How do TFT screens compare to LEDs

TFT monitor / LCD monitor purchase advice - you should pay attention to this

Rotatable LCD monitor (Photo: Samsung / T-Online)TFT monitors are not only slim and stylish, but also distortion-free, low in radiation and use less power than their almost forgotten tube predecessors. But liquid crystal technology has not yet been perfected. There are big differences in image quality, some of which are due to the principle.

TFT monitor: panel type TN, MAV or IPS?

TN, MVA, PVA, IPS, S-IPS - behind these abbreviations there are ultimately three different display technologies that essentially determine the properties of a monitor. Most LCDs will TN displays installed. VA panels in the manufacturer-specific variants MVA, PVA and S-PVA are more likely to be used on more expensive screens, as are the relatively rare ones IPS panels. All panel types have clear advantages and disadvantages. Anyone who knows the panel type of a screen can already estimate whether the monitor will meet their requirements. But unfortunately you can rarely find information about it in the advertising brochures of the electronics stores. Rather, it advertises with response times, brightness and contrast values. What this is all about, which panel type is the right one for which purposes and what else you should pay attention to when buying an LCD - you will find out all of this in this guide.

TFT monitor: LCD, TFT and LED - what is it?

Is there actually a difference between LCD and TFT? LCD stands for Liquid crystal display and is a generic term for liquid crystal screens - from the wristwatch to the big screen. TFT means Thin film transistor and denotes a specific LCD technology. Nowadays all LCD monitors and LCD televisions use TFT technology. That means: whether LCD or TFT - the difference does not matter when buying a monitor. The case is somewhat different with LEDs. Newer LCD monitors are often referred to as LED monitors because they use light-emitting diodes (LED) for backlighting. This saves electricity and enables thinner displays. In the not too distant future, the terms LCD monitor and LED monitor will be practically synonymous, as LED technology for lighting is becoming more and more popular. But there are still many LCD monitors with conventional fluorescent tube backlights (CCFL) on the market.

LCD / TFT monitor: the correct screen resolution

The higher the resolution, the more content and details can be displayed. However, characters and symbols appear smaller with increasing resolution for the same area. Windows does provide functions, these to the higher resolution adapt, but at least with Windows XP and its predecessors, this only works incompletely. In general, LCDs should always be in the specified, the so-called native resolution operate. The image on LCD displays is made up of a fixed number of dots. This is the native resolution. Nevertheless, LCDs can also display lower resolutions. This makes sense, for example, with games that sometimes run more smoothly in a lower graphic resolution. In such a case, either a black border remains, or - the now common effect - the smaller image is stretched across the entire surface and sometimes distorted. The result of this interpolation is a format-filling, but more or less blurred picture and therefore nothing for continuous operation.

The size in inches and cm

In the case of LCD / TFT monitors, the size of the screen diagonal is used, i.e. the distance between the opposite lower and upper corners. The international standard is the specification in inches, one inch corresponds to approximately 2.54 cm. In Germany, however, the centimeter value must also be specified in sales brochures. In any case, an inch to cm conversion table is helpful.

Usual sizes

The smallest and cheapest LCD / TFT monitors have a screen diagonal of 17 inches, which is around 43.2 cm. While 17- and 19-inch monitors were considered the standard a few years ago, screen diagonals between 22 and 24 inches have now become established in the home sector thanks to lower prices. Even 26- and even 27-inch monitors are now affordable - at least with a TN panel. However, a large screen also has its disadvantages. On the one hand, the power consumption increases, on the other hand, quality defects such as uneven brightness distribution (illumination) and a narrow viewing angle are more noticeable on large areas than on small ones.

Resolution and page format for TFT monitors

17-inch monitors usually display 1280 columns and 1024 rows, this standard is also known as SXGA and corresponds to the page format 5: 4. 19-inch LCD monitors usually offer the same native resolution, but on a slightly larger area so that the writing is a little easier to read. LCD monitors in 5: 4 format are, however, on the decline, they are mainly still used in offices. In the home sector, widescreen monitors are becoming more and more popular. Widescreen monitors show the picture in 16: 9, older ones in 16:10 format. They are also called Widescreens designated. The resolution 1920 x 1080, also known as Full HD, known from televisions, has established itself for widescreens from 22 inches. 1680x1050 and 1440x900 are also common.

