Screen off when "docked"

Hey everyone! I got a Samsung Galaxy Note 2 N7100 running the 4.1.2 Android version and I've just bought a "GalaxyNote2 to HDMI" gadget which let me watch movies in the phone directly on TV using a HDMI cable. It works really good but when I am watching a movie from the phone on my TV I notice that the screen of the phone stays ON all the time.

So I would like to know if one of you knows if it is possible to keep the phone screen turned OFF while the phone is pluged to my TV via HDMI cable.

Thank you since now!
-Peace to you all.