android stay awake display setting
From thelinuxwiki
The simplest way to keep your Android phone lit up at home, whether it's on a dock or plugged into your PC, is to tell it to avoid turning off its display anytime it's connected to an external power source.
This option's in a slightly obscure place: From your home screen, press your phone's "Menu" key, then select
Settings >> Applications >> and Development
There, you'll see an setting called "Stay Awake." Activating that option will prevent your display from timing out anytime the phone is running on nonbattery power.