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Fn + F6 - backlight turns off immediately, image stays (visible if shine something at the display)

xset dpms force {off,suspend,standby} - backlight turns off slowly, image cleared.

How to programmatically just turn off backlight on Acer Extensa 5220 laptop in Linux? It should work fast and should not touch image (unlike xset method).

Ideally if I could rapidly switching backlight off and on emulate lower_than_minimum brightness level (ideally - to be hardly visible (but visible) at night).

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The utility to control the backlight under X is called xbacklight. Unfortunately, it doesn't always work, depending on how well your video card is supported.

You may have more success with a driver-specific utility. For ATI cards, try radeontool. For NVidia cards, try nvidia-settings. There may be a similar utility for Intel cards.

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I have Intel card in laptop. – Vi. Jul 13 '10 at 17:08
xbacklight can only edit brightness (with lowest brightness limit). It can't turn on/off it. – Vi. Jul 13 '10 at 17:10
up vote 0 down vote accepted

If you have Acer laptop, use script to control laptop's Embedded Controller. := 84 00 will turn off backlight on my laptop

Warning Before using acer_ec on other laptop check that 84'th register is that you need. The script looks like one that can permanently damage the device if used without caution.

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