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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  • erple2 - Wednesday, June 17, 2009 - link

    I bought the hp 2475w to replace my old Dell 2001FP model. I don't have any complaints about it. The color is better than the Dell was. I wound up using both monitors, however, as I have the space on my desktop for both of those monitors. It's nice to have the side monitor (relegating the 2001FP to side monitor ... heh heh) for "other tasks" while focusing on the main monitor. Plus, they're about the same vertical size.

    Again, I haven't noticed any real complaints with the 2475w beyond what I'd also complain about the 2001FP. In fact, the brightness appears better and more uniform.
    Reply
  • Mastakilla - Wednesday, June 17, 2009 - link

    Are you crazy?

    I (and I hope smarter people allow me to say "we") do NOT want high color gamut, because there is simply no support for it...

    until it is supported on OS level, 99% of the applications that 99% of the people use simply look like crap :(

    stop supporting this wide gamut bullshit please!!

    I want to see what I'm supposed to see and not some over saturated crap

    and even if you are a graphics artist using correct wide gamut hardware / software: what is the point in it? 99% of the people will see the image wrong anyway...
    Reply
  • haplo602 - Wednesday, June 17, 2009 - link

    graphic artists prepare photos for PRINT not web viewing :-)

    also a proper wide gamut monitor has an sRGB mode where the colors match (or should match) sRGB, no oversaturated colors.
    Reply
  • bigboxes - Wednesday, June 17, 2009 - link

    The OP is misinformed. A wide color gamut is very important for color accuracy. Maybe not for the casual user, but definitely to the content creator. Reply
  • The0ne - Thursday, June 18, 2009 - link

    Hence that's why I think most of the users commenting here aren't really in the business to even use, appreciate or know what they're getting. It's all about having the best but now knowing what to do with it. That's just my opinion of course.

    Now before anyone starts getting upset, I am still in the printing business dealing with credit cards and checks. I can tell you from numerous research and seminars that most people really don't care, don't know or don't appreciate what some of these technologies provide. And rightly so because it's a niche market.
    Reply
  • 10e - Wednesday, June 17, 2009 - link

    You said "In the case of the FP241VW, color accuracy and color gamut are lower than average, but that a better backlight could address that shortcoming."

    I'd agree the factory accuracy of the FP241VW is not good, but the fact that it was always a standard gamut display is/was an advantage. We get caught up in numbers and forget that in regards to gamut, for 99% of the users out there sRGB gamut is more than good enough, and is preferable to the over saturated reds and greens of wide gamut panels, which is something that so far even Windows 7 has not been able to properly address.
    Reply
  • 10e - Wednesday, June 17, 2009 - link

    In my experience the Samsung S-PVA panels used in these monitors lag: Dell 2408WFP, 2709W, Samsung 245T, 275T Plus. There is noticeable input lag where the mouse cursor plays "catch up" with what the mouse hand is doing. I had an FP241VW and it never displayed this characteristic in DVI or VGA. It goes to show that some people will notice it, and others won't. Reply
  • darklight0tr - Wednesday, June 17, 2009 - link

    I understand, but it is getting tiring to constantly get beaten over the head with that info, as is done in this article.

    I think PVA gets a bad rap, and I think the lag has more to do with the image scalers than it does with the panel technology itself. Just look at the reviews for the S-IPS 3008WFP. There are the same complaints from a few users about input lag on that display, and one of the main changes from the 3007WFP was the addition of an image scaler. All of the PVA displays you mention have scalers as well.

    That said, despite all of the hype you read on the Internet over lag, there are probably tons of very happy PVA users (including myself) playing games on their PVA displays, oblivious to any lag.
    Reply
  • jabber - Thursday, June 18, 2009 - link

    Indeed I have two Samsung 214T 21" 4:3 PVA panels and they are super sharp and I see no ghosting or 'catch up' whatsoever.

    Running through COD4/BF2/EVE etc. etc.

    As stated above I dont think its the panels. I reckon its the case of more expensive panel so often the manufacturer will cut corners on the other electronics inside to make it hit a price point.

    PVA's are fine. However, as with any monitor purchase, if you are serious about screen quality...do your homework!
    Reply
  • jabber - Wednesday, June 17, 2009 - link

    Been using PVA screens pretty exclusively for gaming for around 3 years now. Havent noticed or seen any performance/screen lag issues in all that time.

    Maybe you are thinking back to the turn of the century screens?

    Certainly isnt an issue in my opinion.
    Reply

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