Disable autobrightness on Ideapad U460s in Ubuntu
Use Windows, or block it with something.
Open the lenovo energy management (via the battery touch sensitive button) then click on the gear icon between "i" and "?" and click on smart control tab and uncheck ALS (Ambient Light Sensor)
the settings for brightness settings for battery and A/C plugged in can be changed here (Lenovo Energy Management) for each power scheme (click on the power scheme then click on the gear on the right) and you can change the settings in there.