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Message #73561 of 126777
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Date: 2005-03-06
From: Russell McMahon
Subject: [EE] IBM laptop anti-drop protection.

I see IBM advertising that their Thinkpads have "drop sensing" which 
parks the drive when the laptop senses that it has been dropped. May 
have had this for years for all I know.

I assume that sensing is done with several accelerometers - an XYZ 
cluster would be needed to work in all orientations. When the vector 
sum of acceleration falls to near zero it's time to shut down.

They say that head parking time is 500 mS. For a straight clean drop 
that's a 1.25m fall :-(. Too far. To get distance down to 600 mm you 
need about 350 mS parking.

Has anyone encountered this system yet? Any idea of how it works in 
practice and how effective it is? It should really scream when dropped 
and before impact to instil user confidence :-).


        RM 

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