Most people are familiar with the fact that liquid-crystal LCD displays have different resolutions and sizes, can have a matte or glossy surface and features such as a refresh rate of 120 Hz and 3D support. The range of monitors and variations in specifications can be quite complex and, moreover, the numbers are not always worth trusting. One of the fundamentally most important aspects of liquid crystal displays that determine their operation and what tasks they will best perform is the type of panel. Although there are many varieties of them, all modern screens usually fall into one of three categories, each of which differs from the other in its characteristics.
The principle of operation of the liquid crystal display
The screen consists of two layers of polarized material with an LCD layer between them. When power is supplied to this layer in a liquid crystal display, an electric current causes the crystals to align so that light can (or cannot) pass through them. Having overcome the front polarized panel, the light meets a filter in its path, which passes only its red, green or blue component. A cluster of these three colors forms a pixel on the screen. Thanks to selective lighting, you can create a wide range of shades.
The device of liquid crystal and plasma displays is fundamentally different. In the latter case, instead of the backlight and a set of filters, the image is created by ionized gas (plasma), which is ignited when an electric current passes through it.
TN displays
For several years, monitors with TN panels have been the most common on the market. Manufacturers are always trying in their specifications to report the use of an "alternative" type of liquid crystal display. If it is not specified, then it is most likely TN. The general characteristics of this technology include a relatively low cost of production and a relatively high level of responsiveness. Pixels quickly change their state, which allows for greater smoothness of moving images. Some Twisted Nematic displays have a double refresh rate (120 Hz instead of 60 Hz), which allows them to use “active 3D shutter” technology and display 2 times more information, providing a smoother gameplay. In the latest models, the frequency of image regeneration has increased to 144 Hz, but it is designed exclusively for 2D, and not for 3D.
TN Panel Issues
Although the situation has improved over the years, image quality is often considered a relative weakness of TN technology. A good monitor of this type can provide a clear and vivid image with a respectable contrast, usually equal to 1000: 1 with the "dynamic contrast" mode off.
The main disadvantage of this type of liquid crystal display technology is its relatively limited viewing angles. The most common values are 170 ° horizontally and 160 ° vertically, which is only slightly lower than other panel technologies. Indeed, there is a noticeable color change and even “inversion” when looking at the screen from the side, above or below.
Since these panels are generally relatively large (up to 28 ”), relatively limited viewing angles actually affect performance, even if you sit strictly directly in front of the display. In this case, viewing angles from the center of the screen to the peripheral areas will increase. You may notice that the same hue is presented slightly differently depending on its position on the panel - it is noticeably darker at the top and lighter at the bottom. Because of this, color accuracy and saturation suffer, making this type of display a poor choice for jobs requiring high color accuracy, such as design and photography. An example is the ASUS PG278Q monitor, which is quite typical in what can be seen on the screen from the usual position at the table.
VA panels
When the liquid crystal display attempts to display black, the filters are shaded so that as little light as possible comes from the backlight. Most LCD monitors work quite well, but the filter is not perfect, so the black depth may not be as deep as necessary. A definite strength of VA panels is their effectiveness in blocking backlight when not needed. This gives deeper blacks and higher contrast ratios, from 2000: 1 to 5000: 1 with the “dynamic contrast” mode turned off. This is several times higher than other liquid crystal technologies. VA-panels are also less prone to light leakage or “blurred” at the edges, so they are great for moviegoers, and they are nice to use when performing general purpose work.
Image quality
Another key advantage of VA-type LCDs is their improved viewing angles and color reproduction compared to TN. The color shift on the screen is less pronounced, while the shades can be obtained with greater accuracy. In this regard, they are the best candidates for work critical to color quality, but they are not as strong in this area as IPS or PLS technology. When comparing a hue in the center of the screen with the same tone with the edge or bottom at a normal viewing angle, saturation is usually weakened. In addition, the gamma shift is noticeable, which is most manifested in gray tones, but can also occur for other colors. In this case, the shade seems lighter or darker even with a slight head movement.
Disadvantages of VA Displays
Traditionally, gamma shift is not the main disadvantage of VA panels, as they are usually quite affordable and are offered in a good assortment by companies such as Philips, BenQ, Iiyama and Samsung. A real disadvantage of this type of liquid crystal display device is the relatively low reaction rate. Pixels move from one state to another relatively slowly, which leads to a more pronounced blur during fast motion. In some serious cases, things may seem so blurry that they leave a smoke-like mark (such as the BenQ EW2430).
