Position sensing devices, particularly in hoisting and conveying systems

Claim 1

A SYSTEM FOR DETERMINING THE POSITION AND DIRECTION OF MOVEMENT OF A MOVING OBJECT COMPRISING MEANS PRODUCING A MAGNETIC FIELD, SAID MEANS INCLUDING A FIRST STRUCTURE CARRYING MAGNETIC MATERIAL INFLUENCING SAID FIELD, POSITION-RESPONSIVE SENSING APPARATUS COMPRISING A FERROMAGNETIC STRUCTURE MAGNETIZABLE BY PROXIMITY TO SAID MAGNETIC FIELD, A MAGNETIC-FIELD RESPONSIVE HALL VOLTAGE MEMBER OF SEMICONDUCTING SUBSTANCES JOINED WITH SAID FERROMAGNETIC STRUCTURE FOR VARYING THE HALL VOLTAGE OF SAID MEMBER WHEN SAID FERROMAGNETIC STRUCTURE IS SO MAGNETIZED, THE SAID STRUCTURES BEING MOUNTED FOR RELATIVE DISPLACEMENT, SAID HALL VOLTGE MEMBER HAVING HALL ELECTRODE MEANS, AND AN ELECTRIC CONTROL CIRCUIT CONNECTED TO THE HALL ELECTRODE MEANS AND RESPONSIVE TO CHANGE IN HALL VOLTAGE CAUSED BY SAID RELATIVE DISPLACEMENT, SAID FERROMAGNETIC STRUCTURE COMPRISING A MAGNETIZABLE YOKE FORMED OF TWO SEPARATE MAGNETIZABLE LIMBS, EACH HAVING AN END POLE FACE, THE LIMBS FORMING A MAGNETIC CIRCUIT HAVING TWO OPPOSITE FLUX GAPS, A FIRST ONE OF SAID GAPS BEING IN A CENTRAL REGION OF THE YOKE, THE SECOND GAP BEING BETWEEN THE END POLE FACES, THE HALL VOLTAGE MEMBERS BEING A SEMICONDUCTOR PLATE HAVING ITS LARGE AREA FACES DISPOSED TRANSVERSELY OF THE FLUX PATH IN THE FIRST GAP, SAID MAGNETIC MATERIAL INFLUENCING SAID FIELD COMPRISING A MAGNET THAT TRAVERSES THE SECOND GAP, TRAVERSING OVER ONE END POLE FACE AND THEN OVER THE OTHER END POLE FACE, DURING SAID RELATIVE DISPLACEMENT, THE MAGNETIC AXIS OF WHICH MAGNET IS TRANSVERSE TO THE DISPLACEMENT PATH, THE TWO END POLE FACES OF THE YOKE BEING LOCATED IN A PLANE NORMAL TO THAT DEFINED BY THE FIRST GAP AND NORMAL TO SAID SEMICONDUCTOR PLATE, SAID DISPLACEMENT PATH EXTENDING IN FRONT OF SAID PLANE, THE MAGNET BEING A FLAT PLATE, THE DISPLACEMENT DIRECTION BEING IN THE PLANE OF THE PLATE, THE MAGNETIC AXIS OF THE PLATE BEING TRANSVERSE TO THE OPPOSITE FLAT SURFACES THEREOF, THE LENGTH OF THE PLATE IN THE DISPLACEMENT DIRECTION BEING GREATER THAN THE WIDTH OF THE SECOND GAP, TO OVER-LAP THE GAP DURING ITS DISPLACEMENT, SO THAT SAID HALL VOLTAGE PASSES FROM A POSITIVE MAXIMUM VALUE THROUGH A ZERO VALUE TO A NEGATIVE MAXIMUM VALUE DURING SAID TRAVERSE WHEN ONE OF SAID FIRST STRUCTURE AND SAID FERROMAGNETIC STRUCTURE MOVES RELATIVE TO THE OTHER IN ONE DIRECTION FROM A FIRST POINT ON ONE SIDE OF THE OTHER STRUCTURE TO A SECOND POINT ON THE OPPOSITE SIDE OF SAID STRUCTURE TO AND SAID HALL VOLTAGE PASSES FROM A NEGATIVE MAXIMUM VALUE THROUGH A ZERO VALUE TO A POSITIVE MAXIMUM WHEN SAID ONE OF SAID FIRST STRUCTURE AND SAID FERROMAGNETIC STRUCTURE MOVES RELATIVE TO THE OTHER IN THE OPPOSTIE DIRECTION FROM SAID SECOND POINT TO SAID FIRST POINT THEREBY INDICATING THE POSITION AND DIRECTION OF MOVEMENT OF THE MOVING STRUCTURE.