Patent ID: 6043646
Filing Date: 2000-03-28
Classification: H03K

Abstract:
A proximity switch, comprising:a U-shaped permanent magnet with a vertical direction of magnetization, said permanent magnet defining a magnetic flux-free region formed by three like mutually repelling poles and positioned between limbs of the U-shaped magnet;a magnetic field-sensitive sensor positioned in said magnetic flux-free region between said limbs and inwardly of terminating ends of said limbs, said flux-free region having a longitudinal extent substantially perpendicular to a magnetic pole axis of each of said limbs;a flat ferromagnetic triggering part positionable closely above said limbs of the U-shaped magnet in a plane parallel to a base of the U-shaped magnet; anda switching signal triggered from the sensor by at least partial cancellation of the magnetic flux-free region when the triggering part is brought close to poles of said limbs of the U-shaped magnet, the switching signal being capable of evaluation to indicate activation of the proximity switch.