Just found out the display can be turned off on the DL100:
The dimmer menu is the one, that displays 'OFF'!
Then turning the knob and the timer from 5 - 30 s can be set.
According to strange asian logics, they do not show the display status, which for us Europeans inuitively would be 'ON', but the timer status. So 'OFF' means the display is always on.
Very much like on our Toyotas: amazing cars, but locking the door, means to turn the key AWAY, anti-clockwise, from the lock...
Oh, these Asians... (Adapted from Boney M., Rasputin)