Patent ID: 6348790
Filing Date: 2002-02-19
Classification: G01P

Abstract:
A leadless motor rotation detector apparatus for determining the direction of shaft rotation of a motor providing a fluctuating magnetic field when rotating, said apparatus comprising:at least two sensors separated a predetermined distance D1 from one another, each said sensor operative for sensing said magnetic field and generating a corresponding sensor signal having an amplitude and phase associated with said sensed magnetic field; and a processor responsive to said sensor signals for comparing temporal aspects associated with the relative phase of each of said sensor signals to determine a leading or lagging signal, said leading or lagging signal associated with a corresponding one of said at least two sensors and indicative of the direction of motor rotation, wherein said sensor signals are substantially sinusoidal waveforms and wherein said processor includes; means for determining zero crossing points associated with each of said sensor signals; means for determining first and second time differences associated with said zero crossing points, wherein said first time difference is associated with the time interval between the first zero crossings of said sensor signals and wherein said second time difference is associated with a first zero crossing of one of said sensor signals and a second zero crossing of the other sensor signal.