Viewing angle, brightness and contrast

Vertical viewing angle (installation: T-Online) With all LCD monitors, the contrast when you look at the picture from an oblique perspective. Above a certain angle, practically nothing can be seen. Inexpensive monitors achieve a viewing area of ​​150 to 170 degrees, good monitors of 170 and more degrees. The bigger a monitor, the more important one is generous viewing angle. In the worst case, the corners appear dull, poor in contrast and falsified in terms of colors, despite the frontal seating position. The H value indicates the side viewing angle, the V value the vertical angle. How big the viewing angle is mainly depends on the type of panel used. Monitors with VA (Vertical Alignment)-Display or IPS (In-Plane Switching)-Displays achieve the best values. The cheap and widely used TN- (Twisted Nematic)-Displays show weaknesses here, especially in the vertical angle. TN displays can be easily recognized in the specialist market by the fact that they show color falsifications when viewed from below. In recent years, however, TN technology has caught up, so that many monitors also provide a good picture with a TN display.

Important: the contrast ratio (Montage: T-Online)

TFT monitor: contrast ratio

This is an important criterion for image quality Contrast ratio. It describes the difference in brightness between the brightest and the darkest displayable pixel. If the monitor can display a white pixel e.g. 1000 times brighter than a black one, we speak of a contrast ratio of 1000: 1. Here, too, you cannot put manufacturer information on the gold scales, but generally speaking: the higher the better. In the bargain area, 800 to 1000: 1 is now the standard. There is almost always a TN display in such screens. VA screens usually achieve a higher contrast ratio. For image editing they are first choice.

brightness

Brightness - less important (Graphic: T-Online) The brightness of a TFT display is expressed in the unit of measurement Candela per square meter (cd / m²) specified. In contrast to the often weak notebook and netbook displays, TFT monitors for the desk easily provide 200 candelas and more. That is bright enough for practically all lighting conditions. On the contrary: a display that is too bright can quickly tire the eyes. Therefore, make sure that you can turn down the brightness sufficiently.

Response time - often just window dressing

Streaking if the editorial time is too long (photo montage: T-Online) The response or switching time of an LCD, given in milliseconds, is often emphasized in advertising - wrongly. Earlier LC screens often reacted uncomfortably sluggishly to image changes, but now the editorial time is only of interest to fans of fast-paced action games and films. If the reaction time is too long, ugly streaks will appear on fast-moving objects and the image will appear blurred. A reaction time that is as short as possible is therefore desirable for action games and films. It shouldn't be more than about 10 ms.

Pivot / portrait function, height adjustment, stand

Pivot function (Photo: Eizo) In most cases, too little attention is paid to the mechanics of a screen. The devices differ enormously here. Make sure that the height of the LCD monitor can be adjusted, tilted and, if possible, swiveled sideways. A Height adjustment is the least that can be expected. Take a close look at the processing. Power of Stand also a solid impression? If not, the device threatens to tip over from the table. Cheap devices in particular are often designed to be too "light-footed" and lack useful options for adapting to the seated position of the viewer. On some models, the display is on one Swivel arm attached. Raising and lowering then means that the distance to the viewer changes at the same time. Only more expensive LCD monitors offer something called one Pivot function, also Portrait mode called. It allows the user to tilt the LC display by up to 90 degrees. A software ensures that the image content is automatically adjusted accordingly. This is particularly useful when editing texts or long tables.

DVI and HDMI connection

VGA and DVI connector (picture: manufacturer) A TFT monitor always works digitally internally, so it should always offer a digital connection for the graphics card (DVI, in the picture below). Are common DVI-I (integrated) connectorsthat loop through the analog signal as well as the digital. Another form of digital connection is HDMI. This flat plug connection is primarily used in home entertainment devices such as LCD televisions and Blu-Ray players, but has also established itself in the PC sector. In contrast to DVD, HDMI supports a copy protection mechanism such as that used on Blu-ray video discs (HDCP). You need an HDMI socket if you want to play Blu-ray films on this screen. A monitor that only has an analog VGA (D-SUB) input (Picture above), you should leave it as a slow seller.

Conclusion

  • Take the time to choose the right monitor because you will be dealing with virtually all of the time you spend in front of your PC.
  • Investing in a higher-quality model is almost always worthwhile, also because you are sometimes rewarded with long warranty periods.
  • Do not rely on the manufacturer's information on contrast, viewing angle and response time, but study the device with your own eyes if possible.