Sony VAIO VGP-WKB5 Operating Instructions Manual page 9

To stop using the keyboard
Disconnect the receiver cable from the USB port of the computer.
You can disconnect and connect the receiver cable without turning off the
computer. You can save battery power by turning off the keyboard when
not in use.
Note
If another VGP-WKB5 wireless keyboard is being used nearby, it may interfere with
communication between the keyboard and the receiver. Enable communication at
different times or at a grater distance from the other wireless keyboard.
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