Most people are familiar with the fact that Liquid Crystal Displays (LCDs) come in a variety of resolutions and sizes, can be matte or glossy, and features such as 120Hz refresh rate and 3D support. The range of monitors and variations in specs can be quite complex, and what's more, you can't always trust the numbers. One of the fundamentally most important aspects of liquid crystal displays, determining their performance and what tasks they will best perform, is the type of panel. While there are many varieties, all modern screens generally fall into one of three categories, each with different characteristics.
The principle of the liquid crystal display
The screen consists of two layers of polarized material with an LCD layer between them. Whenin a liquid crystal display, power is supplied to this layer, an electrical current causes the crystals to align so that light may (or may not) pass through them. Having overcome the frontal polarized panel, the light encounters 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. With 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 illumination and a set of filters, the image is created by ionized gas (plasma), which lights up when an electric current passes through it.
TN displays
For several years, TN panel monitors have been the most common on the market. Manufacturers always try to communicate the use of an " alternative" type of liquid crystal display in their specifications. If it is not listed, then it is most likely TN. The general characteristics of this technology include a relatively low production cost and a relatively high level of responsiveness. Pixels change state quickly, allowing for smoother moving images. Some Twisted Nematic displays have doubled the refresh rate (120Hz instead of 60Hz), allowing them to use "active 3D shutter" technologies and display 2x more information for a smoother gaming experience. In the latest modelsthe image refresh rate has been increased to 144 Hz, but it is designed exclusively for 2D, not 3D.
TN panel problems
Although things have improved over the years, picture quality is often considered a relative weakness of TN technology. A good monitor of this type is capable of delivering a sharp and bright image with a respectable contrast ratio, typically 1000:1 with "dynamic contrast" turned off.
The main drawback of this type of liquid crystal display technology is the relatively limited viewing angles. The most common values are 170° horizontal and 160° vertical, which are only marginally lower than other panel technologies. Indeed, there is a noticeable color change and even "inversion" when looking at the screen from the side, top or bottom.
Because these panels tend to be relatively large (up to 28”), the relatively limited viewing angles actually affect performance, even when sitting directly in front of the display. In this case, the viewing angles from the center of the screen to the peripheral areas will increase. You can see that the same shade is presented slightly differently depending on its position on the panel - it is noticeably darker at the top and lighter at the bottom. Color fidelity and saturation suffer as a result, making this type of display a poor choice for work that requires high color fidelity, such as design and photography. An example is the ASUS monitorPG278Q, which is fairly typical in what can be seen on screen from a normal table position.
VA panels
When the LCD tries to display black, the filters are shaded so that as little light as possible comes from the backlight. Most LCD monitors do this quite well, but the filter isn't perfect, so the black depth may not be as deep as desired. A definite strength of VA panels is their efficiency at blocking backlight light when it is not needed. This produces deeper blacks and higher contrast ratios, from 2000:1 to 5000:1 with "dynamic contrast" disabled. This is several times higher than other liquid crystal technologies. VA panels are also less prone to light bleed or haze at the edges, making them great for movie buffs and a pleasure to use for general purpose work.
Image quality
Another key benefit of VA LCDs is the improved viewing angles and color reproduction compared to TN. Color shift across the screen is less pronounced, while tints can be obtained with greater accuracy. In this regard, they are the best candidates for color-critical jobs, but they are not as strong in this area as IPS or PLS technologies. When comparing a hue in the center of the screen with the same hue at the edge or bottom,At a normal viewing angle, there is usually a decrease in saturation. In addition, gamma shift is noticeable, which is most pronounced in gray tones, but can also occur for other colors. In this case, the shade appears lighter or darker even with a slight movement of the head.
Disadvantages of VA displays
Traditionally, gamma shift is not a major drawback of VA panels as they are generally quite affordable and available in a good range from companies such as Philips, BenQ, Iiyama and Samsung. The present disadvantage of this type of liquid crystal display device is the relatively slow reaction speed. Pixels transition from one state to another relatively slowly, resulting in more pronounced blurring during fast motion. In some serious cases, things can appear so blurry that they leave a smoke-like trail (like the BenQ EW2430).