Varieties of VA technology
Modern types of VA panels used on PC monitors include MVA (multi-domain vertical alignment), AMVA (enhanced MVA) or AMVA + (AMVA with slightly wider viewing angles). AMVA (+) panel models typically use an efficient pixel overdrive, so they do not suffer from extensive smoke-like traces. They are on a par with modern IPS models in terms of the speed of some pixel transitions. Other transitions, usually from light to dark colors, are still relatively slow. An example is the Samsung S34E790C, which when it comes to responsiveness, usually works better than its IPS counterpart, the Dell U3415W.
LCD maker AU Optronics (AUO) has created a 35-inch UltraWide VA panel with a refresh rate of 144 Hz. It is used in devices such as the BenQ XR3501 and Acer Z35. Despite such a high value of the image regeneration rate, some pixel transitions still remain noticeably sluggish. Both AUO and Samsung also produce other VA panels with a refresh rate of the LCD display in excess of 100 Hz. Sharp has several specialized MVA matrices used on several models (including the FG2421) that support 120 Hz. However, doubling the regeneration frequency will be accompanied by an improvement in image quality, if the pixels provide such an opportunity. To help overcome these limitations, monitors with a Sharp matrix use strobe lighting in combination with twice the frame rate, called Turbo240, which pretty much obscures pixel behavior during transitions and reduces eye-catching motion blur.
IPS, PLS and AHVA Panels
When it comes to the end result, these technologies are essentially very similar. Their key difference is that IPS was developed mainly by LG Display, PLS - Samsung and AHVA - AUO. Sometimes they are simply called IPS-type panels. The real marketing advantage is their excellent color accuracy, stability and wide viewing angles compared to other liquid crystal technologies. Each hue is displayed exactly regardless of its position on the screen.
IPS displays differ from TN and VA in that the crystal molecules in them move in parallel, and not perpendicular to the panel. This reduces the amount of light leaking through the matrix, providing better monitor performance.
Enhanced IPS Technology
Some of the more expensive IPS and PLS models go even further, offering support for advanced color gamut, thereby increasing the potential range of reproducible colors and color depth, increasing image accuracy. This makes IPS and PLS panels good candidates for performing graphics-critical tasks. In addition, large IPS monitors have a higher resolution than most of their TN and VA counterparts, despite the fact that today a wide range of resolutions is available for all types of panels. The choice of the number of pixels, the constantly decreasing price and excellent color rendering really expand the attractiveness of this type of display far beyond the boundaries of graphic applications, including games and just working on the desktop.
Responsiveness
Manufacturers such as Dell, LG, AOC and ASUS offer a good range of affordable IPS monitors. This means that photographers, designers or regular budget users can take advantage of this technology. Many modern IPS and PLS monitors are also much more responsive than their VA counterparts and even compete with TN screens, although this is usually the biggest disadvantage of IPS panels. Due to these impressive improvements, some modern models are in demand among gamers who can enjoy more colorful colors that are not spoiled by the effect of unsightly trailing.
IPS Panel Update Frequency
In some modern models of this type, the reaction time of a pixel has actually reached a level at which movements are blurred no more than on any monitor with a refresh rate of 60 Hz. The responsiveness of the display for 120 Hz is not entirely optimal, although the optimal performance is in no way related to the speed of image regeneration. Nevertheless, manufacturers have made sufficient progress in this area, which allowed AUO and LG to launch IPS-type panels with refresh rates of more than 144 Hz.
IPS contrast
Another traditionally weak side of this type of panel is the contrast. Significant shifts are also noticeable here, and IPS-type displays on this indicator are equal to their competitors made using TN-technology. The contrast ratio of them reaches a value of 1000: 1 (without dynamic contrast). However, some users notice one unpleasant problem with the device of this type of liquid crystal displays - the luster or "glow" of dark content caused by the behavior of light in these panels. This usually becomes most apparent when viewing from a wide angle (for example, the Samsung S27A850D). Also, the glow, as a rule, is present in the corners of models with a diagonal of more than 21.5 ", if you sit directly in front of the screen at a short distance.
Thus, IPS monitors are the best color LCD displays, pleasing bright colors, but you should always look not only at the numbers.
Conclusion
Modern LCD monitors use 3 main panel categories: TN, VA, and IPS. Currently, TN technology is the most popular, offering decent image quality and high responsiveness at an affordable price. VA sacrifices responsiveness and, as a rule, is the slowest type of panel, but provides excellent contrast and improved color reproduction compared to TN technology. IPS, PLS and AHVA lead the way in image quality, offering the most consistent and accurate colors while providing excellent viewing angles, respectable responsiveness and reasonable contrast. The user can weigh the advantages and disadvantages of monitors by comparing them, and understanding the general characteristics of liquid crystal displays is an excellent starting point.