How to default turn off the screen

Hi, all!
I am running the Openwrt which build with kmod-tg3 and kmod-phylib-broadcom on my notebook computer Acer 4741G(I3-380,BCM57780,AR5B97), I want to keep the screen off when the openwrt running, what should I do?

I would just close it.

(Routers have screens now? :wink:)