Varieties of VA technology
Modern types of VA panels used on PC monitors include MVA (multi-domain vertical alignment), AMVA (improved MVA), or AMVA+ (AMVA with slightly wider viewing angles). AMVA(+) panel models typically use efficient pixel overdrive so they don't suffer from extensive "smoke-like" trails. They are on 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 examplemight serve as the Samsung S34E790C, which generally performs better than its IPS counterpart, the Dell U3415W, when it comes to responsiveness.
LCD manufacturer AU Optronics (AUO) has created a 35-inch UltraWide VA panel with a 144Hz refresh rate. It is used in devices such as BenQ XR3501 and Acer Z35. Despite this high refresh rate, some pixel transitions are still noticeably sluggish. Both AUO and Samsung make other VA panels with LCD refresh rates in excess of 100Hz. Sharp has several dedicated MVA matrices used on several models (including the FG2421) that support 120Hz. However, doubling the refresh rate will be accompanied by an improvement in image quality if the pixels provide this capability. To help overcome these limitations, Sharp-mounted monitors use strobe backlighting combined with twice the frame rate called Turbo240, which greatly hides pixel behavior during transition 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 by Samsung and AHVA by AUO. Sometimes they are simply called IPS-type panels. The real marketing advantage is their superiorcolor accuracy, stability and wide viewing angles compared to other liquid crystal technologies. Each shade is displayed accurately regardless of its position on the screen.
IPS displays differ from TN and VA in that their crystal molecules move parallel to the panel, not perpendicular to it. This reduces the amount of light seeping through the sensor, resulting in better monitor performance.
Advanced IPS technology
Some of the more expensive IPS and PLS models go even further by offering support for extended color gamuts, thereby increasing the potential range of hue reproduction and color depth, improving image fidelity. This makes IPS and PLS panels good candidates for graphics-critical tasks. In addition, large IPS monitors offer higher resolutions than most of their TN and VA counterparts, despite the wide range of resolutions available today for all panel types. The choice of pixel count, ever-decreasing price, and excellent color reproduction really extend the appeal of this type of display far beyond graphics applications, including gaming and just desktop work.
Responsiveness
Manufacturers such as Dell, LG, AOC and ASUS offer a good range of affordable IPS monitors. This means that photographers, designers, or everyday users on a budget can take advantage of this technology. Many modern IPS and PLS monitorsare also much more responsive than their VA counterparts and even rival TN screens, although this is usually the biggest disadvantage of IPS panels. Because of these impressive improvements, some current models are finding favor with gamers who can enjoy more colorful colors without being spoiled by the unsightly trailing effect.
IPS panel refresh rate
In some modern models of this type, the pixel response time has actually reached a level where motion is no more blurred than on any monitor with a refresh rate of 60 Hz. Display responsiveness for 120Hz is not exactly optimal, although optimal performance has nothing to do with image refresh rate. Nevertheless, manufacturers have made enough progress in this area, which allowed AUO and LG to release IPS-type panels with refresh rates above 144 Hz.
IPS display contrast
Another traditional weakness of this type of panel is contrast. Significant progress is also noticeable here, and IPS-type displays in this indicator have caught up with their competitors made using TN technology. Their contrast ratio reaches a value of 1000: 1 (without dynamic contrast). However, some users have noticed one annoying problem with this type of liquid crystal display design - the glare or "glow" of dark content caused by the behavior of light in these panels. This usually becomes most obvious when viewed from a wide angle (for example,Samsung S27A850D). Also, glow tends to be present in the corners of models larger than 21.5" when sitting directly in front of the screen at a short distance.
Thus, IPS monitors are the best color LCDs with vibrant colors, but it's always worth looking at more than just the numbers.
Conclusion
Modern LCD monitors use 3 main categories of panels: 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 is generally the slowest panel type, but provides excellent contrast and improved color reproduction over TN technologies. IPS, PLS and AHVA lead the way in image quality, offering the most consistent and accurate colors while delivering 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 LCDs is a great starting point.
