I am glad to see your post as I am getting frustrated with the amount of time I have to enter my lock pattern . . .seems like unless I am right on top of entering the lock pattern my phone goes dark. I scoured the settings, but didn't see anything. Hoping smarter people than me on this forum have a way to extend the unlock time. Thanks for posting.
I use the pattern code and it is just 4 "buttons", but oftentimes when I am not paying total attention (some call it multitasking) to entering the unlock code it goes to a dark screen before I can enter it. . .I guess I will just have to pay closer attention