>       What aboat those special driving voltages that are needed in
>       LCD? I haven4t yet done much research to know how LCD4s actually
>       work, but I think the driver sends some kind of A.C. voltage.
>       Wether it4s sine- or square wave, I don4t know..

If you are not multiplexing LCD's, the driving waveform for a lit LCD segment
is simply a square wave that goes between [positive some voltage] and [nega-
tive some voltage], relative to the common terminal.  The simplest way to get
this is to drive the common wire with a 5-volt square wave and drive the seg-
ments either in-phase or out-of-phase.

If you are using a multiplexed display, it's desirable to be able to drive
segments with different voltage levels so as to eliminate "bleed-through"
effects; unlike an LED, an LCD does not act as a diode so you definitely
have to worry about balancing all the voltages on the matrix.  I'll write
more on this if you're interested, but I don't have time right now.