LG 42LN5204.AEU User Manual page 53

To set Automatic Standby
❐
SETTINGS ➾ TIME ➙ Automatic Standby
[Depending on model]
If you do not press any button on the TV or remote control for a certain period,
the TV will automatically switch to standby mode.
✎ This function does not work on Store Demo mode or while software update.