How to Set the Lock Time-out on the Nexus 7 Tablet
You can manually lock the Nexus 7 tablet at any time by pressing the Power Lock key. That’s why it’s called the Power Lock key. When you don’t manually lock, the tablet automatically locks itself after a given period of inactivity. How long? That’s up to you, though the Nexus 7 is preconfigured to snooze (self-lock) after ten minutes of your ignoring it.
To set the time-out to something other than ten minutes, obey these steps:
At the Home screen, touch the All Apps icon.
The icon is found at the bottom center of the touchscreen, as shown in the margin.
Choose Settings to open the Settings app.
You may have to swipe the screen to the left to find the Settings app icon.
Choose Display and then Sleep.
Choose a time-out value from the Sleep menu.
The range is from 15 seconds to 30 minutes at various intervals.
Touch the Home icon to return to the Home screen.
The lock timer begins after a period of inactivity, when you don’t touch the screen or the timer starts ticking. About five seconds before the time-out value you set (refer to Step 4), the touchscreen dims. Then it turns off, and the screen locks. If you touch the screen before then, the timer is reset.