Vsync on LCD monitors

[Nadare]

Well, My question is how does vsync work on LCDs ?

My understanding of vsync on CRTs it that the frame changes while the scanning beam in the CRT is mid down the screen resulting in the top part of your screen being frame A while the bottom part of your screen being frame B, resulting in image 'tearing'.

Since LCDs dont have a scanning beam instead use pixels that have work on reponse time, how does vsync work on them, I would think since LCDs dont use a beam that the image would would change on the screen all at once, resuling in a skipped frame ??

Am I wrong ?
Whats really happening here ? I personally dont have an LCD myself so its hard to experiment.

 

[klah]

Originally posted by: Nadare

Since LCDs dont have a scanning beam instead use pixels that have work on reponse time, how does vsync work on them, I would think since LCDs dont use a beam that the image would would change on the screen all at once, resuling in a skipped frame ??

LCDs still draw the screen line by line and thus can exhibit the same tearing problems as CRTs.

Scroll down in This documentto see how the pixels are addressed and how signaling works in an active matrix lcd.

By scanning the gate bus-lines sequentially, and by applying signal voltages to all source bus-lines in a specified sequence, we can address all pixels. One result of all this is that the addressing of an AMLCD(active-matrix lcd) is done line by line.