screen. From that short range, small size text looks smooth on the analog screen while artifacts appear on the SM275T.

    However even at this small range the text on the SM275T is still readable while it is not really so on the analog screen.
    Reply
  • - Sunday, July 19, 2009 - link

    Just wanted to say great review, it mirrored my sentiments exactly.

    P-MVAs (A-MVAs perhaps not as much) were incredible displays. Found in $300 24" soyos I was amazed how much better they were than pre-highgamut S-PVAs in every regard(color response and even slightly in gamma shift). When AUO stopped their entire MVA line it was party over for cheap high quality displays, as Samsung thinks alittle too highly of it PVA technology.

    Although I still have an LG 24" with a P-MVA, my other two recent additions were H-IPS HP2475w. Great deals at $600 and worth every penny and then some, but still not bending the price curve down enough. TN has its place, but not in anything over $150 imho.
    Reply
  • Sabresiberian - Thursday, July 09, 2009 - link

    Beats the heck out of any LCD made to date. Yeah they were $2500 when they were made, but that would likely be much less now, especially if it were made for gamers not professionals and priced to sell properly to that market.

    Sorry, I just had to say it; maybe there's a Sony exec that reads Anandtech and will get sparked, lol!
    Reply
  • Mr Bill - Friday, June 26, 2009 - link

    I bought this monitor last fall from BenQ for $400 just before they went out of production. I wish I had bought two. Its a very nice monitor. Reply
  • ocyl - Thursday, June 25, 2009 - link

    Thanks, Jarred, for the efforts that you've put into writing this article. Here is a bit of idea sharing :)

    1. You might be interested to check out NEC's MultiSync P221W (S-PVA, 1000:1 contrast, black level control, GammaComp, sRGB preset, 4-way adjustable stand, 16ms response time; $500) and the newly announced E222W (looks like a PVA given its 178º viewing angle; 1000:1 contrast, sRGB preset, 4-way adjustable stand, 5ms response time; $270). I spent two weeks of time on research when I was in the market for a new TFT-LCD monitor last November. I ended up purchasing a NEC MultiSync LCD1990SX (LTM190E4 PVA, 1500:1 contrast, ColorComp, OmniColor, black level control, sRGB preset, 4-way adjustable stand, 20ms response time; $480) and couldn't have been happier.

    2. As we know, scaling is one of the main contributors to processing delay. While I don't currently own a Radeon and therefore don't know if this can be done in Catalyst, it's possible to relieve monitor from scaling tasks in ForceWare. There are four options available at nVidia Control Panel -> Display -> Change Display (Flat Panel) Scaling: Use nVidia Scaling, Use nVidia Scaling with Fixed Aspect Ratio, Use My Display's Built-in Scaling, and Do Not Scale. I don't have measuring equipment so I can't perform any meaningful investigation, but perhaps it's something that AnandTech may find worthwhile looking into.
    Reply
  • ocyl - Friday, July 17, 2009 - link

    NEC announces MultiSync EA231WMi, a 23" IPS monitor
    http://www.techpowerup.com/99491/NEC_Unveils_Multi...">http://www.techpowerup.com/99491/NEC_Un...t_23_inc...
    Reply

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