Lcd monitor

LCD Monitor

When it comes to the various parameters of LCD monitors – this topic is regularly discussed in our articles as well as on every hardware resource that deals with monitors among other things – three levels of discussion can be distinguished.
The basic level is, “Does the manufacturer try to fool us?” This question has a trivial answer. Serious manufacturers of monitors don’t come down to mere lies.
The second level is more complicated, “What do the declared parameters mean, anyway?” This boils down to discussing how the parameters are measured by the manufacturers and what practical constraints on the applicability of the measurement results there exist. For example, the response time parameter was defined in the ISO 13406-2 standard as the total time it takes an LCD matrix to switch from black to white and to black again. Tests prove that for every matrix type this transition takes the least amount of time whereas a transition between two tones of gray may take much longer and the matrix won’t look as fast as its specs suggest. This example doesn’t belong with the first level of discussion because the manufacturer can’t be said to lie to us: if you select the highest contrast setting and measure the “black-white-black” transition, it will coincide with the specified response time.
But there is an even more interesting level of discussion. It’s about how our eyes perceive this or that parameter. Putting monitors aside for a while (to return to them below), I can give you an example from the acoustics field. From a purely technical point of view, vacuum-tube amplifiers have rather mediocre parameters (like a high level of harmonics, poor pulse characteristics, etc), so they don’t reproduce sound accurately. However, many listeners are fond of the sound of tube-based equipment. Not because it is objectively better than that of transistor-based equipment (as I’ve just said, it is not true), but because the distortions it brings about are agreeable to the ear.
Of course, the peculiarities of perception only come into view when the parameters of discussed devices are good enough for such peculiarities to matter. You can take $10 multimedia speakers and they won’t sound any better whatever amplifier you connect them to just because their own distortions are grosser than the flaws of any amplifier. The same goes for PC monitors. When the matrix response time amounted to dozens of milliseconds, there was no point in discussing how the human eye perceives the onscreen image. But now that the response time has shrunk to a few milliseconds, it turns out that the You could have read in old reviews of LCD monitors (and in my reviews, too, as I have to confess) that as soon as their response time (the real response time as opposed to the specified value which, if measured according to ISO 13406-2, is not in fact indicative of the real speed) was lowered to 2-4 milliseconds, we would forget about it altogether just because its further decrease wouldn’t make anything better – we wouldn’t see the fuzziness anyway.
And finally such monitors are here. The latest models of gaming monitors on TN matrixes with response time compensation (RTC) technology have an average (GtG) response time of only a few milliseconds. I will put such things as RTC artifacts and inherent drawbacks of TN technology aside for now. What’s important is that the mentioned numbers are indeed achieved. But if such a monitor is put next to an ordinary CRT monitor, many people will say the CRT is still faster.
Strangely enough, it doesn’t mean we have to wait for LCD monitors with a response of 1 or 0.5 or less milliseconds. Well, you can wait for them, of course, but such panels won’t solve the problem. Moreover, they won’t differ much from today’s 2-4ms models because the problem is not about the panel, but about the peculiarities of the human vision.
Everyone knows about such a thing as persistence of vision. Take a look at a bright object for a couple of seconds, then close your eyes and you will be seeing a slowly fading-out “imprint” of the image of that object for a few more seconds. The “imprint” is rather vague – just the object’s contour – but it lasts as long as seconds! As a matter of fact, the retina retains a precise image of an object for 10-20 milliseconds after the object itself had disappeared. It’s only after that time that the image is fading out quickly, leaving just a contour if the object has been bright.
This effect comes in handy for CRT monitors. It’s thanks to this persistence of vision that we don’t notice the flickering of the screen. Phosphors in today’s cathode-ray tubes have an afterglow time of about 1 millisecond. The electronic beam makes its way through the whole screen in 10 milliseconds (at a scan rate of 100Hz). So, if our eye didn’t have any persistence, we’d see a light band, only one tenth of the screen in width, running from top to bottom. This can be easily demonstrated by photographing a CRT monitor at different exposure times.monitor’s speed – not its specified speed, but its subjective speed as it is perceived by the eye – is not all about milliseconds.