Transducer assembly for an electronically monitored mechanical pipette

摘要

The present invention relates to an electronically monitored mechanical pipette which includes a transducer assembly for monitoring the rotational movement of a volume delivery adjustment mechanism of the pipette. The transducer assembly preferably includes at least two Hall-effect transducers spaced 90 rotational degrees apart from each other and sense the magnetic field of an annular magnet attached to the delivery adjustment mechanism. The Hall-effect sensors produce sinusoidal signals which are 90 DEG out of phase from each other when the magnet rotates relative thereto. The two out of phase sinusoidal signals are processed by an electronics assembly of the pipette to determine the absolute position of the volume delivery adjustment mechanism and compute a fluid volume delivery setting of the pipette. The transducer assembly in conjunction with the electronics assembly monitors both the number of revolutions of the volume delivery adjustment mechanism from an initial zero position, but also the position of the volume delivery adjustment mechanism within a revolution.