FREE FALL SENSOR

摘要

A free fall sensor for detecting a falling state of portable electronic equipment such as notebook personal computers includes a movable electrode including a plurality of moving portions disposed on a circumference at regular intervals so as to be equidistant from a central axis, a fixed electrode disposed outside the movable electrode so as to be brought into contact with and separated from the movable electrode, an inertial member located inside the moving portions of the movable electrode, and a buffer preventing the inertial member from contacting the fixed electrode so that the moving portions serving as movable electrodes are held between the fixed electrode and the inertial member thereby to be prevented from being pressed or rolled. The central axis makes a right angle with a direction of gravity. The inertial member normally deforms the movable electrode elastically by a weight thereof so that the moving portions are brought into contact with the fixed electrode, whereupon an electric circuit is made. Upon fall, the moving portions return the inertial member by the elasticity thereof and the moving portions are separated from the fixed electrode such that the electric circuit is opened.