NEC 1980FXi - Manual (Page 24)

English-22
If Brightness setting value becomes higher than the Brightness setting vale at the bright condition while user sets the
Brightness at the dark condition, Brightness setting becomes as following figure.
BRIGHTNESS range
when Y reach to X
BRIGHTNESS range
when user up the Brightness further
BRIGHTNESS range
when user down the Brightness again
BRIGHTNESS range
BRIGHTNESS range