India Broadband Forum

lcdmonitor

LCD tv ...

The pictures on a CRT TV / Monitor do not exhibit any sort of "ghosting," because the CRT's phosphor, charged by the strike of electrons, emits most of the light in a very short time, under 1ms, compared with the refresh period of e.g. 20 ms (for 50 frame/s video). In LCDs, each pixel emits light of set intensity for a full period of 20 ms (in this example), plus the time
it takes for it to switch to the next state, typically 12 to 25 ms.

Video material, shot at 50 or 60 frames a second, actually tries to capture the motion. When the eye of a viewer tracks a moving object in video, it doesn't jump to its next predicted position on the screen with every refresh cycle, but it moves smoothly; thus the TV must display the moving object in "correct" places for as long as possible, and erase it from outdated places as quickly as possible. LCD televisions are also a good component for video games.

Although ghosting was a problem when LCD TVs were newer, the manufacturers have been able to shorten response time to 2ms on many computer monitors and around an average of 8 ms for TVs.

LCD technology is based on manipulation of polarized light. Two thin polarizing sheets are laminated to two glass substrates containing a thin layer of liquid-crystal. A regular 2-dimensional grid of electrodes allows each pixel in the array to be selected and activated individually. Several LCD technologies are used for the realization of large format television screens
(e.g. TN, IPS, PVA, FFS), all in combination with active-matrix addressing.

It had been widely believed that LCD technology was suited only to smaller sized flat-panel televisions at sizes of 40" or smaller. Early LCDs could not compete with plasma technology for screens larger than this because plasma held the edge in cost and performance. However, LCD TVs can now offer acceptable performance in larger sizes....