interesting features of LCD screens
Main conclusions of a quick search for bying an LCD monitor at about 500 Euros (VAT included, 2005-02).
» Uses and interests
- best clarity for text
- decent colours and graphics
- tolerable performance in movies
- very limited interest in games
Most information has been gathered from the sources mentioned at the end.
» the occasion
I bought a cheap 19-inch LCD with a TN-Film panel and without DVI, which I returned within two days. I could not work for more than a few minutes without getting a headache. ClearType was not clear, colours were uneven, and response was slow even for text. Before deciding on a replacement, I looked at tests and analyses to see what would be the best LCD choice for people who work mainly with text. This report summarizes two of the most interesting things I learned.
For the record, I finally bought the NEC 1970NX. Its colours are not perfect, and its white is a bit glaring, while black text on gray backround has a certain hardness, but at least I can work with this LCD for ten hours or more without perceived eye fatigue. ClearType is fairly clear, but not as clear as, e.g., on some Vaio displays I have seen. Here is the system it is connected to.
digital video input (DVI)
Modern (2005-02) graphics cards have both analog and digital outputs. LCD screens work with digital signal, but not all have a digital video input. Some have only an analog input and they convert the signal by means of an analog-to-digital convertor (ADC). The signal produced by a graphics card is digital. So, if the card has DVO and the LCD has DVI, they can be connected digital-to-digital. Some say that it does not make a great difference whether the dispaly has DVI or not, and sometimes it is said that the quality of the rendering is not affected considerably by the double conversion. Others say that rendering is significantly clearer when the digital signal is fed directly to the display.
An LCD with DVI is about 50 Euros dearer than an equivalent model without DVI. I could not afford trying and returning LCDs for too long, so I did not buy again an LCD without DVI.
the panels
Panel manufacturers are about five (5) worldwide and supply all known LCD brands. The panels that come out of each production line are divided to three categories according to quality (one relevant factor is the number of dead pixels). There are several types of panels, and not all are same. Panel type seems to be the most important factor for the quality of an LCD screen, followed by the type of video input, digital or analog. The main types of panels are three:
» TN+Film
The cheapest and quickest, used for basic consumer displays at 17″ and 19″. An indication that the panel is TN+Film are the milliseconds: the lower this value, the higher the probability that the panel is TN+Film. TN+Film panels produce 262.000 colours, and display 16.2 million colours (not 16.7) by means of dithering. The Wikipedia article (see Sources) says that dithering is visible by 10—15% of people, and a part of this percentage cannot use such a display for a very long time.
- Ideal for gamers, thanks to very fast response time
- Limited viewing angle (nominally it can be more than 150/150; however, an angle a few degrees off the axis can have a very felt result on the brightness, as well as on the uniformity of colours)
- Not uniform colour rendering
- Not ideal for films and design
- Average quailty of colours and black
In general, TN+Film panels are not recommended for professional use. Some models:
- A great favourite among Greek gamers is the 19″ LG 1915S. It does not have DVI.
- A top-quality model of is the 17″ Eizo L550.
» MVA (Multi Vertical Alignment)
Slightly more expensive than TN+Film designs. One major manufacturer is Fujitsu.
- Usually they go up to 16.7 million colours without dithering, but they are not very bright
- Very good for office use and good for movies
- Wider viewing angles
- Good colours and good black
- Not very good for action games; low response time results in shadowing
» PVA (Patterned Vertical Alignment)
Improved version of the MVA design. Manufactured by Samsung.
- A top-quality but relatively expensive model is the 17″ Eizo L557
» IPS (In-Plane Switching)
The most expensive technology for now (2005-02). They are used in models of 19″ and up by LG, Philips and other brands.
- Natural 16.7 million colours
- The widest viewing angle, comparable to CRTs
- The best clarity and sharpness of text; very good for office use and presentations
- Good brightness, very good contrast and colour quality
- Good for movies
- Not optimal rendering of black
- Not even backlight (discernible in darkness)
- Not good for action games, but better than the MVA/PVA design
- Sensitive; they should not be touched, according to the Wikipedia article (how are they supposed to be cleaned?)
» S-IPS (Super IPS)
Improved version of IPS, with faster refreshing of pixels. This seemed to me to be the best solution in total. Some are said to be good even for action games. Among the relatively economical models of the S-IPS type, I read good reviews for the following:
- NEC 1970NX: Successor of the much-praised 1960ΝΧ
- Philips 190B5: The cheapest of this type in Greece
- LG 1920B: Another one with the same panel
- Iiyama E481S: Another one with the same panel
sources
- http://en.wikipedia.org/wiki/TFT_LCD: At Wikipedia
- http://www.xbitlabs.com/articles/other/display/lcd-guide_27.html: Short conclusion of extensive article at Xbit Laboratories
- http://forum.ixbt.com/post.cgi?id=print:28:15144: Extensive list with the panels used in most modern LCDs, at a Russian forum
- http://www.insomnia.gr: Many good threads in this forum (in Greek)
- http://www.thelab.gr: Another good Greek source
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