Ubuntu – Disable lock screen dimming in 16.04

I seem to have found the cause of the problem, as well as the solution; apparently,there was some strange power management package installed.

I noticed a few weeks ago that the hard drive was powering down after three or four seconds (literally) of inactivity. So, after attempting to remedy the hard drive issue using the software from THIS page, I get a message telling me that tlp can't start because of a package called laptop-mode-tools, as well as a recommendation to remove it.

So, I powered up another Ubuntu laptop, which hasn't given me any real problems, and checked to see if it had that same package (using sudo apt-get purge laptop-mode-tools -s), and found that said package didn't exist, which made me assume it probably isn't particularly necessary. After removing both packages (that is, tlp and laptop-mode-tools), and rebooting the system, the both hard drive spin-down, and the dimming screen issues were solved.

Ubuntu 16.04

I have also been trying to figure out how to stop the lock screen from dimming. I can not seem to find anything associated with the screen dimming when going to the lock screen that I can edit/tweak.

I tried all the usual suggestions of

gsettings set org.gnome.desktop.screensaver idle-activation-enabled false

gsettings set org.gnome.desktop.session idle-delay 0

gsettings set org.gnome.settings-daemon.plugins.power idle-dim false

but none of them worked.

**** WORKAROUND ****

However invoking an activity once the dimming starts seems to then follow what ever settings you have enabled in the system settings > Brightness & Lock > settings.

The way you can stop it is by locking the screen then typing a few random characters into the password prompt. It will now no longer dim.