Keeping my Legend active.

[Guest oldun]

To use my Legend I must quickly press the on/off button to activate the screen, drag my finger down the screen and then draw in the necessary pattern.

I have no problem with this and it is not the reason for my post.

The problem I have is that after about 20 seconds without input the screen switches off and the phone goes back to sleep.

Can I increase the time the phone remains awake?