O que é um painel PVA ou TN dos monitores?

Woodz

Power Member
Pretendo adquirir um monitor novo e tava na ideia de um Samsung 226bw ou um 226CW.
A minha questao é que já vi falar aqui no forum imensas vezes de paines TN e etc e nao sei o que isso é.
Alguem pode fazer a delicadeza de me elucidar desta noobice?:003:

Cumprimentos!
 
Tens aqui um excelente resumo (em inglês) sobre os diferentes tipos de paineis, caracteristicas, vantagens/desvantagens, etc:
We effectively have three major classes of TFTs: TN, VA (MVA/PVA), and S-IPS. Each of these main classes has its own subclasses, but the differences tend to be minor. We will first discuss the most primitive TFT technology, twisted nematic (TN).

TN displays are known for their excellent response time, but also poor viewing angle. The vertical viewing angle can be especially limited, making the use of portrait mode (pivot) difficult. Most people sit right in front of their screen without moving, so the problem may be insignificant. TNs tend to produce a less uniform brightness output than other panels, so looking at large areas of a light color can be uncomfortable at any angle. When you look at a TN from below, the image will appear almost fully inverted.

Despite their viewing angle problems, TN panels make great gaming displays. Modern TNs with no speed acceleration technology reach an 18-25 ms response time, the time it takes for one crystal to transition from one color to another color (all transitions take a slightly different amount of time, especially when different color pairs are involved). LCDs with slow response time exhibit effects of ghosting, a double image lagging behind the main image, in moderate to very fast motion, and stuttering in instances of slow motion. TNs often also have the least input lag, a delay in which the LCD's image is a couple frames behind what's being sent. This is, potentially, a make-it-or-break-it factor that depends on how sensitive you are and whether you can adapt to it, and it will be covered more in-depth in the next section. Please note that all measurements mentioned here of image delay are input lag plus the response time it takes to show a digital timer's number segments on the LCD (described more in-depth under Input Lag section).

Next up are the VA (vertical alignment) panels: MVA (multidomain vertical alignment) and PVA (patterned vertical alignment). In actuality, both have very similar characteristics even though they operate by different means. Typical VAs offer around twice the maximum brightness of the average TN panel. They are also famous for their high dynamic range and low black level. Response time, with RTC (response time compensation, a crystal acceleration technology) is right up there with TN panels that aren't paired with the same tech. Their input lag, partly caused by RTC, tends to be the worst of the three most popular panels. The total image delay (again, mainly input lag) can get up to 70 ms in the worst cases with most large VA-based screens averaging around 30-50 ms. It's usually not as much as an issue for smaller VA panels, although one, the Acer AL2051W, reaches 34 ms on average.

MVA and PVA panels are generally economical (MVA the cheaper of the two), but are still less present on the market than TNs. Their viewing angle is dramatically better, although slightly yellowish tinting is noticeable at certain angles. VA panels with RTC are generally a good choice for just about anything, if you can find one at the size and price you desire. Unfortunately, their input lag could eliminate the choice altogether for you (especially when it comes to big screens).

Sharp has a line of panels named ASV (Advanced Super View), named for its wide viewing angle. This is also a VA technology but currently, at least in the US market, it is only used in TVs. It has been reputed to deliver excellent image quality and response time.

Lastly, S-IPS panels are the choice of the professionals. They boast near-perfect viewing angles, and often offer better color reproduction than VA panels. Response time, with RTC, is right in the ballpark of the VA panels with RTC. This panel type is probably the sweet spot for having good colors and low response, as well as having a medium input lag time. Their image delay tends to be slightly worse than TNs (that average 15 ms or so). In a few cases they can go up to 30 ms but most IPS panels hang in there well enough, not reaching the magnitude of a VA panel.

IPS panels suffer more from SDE (screen door effect), a phenomenon in which your eyes are able to visualize all the individual pixels on the screen. In this way, they can cause more eye strain. This isn't an issue for the majority of users, and may only happen when working with text or other light-background material. Their brightness is typically somewhere between that of TNs and VAs, but variants such as AS-IPS can offer white levels of up to 470 nits and lifelike, vibrant colors. In most cases however, this maximum brightness does not indicate a usable value. Their grayscale reproduction must be sacrificed at somewhere over 300 nits. Unfortunately their availability is extremely limited, and prices are soaring. It is expected that they will soon disappear into a pro-only market carrying a hefty premium with their price tags.

