Omron HR-310 - Manual (Page 23)

23
BACKLIGHT / KEYPAD LOCK
To turn the backlight on for 3 seconds:
Press . (Press again within the 3 seconds to extend the light
for 3 more seconds.)
To turn the keypad lock ON or OFF:
Press and hold .
appears when the keypad lock is ON.
NOTE: The backlight does not work when the low battery icon
is shown and will return to normal once the batteries are
replaced.