Time of answer of crystals liquids for transitions white man-black or gray-gray, effect wake and techniques of improvement of "the perceived" time

As famous the mechanism of operation of a screen to CL is based on the fact that, it orients to you in opportune way, the CL can concur or less the passage of the coming from light from the retroilluminazione of the panel; the time of answer total is in kind defined like the time necessary to the CL in order to pass from one be "all closed" (black) to one "all open" (white man), in order then to return to the "all closed one". However some producers measure alone the bianco>nero passage (or viceversa) to which they achieve therefore lower values of time. Moreover, it is not said that the bianco>nero passage has the same duration of the passage nero>bianco. In truth, this often boasted value from the producers is not indeed meaningful, in how much it is rarest that in filmato steps from the white man to the black one (or viceversa): very more frequent it is that steps from a shading of gray to an other and the times for the transitions gray-gray (G2G) are generally longer than that white man-black.Today sovravoltaggio) of panels CL is in correct part this slowness on the gray-gray by means of techniques of "overdrive" (, to the cost but of an increase of the noise of the images and/or sometimes of a reduction of riproducibili colors (6 bit rather than 8, simulates to you then through techniques of dithering).

The so-called "effect wake" that often comes attributed to panels LCD is in truth by now only in riferibile part to the time of answer of the CL: in part it is in fact to charge itself to the persistence of the vision on the hairnet, that is depends on the physiology of the human eye[necessary citation]. In fact, the perception of the effect wake also is tied to the fact that panels LCD maintain the image between frame and an other and are retroilluminati in continuous, with the exception of a traditional cathode-ray tube in which the image it is "reconstructed" to the frequency of refresh of screen (50 or 100 Hz the TV; from 60 until 120 Hz a monitor for PC). In other words, while the phosphorus of a CRT alone stretch "to extinguish themselves" endured after the passage of the electron paint-brush , in a LCD-TFT (like in all the screen to active matrix, put molding on and OLED) the pixel conserve the brightness "until new order", that is until the successive photogram of the filmato one. This is a great advantage for a screen PC (the image is stable and not sfarfalla), but it becomes a problem with images (TV, film in motion): every photogram turns out in fact in part overlapped to the previous one to cause is of the slowness of the CL to change be, is to the persistence of the vision on the hairnet. Of fact also with a theorist LCD with instantaneous time of answer a sure effect would be always present wake[necessary citation]. The solutions currently on the market are substantially three, commercially often joined (also improperly) from diciture type 100Hz: paradoxicalally such several solutions always do not have to that to make with 100Hz of the CRT and indeed the someone they try to imitate the operation of a classic CRT to 50Hz. Such effect comes obtained by means of the intercalamento of completely black pictures, interpolated intermediate pictures "calculate to you" from the electronics of the screen or by means of the short sequenziali extinctions of the lamps of retroilluminazione (realizing one risen of "luminous scansion" of the screen); for obvious reasons the constructors are restii - in some cases to supply precise indications on the precise operation of these technical new. Some of these solutions could determine an increase of the perception of sfarfallamento of screen LCD.