Choosing a computer screen is more important than you might think. And for good reason, whether to work, to surf the Web, to play or to watch videos, it is him that we watch all day long. It is therefore better not to be mistaken at the time of purchase, whether to equip a fixed PC – in tower or mini format – or to complete a laptop with an external screen.
First of all, you have to choose a size and a format. In the high-tech universe, the size of a screen is measured by the diagonal of its “useful” part, expressed in inches (1 inch = 2.54 cm). The larger this diagonal, the larger the poster area. The most common sizes currently are 24 and 27 inches, but there are larger ink diagonals. The aspect ratio corresponds to the ratio between the width and the height of the image. The most common is 16:9, like on televisions, which is very comfortable for general use and for watching videos. but there are also 3:2 (squarer) and 21:9 (wider), for example.
Another fundamental criterion is definition. It corresponds to the number of elementary points (the pixels) which form the image and is expressed by a product (number of pixels in width x number of pixels in height). The higher it is, the more “defined” the image. This is important for video, but also for “computer” use, because the more pixels there are, the more elements are visible on the screen. The current standard is Full HD (1920 x 1080 pixels), but many screens offer higher definitions such as 2560 x 1440 pixels or (3840 x 2160 pixels, ultra high definition (UHD) also called 4K. Attention, the definition must be adapted to the size of the screen, because there is no point in having 4K on a small screen (a 14 inch, for example), because the pixels and all the elements displayed are far too small, even with excellent eyes. The size of characters and icons must then be increased, which reduces the space actually usable. In practice, it is considered that Full HD is well suited to 24 inches, that WQHD (2560 x 1440 pixels) is suitable for 27 inches and that you need 32 inches to really enjoy 4K-UHD.
Last criterion easy to check on a screen, the maximum refresh rate which corresponds to the frequency of renewal of the displayed image and is therefore measured in hertz (Hz). The traditional rate is 60 Hz (60 renewals per second), but 75 Hz is establishing itself as the new standard, offering much better visual comfort with an image that is both more stable and smoother. No need to deprive yourself! The very high rates (120 Hz, 144 Hz, etc.) mainly concern gamers, because is contributes to better responsiveness.
Once these questions have been evacuated, the most important criterion on a daily basis is obviously the quality of display. It depends on the on-board electronics, but above all, on the technology used for the panel, the part of the screen that displays the pixels. Several technologies exist on the market, each with advantages and disadvantages. The oldest is the TN, which is quite economical, but which does not offer good viewing angles and suffers from poor contrast: at the slightest difference in position, the image is altered. Avoid, even for simple office work. VA technology gives much better results, including excellent contrast. But it also suffers from reduced viewing angles and generates some streaks on moving images. It is IPS which currently represents the best compromise, thanks to its very wide viewing angles and high quality rendering with very good contrast. Moreover, color fidelity is no longer really a problem today, manufacturers having made real progress in this area. Unless you opt for a very low-end screen at a low price, there are no more unpleasant surprises. The most demanding can always turn to a top-of-the-range model with advanced calibration functions, for photo editing for example. Rendering quality is also judged on the number of shades that can be displayed by the screen, which must cover at least the entire standard color space called sRGB. Professional designers can demand more for brighter, more realistic hues, especially on reds. They then need a wider color space, such as Adobe RGB or DCI-P3, which are also more suitable for HDR (High Dynamic Range) rendering technology.
The other characteristics of the screens are not to be neglected, in particular all that concerns the connectors. If HDMI is now the standard for connecting a computer, other standards exist, such as DisplayPort or Thunderbolt. Generally speaking, the more outlets and formats, the better! Especially since it is perfectly possible to connect several computers to the same screen simultaneously (a desktop and a laptop, for example) and switch the display as needed. In addition, many screens now incorporate USB sockets, which are very practical for connecting peripherals. The presence of speakers is also appreciable, even if their audio quality cannot compete with those of real speakers (but it always helps!).
Finally, ergonomics and comfort should not be neglected either, in particular the possibilities of adjustment in height, in inclination or even in rotation, to switch the display to portrait mode, useful in certain cases. Note also that all current screens are compatible with the Vesa standard (format 100 x 100 mm) which allows them to be hung on a wall. Nice, but hardly useful in practice…