When your Ubuntu laptop is running on battery, the screen will dim when it is idle in order to save power. This simple tutorial will show you how to stop the screen from dimming itself in Ubuntu laptop.

To get started:

First open System Settings from Unity Launcher, then click on Power icon under Hardware.

Then, uncheck “Dim screen to save power”

As an alternative, using Caffeine to disable screensaver also stop the screen from dimming in my Asus laptop.

Caffeine is a system applet that allows the user to temporarily inhibit both the screensaver and the sleep power saving mode, simply by clicking on it.

To install Caffeine, hit Ctrl+Alt+T, run following 3 commands in terminal:

sudo add-apt-repository ppa:caffeine-developers/ppa
sudo apt-get update
sudo apt-get install caffeine

The PPA supports Ubuntu 12.04, 11.10, 11.04, and 10.04.