Magnetic sensor and circuit for detecting the edge of a target as it passes the centerline of the sensor
First Claim
1. In a magnetic sensor for detecting a ferrous target separated from the sensor by a gap, the sensor having a centerline and means for providing an analog signal representing the rate of change of magnetic flux in the gap as the target passes the sensor moving generally at right angles to said sensor centerline, the target having an edge extending transverse to the direction of relative movement and in the direction of the sensor centerline, means for detecting alignment of an edge of the target with the centerline of the sensor comprising:
- means for differentiating said analog rate of change signal, the analog differentiated signal having a zero crossover point corresponding to the time at which said edge of the target passes the centerline of the sensor; and
means for detecting the zero crossover point of said analog differentiated signal to provide an output signal which corresponds to the time at which the target edge is conincident with the centerline of the sensor.
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Accused Products
Abstract
A magnetic sensor for detecting the leading edge of a ferrous target as it passes the centerline of the sensor. The magnetic sensor includes a coil output representing the rate of change of magnetic flux as the target passes the sensor. The coil output is differentiated to provide a signal having a zero crossover point corresponding to the time at which the leading edge of the target passes the centerline of the sensor. The differentiated signal is applied to a zero crossover threshold detector to provide a first pulse, the trailing edge of which corresponds to the time at which the target'"'"'s leading edge is coincident with the sensor centerline. Additional means provide a second pulse whose leading edge corresponds to the time at which the leading edge of the target is coincident with the centerline of the sensor.
19 Citations
9 Claims
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1. In a magnetic sensor for detecting a ferrous target separated from the sensor by a gap, the sensor having a centerline and means for providing an analog signal representing the rate of change of magnetic flux in the gap as the target passes the sensor moving generally at right angles to said sensor centerline, the target having an edge extending transverse to the direction of relative movement and in the direction of the sensor centerline, means for detecting alignment of an edge of the target with the centerline of the sensor comprising:
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means for differentiating said analog rate of change signal, the analog differentiated signal having a zero crossover point corresponding to the time at which said edge of the target passes the centerline of the sensor; and means for detecting the zero crossover point of said analog differentiated signal to provide an output signal which corresponds to the time at which the target edge is conincident with the centerline of the sensor. - View Dependent Claims (2, 3, 4, 8)
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5. In a magnetic sensor for detecting a ferrous target separated from the sensor by a gap, the sensor having a centerline and means for providing an analog signal representing the rate of change of magnetic flux in the gap as the target passes the sensor moving generally at right angles to said sensor centerline, the target having an edge extending transverse to the direction of relative movement and in the direction of the sensor centerline, means for detecting alignment of an edge of the target with the centerline of the sensor comprising:
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means for differentiating said analog rate of change signal; and means for comparing the analog differentiated rate of change signal to a reference signal to provide an output pulse having an edge corresponding to the time at which the target edge is conincident with the centerline of the sensor. - View Dependent Claims (6, 7, 9)
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Specification