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
POST A COMMENT

114 Comments

View All Comments

  • james jwb - Thursday, June 18, 2009 - link

    PS, also want to say that trying to get S-IPS/PVA in notebooks is also a great service to us out there who dream of this day, again, thanks for trying to highlight this issue :) Reply
  • JarredWalton - Thursday, June 18, 2009 - link

    Dual-link DVI can do 120Hz at 1920x1200 - it's twice the bandwidth of single-link DVI. Most modern GPUs also support dual-link, but right now to my knowledge only 30" LCDs require it. Reply
  • james jwb - Friday, June 19, 2009 - link

    ah that's good to know, and now you've said it, pretty obvious! Reply
  • stubey - Thursday, June 18, 2009 - link

    I have the Benq FP241w, the older version of this model (without the lag-reduction technology). It is still widely available for around £350. Well worth it.

    It has 1:1 pixel-mapping, brilliant viewing angles, colour, adjustable / rotating stand etc.

    Another example of older monitor better than the majority of newer more expensive ones.

    The HP LP2475w is meant to be brilliant also - although probably more like £450......

    Reply
  • marraco - Wednesday, June 17, 2009 - link

    THANKS A LOT
    for reviewing the real lag, instead of the "pixel response time".

    Is the reason for I keep my CRT monitor instead of upgrading to a LCD. I really would like to update to a LCD, but never found a LCD without "phantoms". Vendors lie, lie, and lie about 5 ms response time, but when you see the images, they are really crappy.

    This is somewhat hidden by the blur effect on some games, but I hate the blur effect, and ever disable it.

    Most LCD monitors on exhibition shows only static or slow motion images, and I know why: they can't show fast framerates without ghosts.

    I cannot buy a monitor until I see it working, but most retail vendors do not show the monitor working with fast moving images, so I absolutely crave for benchmark articles reviewing it.

    I even written to nvidia.com forum asking for driver support. Drivers should include a calibration tool for remediation of this lagging ghosts. A possible enhancement would be to display the new framerate substracting a dimmed quantity of the former frame, so ghosts gets somewhat hidden, but got no answer from nvidia. Maybe they have really high quality monitors, and don't understand the need for it, so please, if you are reading this article, go to nvidia/ATI, forums/support, and ask for it.

    Thanks a lot. I hope this kind of reviews generalize on internet, so LCD really improve.
    Reply
  • marraco - Wednesday, June 17, 2009 - link

    http://forums.nvidia.com/index.php?showtopic=99591">http://forums.nvidia.com/index.php?showtopic=99591 Reply
  • marraco - Wednesday, June 17, 2009 - link

    here is a link to the nvidia forum where you can ask for this driver feature:
    Reply
  • marraco - Thursday, June 18, 2009 - link

    This is the link for ATI/AMD:
    http://forums.amd.com/forum/messageview.cfm?catid=...">http://forums.amd.com/forum/messageview...=347&...
    Reply
  • marraco - Tuesday, June 23, 2009 - link

    I got an answer from ATI:

    http://forums.amd.com/game/messageview.cfm?catid=2...">http://forums.amd.com/game/messageview....279&...

    It looks like such feature is implemented at least for video.
    Reply
  • Hrel - Wednesday, June 17, 2009 - link

    My biggest concerns with monitors are Viewing angles first, then response times, (I don't care if it's processing or pixel lag or input lag I shouldn't EVER see ANY ghosting or be seeing 1 or 2 frames behind what my computer is processing and outputting), then contrast ratios and brightness and last is color accuracy. I'm completely satisfied with my current 20" Sceptre's color accuracy. It's a HELL of a lot better than my Dell Studio Laptop, that thing is so far off it's "almost" funny; but not really cause it's also kinda pissing me off. I AM NOT satisfied with the viewing angles, I use cardboard to prop up the back of it to angle down so the image isn't mucked up when I watch tv on it; it has tilt, it just doesn't tilt far enough. Reply

Log in

Don't have an account? Sign up now