Tilt Alarm Insensitive to Mounting and Low Frequency Motion
Original Publication Date: 1983-Oct-01
Included in the Prior Art Database: 2005-Feb-07
There is a need to protect automatic teller terminals, point of sale terminals, and the like from break-in or burglary. Accordingly, it is desirable to set off an alarm when the terminal is tilted. Low frequency motion caused by building sway or static terminal tilt should not falsely set off the alarm. This disclosure uses two pendulums, as shown in the drawing, having different periods of oscillation to keep a reed switch mounted on one pendulum and a magnet mounted on another pendulum together at normal terminal position and during low frequency building sway. Abrupt jars or large tilt angles, however, will separate the magnet from the reed switch, allowing the circuit to open and set off the alarm.