LG K540 User Manual page 39

Available setting items may vary, depending on the selected screen
lock method.
KnockON
You can turn on or off the screen by double-tapping the screen.
This option is available only on the Home screen provided by LG. It
may not function properly on a custom launcher or on the Home
screen installed by the user.
When tapping the screen, use your fingertip. Do not use a
fingernail.
To use the KnockON feature, make sure that the proximity/light
sensor is not blocked by a sticker or any other foreign substance.
Turning on the screen
Double-tap the middle of the screen.
Tapping the top or bottom of the screen may decrease the
recognition rate.
Turning off the screen
Double-tap on an empty space on the Home screen.
If a screen other than the Home screen is displayed, double-tap on
an empty space on the status bar.
Basic Functions
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