Setting Display Timeout
Set the display to turn itself off when no activity is detected for a specified time.
Find the Feature | M > Settings > Initial Setup | 
  | > Display Timeout | 
Setting Up Your Phone - 51
Set the display to turn itself off when no activity is detected for a specified time.
Find the Feature | M > Settings > Initial Setup | 
  | > Display Timeout | 
Setting Up Your Phone - 51