[OT?] Refresh rates for LCD screens?

I know this is nothing to do with image processing but I'm pushing my
luck and am confident that someone here will set me straight. The
answer has been surprisingly and frustratingly hard to find.

My model for CRT displays has a display processor scanning through
image pixel memory cells in raster order and sending grey level values
through a digital to analogue converter to produce a voltage which
somehow modulates the flow of electrons from an electron gun onto
phosphor painted on the rear surface of the front of the tube; scan
signals are generated accordingly. For colour, multiply everything by
three and include shadow masks and red, green and blue phosphor
patches.

What is an equivalent refresh model for LCD screens? Assume analogue --
though I might need an exact explanation of the difference between
analogue and digital in this context.

I know that LCD screens have a 'native' resolution, i.e. that each
screen pixel corresponds to a single transistor or diode.

Do we still have raster refresh? I guess flicker and tearing do not go
away when we have an LCD screen.

Another question. If 25--30 Hz is good enough for television or movies,
why the need for 70--85 Hz refresh on computer screens?

Plus, maybe I should ask whether the answer for LCD will do also for
TFT and plasma?

TIA,

Jon C.

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