Switch off the backlight on Ibook

[Thomas Champagne]

Hi

I have an IBook : http://support.apple.com/specs/ibook/iBook_G4_Late_2004.html.
I have installed Ubuntu (Hardy) on it but I have a problem when my
computer is standby. The screen is black but the backlight is always
on. I think the problem come to hal because hal support PMU and I
think PMU can switch off the backlight.

Tell me how can I help hal to switch off the backlight of my computer
when it is in standby.

Regards
Thomas

PS : Sorry for my poor english !