What happens when an LCD screen turns black/shuts off?
First the backlight is turned off to mask what happens next. Then either the crystals are driven in idle state if possible to gracefully shut it down and then the screen refresh is stopped. Otherwise the screen just fades away when refresh stops. It depends on whether you actually push the standby button so the device shuts nicely or if you just pull the plug. Anyway, it should not consume power during standby.