Hall effect position detector using a single permanent magnet
AssigneeU.S. Philips Corporation
InventorsJean-Pierre Ricouard, Bruno Schorter
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Abstract
A device for detecting specific positions of a moving part, for example a rapidly rotating part provided with soft-magnetic projecting elements which alternately pass close to the detector device, which comprises a stationary magnetic exciter circuit for a Hall-effect crystal. The magnetic exciter circuit comprises a single permanent magnet having one pole face oriented towards the moving part, and provided with two symmetrical soft-magnetic pole pieces forming a narrow gap in which the Hall-effect crystal is disposed.
Claims10
A Hall-effect position detector comprising a Hall-effect crystal, a stationary magnetic exciter circuit for the Hall-effect crystal which exciter circuit has an axis of symmetry, the exciter circuit being arranged to cooperate with a movable part movable in the immediate proximity of said detector and which comprises soft-magnetic elements which during their movement are respectively and alternately situated on either side of the axis of symmetry with a trailing end of one soft-magnetic element situated on one side of said axis substantially coinciding with a leading end of a soft-magnetic element situated on the other wise of the said axis of symmetry, the magnetic exciter circuit comprising a single permanent magnet having one pole face oriented towards the movable part and provided with two symmetrical soft-magnetic pole pieces on said pole face arranged to cooperate with said movable part and between which a narrow gap is formed in which the Hall-effect crystal is disposed on said axis of symmetry.
A position detector for determining the position of a moving part comprising, a Hall-effect crystal, a stationary magnetic circuit for exciting the Hall-effect crystal including a single permanent magnet having a first pole face provided with two symmetrical confronting soft-magnetic pole pieces forming a narrow gap along an axis of symmetry of the magnetic circuit in which gap the Hall-effect crystal is disposed so as to be subject to a magnetic excitation field produced therein by the permanent magnet, said moving part comprising first and second soft-magnetic elements movable in close proximity to said two pole pieces and respectively located on opposite sides of said axis of symmetry with each soft-magnetic element having a leading end and a trailing end and arranged so that a trailing end of one element coincides with a leading end of the other element.
Dependencies are inferred from the claim text.