Magnetically actuated sensor with reed contact e.g. for detecting open state of door or window has security reed contacts for monitoring external magnetic fields

摘要

A magnet (M) moves along a path parallel to the longitudinal axes of the sensor reed contact (MK), at a predetermined distance from the surface of the sensor. Beside or below the reed contact, at least one security reed contact (SK2,SK3) is provided to monitor external magnetic fields. The magnetic response beam of the security reed contact extends into the space (ZR) between the path of movement of the magnet and the surface of the sensor, but not into the path of movement itself.