GB792176A - A variable position detecting device - Google Patents

Abstract

792,176. Electric measuring systems. LICENTIA PATENT - VERWALTUNGS - GES. May 25, 1955 [May 26, 1954], No. 15042/55. Class 40 (1). A device for measuring the displacement of a body from a datum position comprises two permanent magnets 3, 4, Fig. 1, held inside an iron ring 2 by a non-magnetic spacer 7 and polepieces 5, 6 and associated with a first armature 11 pivoted at 10 to swing between contact stops 12, 13 and a second armature 8 slidable between the polepieces 5, 6. In operation, with armature 8 initially central, armature 11 is made to swing by energizing a stationary coil 14 from an A.C. source 32, Fig. 3, the time of dwell on each contact 12, 13 being made equal by a D.C. biasing current from a battery 31, and indicated by zero resultant current in a meter 40 connected to the armature 11. If armature 8 is now displaced relative to the polepieces 5, 6 the flux distribution is changed so that the times of dwell of armature 11 at contacts 12, 13 become different, and meter 40 will give a reading indicative of the extent and direction of the movement of armature 8. Contacts 12, 13 may be associated with additional relays and signalling circuits.