Turn off screen, but not Suspend

Question

I have a 16.04 laptop monitoring my IoT stuff. It is constantly Rx/Tx a stream of data via the Serial port and an Arduino Mega. All works great.

I'd like the screen to go black after a period of no keyboard acitivity, but not suspend as that also suspends the data stream.

I know I can set the screen to never turn off in Settings with "Turn screen off after ..." and set it to "Never," to prevent the suspending but that leaves the system security open.

When I need to access that laptop, maybe days later, I want to have to login-screen available before getting the data-screen back again.

How do I do that?

Thank you.

Answer 1

To prevent suspension change: all settings>power>Suspend when inactive for

To allow screen off, change: change all settings>brightness & lock>turn screen off when inactive for

To lock after a certain period or on screen off, change: all settings>brightness & lock>Lock screen after

Answer 2

On Ubuntu 22.04 it looks like the "Brightness & Lock" settings sub-menu mentioned by SillyInventor has been removed. And unfortunately the two screen-off settings Power->Power Saving Options->Screen Blank and Privacy->Screen->Blank Screen Delay are actually the same setting, just available in two places [change one, the other changes]. So best bet to save a little power while inactive is to Power->Power Saving Options->Dim Screen. In my case (on a Dell Inspiron) sometimes the auto-suspend option results in the system not booting up, so I have to just leave the screen blank settings to Never rather than 15 minutes or something.

Also, I suspect this may be a Dell problem because when I used Windows 10 on this same laptop, I could never put it to sleep or half the time it wouldn't wake up.