If you'd like more condensed information on the panel types discussed above, check out the Matrix of all Matrices.

We have just gotten through discussing the trends of all the major panel types. Beyond this point, the differences are model-specific.

LCD manufacturers offer two types of glass: anti-glare (sometimes called hard 3H or 4H coating) and glossy. Anti-glare LCDs account for more than 90% of the desktop market. These coatings reduce the glare that you may be used to from old CRTs, but they do it as the cost of dynamic range, clarity, and color vibrance. Glossy coatings increase dynamic range by a good amount but can be frustrating to use if bright lights happen to be shining right at the screen. They exhibit an excessive amount of glare in these conditions, so they should be used in rather dim but consistently lit environments for the best results. Glossy panels tend to crush darker details and exaggerate midtones.

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I. Panel Types
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  • TN
    • Good response time
    • Very good dynamic range (400:1 with older generation, 700 - 1000:1 with newer gen TNs)
    • Poor vertical viewing angle (especially from below)
    • Poor screen uniformity and stability (white can look "dirty"), which can reduce perceived contrast
    • Lateral viewing angle is not great (darker/lighter details can appear and disappear depending on the angle)
    • 8-bit gradient (16.7M colors) through dithering and FRC
    • Lack of true 8-bit DAC causes color tinting, fringing, and burning in gradients and poor reproduction of darker tones
    • Very unlikely to get image persistence
    • Low input lag (lower latency in screen update)
    • Economical, but more prone to backlight bleeding and QC (quality control) problems than other panel types, too

      Target Audience:

      • Gamers, general use (Word/Excel) who don't mind a poorer viewing angle. Less suitable for movies and poor for photo editing.
  • VA
    • Decent response time (varies)
    • Great dynamic range (1000:1 - 1500:1)
    • Horizontal color shift (certain gray tones rapidly shift at just a few degrees, worse than TNs in many cases)
    • Image details absent at perpendicular angle
    • Good vertical viewing angle
    • Good screen uniformity (white is uniform and does not shift at angles, contrast is decent)
    • 8-bit gradient (16.7M colors) through true 8-bit DAC (although dithering is possible with certain models)
    • True 8-bit DAC allows better reproduction of gradients and sometimes better dark tones than TN panels
    • Unlikely to get image persistence
    • High input lag (high latency in screen update)
    • Good value, and the least QC problems of all panels

      Target Audience:

      • Gamers, general use (Word/Excel) who want a more stable viewing angle. OK for photo editing, although beware of color shifting. Not bad for movies, but not always great due to color shift.
  • IPS
    • Decent response time
    • Medium dynamic range (400:1) or higher for AS-IPS/H-IPS/A-TW-IPS (700:1)
    • Minimal color shift at any viewing angle (only slight brightness reduction, and very little gamma/tint shift)
    • Image details present across entire screen
    • Good screen uniformity (white is uniform and does not shift at angles, contrast is amazing)
    • 8-bit gradient (16.7M colors) through true 8-bit DAC (although dithering is possible with certain models)
    • True 8-bit DAC allows better reproduction of gradients and sometimes better dark tones than TN panels
    • More neutral grayscale reproduction and warmer, less harsh image (most like a CRT) than S-PVA panels
    • Medium input lag (low or high depending on model)
    • More susceptible to image persistence
    • Tends to be very expensive although benefits can be visible to normal users
    • Prone to quality control problems: read reviews

      Target Audience:

      • Photo editors will crave this type of panel. IPS-type panels are suitable and generally better for anything else too, including gaming and general use. Some people may prefer an S-PVA for higher dynamic range but an IPS panel, due to its viewing angle characteristics, probably has a higher contrast (ability of the LCD to reliably reproduce tones and nuances).

Quanto aos monitores que referes são ambos com painel TN, que é o mais económico e popular.
 
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