backlight / lcd question

[accorn]

Hi,
Regarding the backlight on the h3150:
Is the internal backlight on all the time on this unit, just on brightly when you press he power button, and on lowly under most conditions? Or, is the internal backlight completely off until you turn it on with the power button, and otherwise the screen is just illuminated from external sources?
I ask because internal backlights give me headaches, so i'm hoping it is 100% off unless I turn it on.

[Adama D. Brown]

I'm fairly certain it can be toggled on and off at the user's discretion.