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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  • Gazz - Friday, June 19, 2009 - link

    I am useing a samsung 2493HM and have no problems at all with the monitor plays games fantastic although I have the speakers disconected Too small for what I am useing
    BUT it is hard to find one anymore so I checked out the Samsung site and found a range of monitors T220R,T240R,T260R with out speakers but it does not say what pannels they use
    Reply
  • JarredWalton - Saturday, June 20, 2009 - link

    The http://www.anandtech.com/displays/showdoc.aspx?i=3...">2493HM is a TN panel, so you really can't get any "worse" in terms of panel type. There are better and worse TN panels, of course, and the 2493HM was actually good as far as TN goes. Like other TN, it also doesn't have any perceptible lag, which is another plus. If you're happy with the 2493HM, you should be okay with most other displays, provided they do well in other areas. Reply
  • fredsnotdead - Friday, June 19, 2009 - link

    "... an apparently single-minded focus on reducing costs and pricing ..."

    Unfortunately, that seems to be all we Americans are interested in.
    Reply
  • Geraldo8022 - Friday, June 19, 2009 - link

    I am someone who lives "off the grid". I get my power from solar and while I now have quite a number of panels and batteries I still want low power consumption. I wish more manufacturers would be more truthful about how much power their monitors use. I would like to see the websites who test monitors test the power consumption in variety of ways and consistently.
    I read a lot of gripes about monitors. It is surprising to me that there are not websites devoted exclusively to monitors.
    Reply
  • darklight0tr - Friday, June 19, 2009 - link

    You mean like this one?

    http://tftcentral.co.uk/">http://tftcentral.co.uk/

    Its a pretty good site.
    Reply
  • Geraldo8022 - Friday, June 19, 2009 - link

    Yes, I have followed that site, darklight. I think it is very good. It is the only one I know of.
    Jarred, thanks for that info. All I have to go on are things like the specifications at the 'Egg. Good to know.
    I realize power consumption can only be so low and most are interested in other aspects. I am interested in those things, too, Just weigh things differently.
    Reply
  • JarredWalton - Friday, June 19, 2009 - link

    I usually test power draw, Geraldo, but neglected to do that with this LCD. Usually, the max power draw they list (<95W) is at least 50% higher than it what I've measured. I'd expect this LCD to consume more like ~60W at full brightness, or 50-55W with the brightness calibrated to around 200 nits. Reply
  • Mumrik - Friday, June 19, 2009 - link

    "The reference Monitor is an HP LP3065, which we have found to be one of the best LCDs we currently possess in terms of not having display lag. (The lack of a built-in scaler probably has something to do with this.) While we know some of you would like us to compare performance to a CRT, that's not something we have around our offices anymore."



    Buy one then!
    Reply
  • JarredWalton - Friday, June 19, 2009 - link

    Sorry, but no. It serves no point other than to add a large, heavy item to my already crowded office. I'm not comparing with CRTs because 99% of people aren't using or buying CRTs. Either a display has less lag than the LP3065 or it has more lag; it is merely a reference point. If you want to read about how LCDs compare to CRTs, plenty of sites have attempted to cover that topic. Reply
  • james jwb - Thursday, June 18, 2009 - link

    At least one high profile site that can actually make a difference is paying this issue some attention, and i have to thank you for that!

    I particularly like the last part of the article which looks to the future, as in my opinion we still haven't hit a quality stage that truly knocks on CRT's door. Sure, in term of viewing angles, colour, brightness, etc, it's all there, and you can't deny the benefits of LCD's (foot print, etc). But 60hz is just plain poor and i honestly cannot wait for it to fade off the planet. 120hz is vastly superior.

    One last thing. It's possible most of these TN film users who just "don't care" about the sacrificial quality never came from a background of using high quality CRT's. It's very difficult, even today, to move from a 21" professional CRT to ANY LCD and not feel you've compromised in some areas, namely the smooth and snappy response these things have. I have a feeling 120hz will bridge the gap far enough that it'll be very hard to notice any downsides to LCD technology over CRT's. But for a 24" LCD to have 120hz, its going to need display port (or at least, not DVI), and with hardly any graphics cards supporting this yet, what TFT maker would introduce one? They are certainly coming, but right now, as you rightly say, the tech is there, ready and waiting, but the market isn't.
    Reply

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