Permanent magnet proximity switch

Claim 1

IN AN ELECTRICAL SWITCH OPERABLE BY A MAGNETIC ACTUATOR, THE COMBINATION COMPRISING: A SHELL; A COVER PLATE INTEGRAL WITH SAID SHELL, SAID COVER PLATE OF NON-MAGNETIC MATERIAL AND HAVING THREE APERTURES THEREIN, ONE OF SAID THREE APERTURES BEING SUBSTANTIALLY LARGER THEN THE OTHER TWO OF SAID THREE APERTURES, SAID APERTURES BEING ARRANGED TO FORM A GENERALLY QUADRANGULAR CONFIGURATION, AND AN INSERT OF MAGNETIC MATERIAL SEALED WITHIN EACH OF SAID THREE APERTURES; AN ARMATURE ROTATABLY MOUNTED WITHIN AND SUPPORTED BY SAID SHELL, SAID ARMATURE COMPRISING A BODY ELEMENT OF NON-MAGNETIC MATERIAL, AN ELONGATED PERMANENT MAGNET, A BLOCK OF UNMAGNETIZED MAGNETIC MATERIAL, AND A SWITCH ARM CARRYING A PAIR OF ELECTRICAL CONTACTS MOUNTED ON SAID BODY ELEMENT; TWO ELECTRICAL CONTACTS MOUNTED WITHIN AND SUPPORTED BY SAID SHELL; AND SAID ARMATURE SO CORRELATED TO SAID COVER PLATE THAT THE LARGER ONE OF SAID THREE INSERTS IS POSITIONED OVER SAID PERMANENT MAGNET AND SAID OTHER TWO OF SAID INSERTS ARE EACH POSITIONED OVER SAID BLOCK OF MAGNETIC MATERIAL, WHEREBY THE APPLICATION OF AN ORIENTED MAGNETIC FIELD OF A PREDETERMINED STRENGTH ACROSS SAID COVER PLATE WILL ACTUATE SAID SWITCH AND CAUSE ONE OF SAID PAIR OF ELECTRICAL CONTACTS ON SAID SWTICH ARM TO ENGAGE ONE OF SAID TWO ELECTRICAL CONTACTS SUPPORTED BY SAID SHELL.