Ubuntu 19.04 GNOME
When I lock my computer screen turns off for a shot period. How to disable this?
I found an alternative solution for these problem.
Option One
Try replacing the default screensaver with another one, like xscreensaver.
Option Two
When you manually lock your screen, just hold the buttons a second longer and the screen won't turn off.
Source Link: https://stackoverflow.com/a/52110833/10711557