초록 ▼

Apparatus for detecting a tooth of a body. The tooth has an edge terminating in a notch. The tooth and notch are disposed along an edge of the body. The apparatus includes a pair of Hall effect cells disposed adjacent to, and laterally disposed along, the edge of the body. A magnet is positioned to

Apparatus for detecting a tooth of a body. The tooth has an edge terminating in a notch. The tooth and notch are disposed along an edge of the body. The apparatus includes a pair of Hall effect cells disposed adjacent to, and laterally disposed along, the edge of the body. A magnet is positioned to provide a magnetic field through the edge of the body and Hall effect cells. The magnitude of field passing through the Hall effect cells is related to the relative position between the tooth and Hall effect cells. The Hall effect cells produce an output voltage related to magnitude of magnetic field passing through the cell. A differencing circuit is fed by the pair of Hall effect cell produced voltages for producing a difference signal having a peak when the edge of the tooth is positioned between the pair of Hall effect cells. A peak detector detects the peak produced by the difference signal. A threshold circuit is fed by the differencing signal for producing a gating signal when magnitude of the difference signal exceeds a threshold level. The gating signal enables peak detector produced pulse to pass to an output of the apparatus and inhibits such detected peak from passing to the output in the absence of such gating signal. A threshold level adjusting circuit is responsive to the difference signal for tracking maxima in the difference signal and establishing the threshold level of the threshold circuit in accordance with the tracked difference signal maxima.

대표청구항 ▼

[ What is claimed is claimed:] [1.] Apparatus for detecting passage between a point on a body and a reference position, comprising:a pair of magnetic field sensors disposed laterally along a direction of movement between the body and the reference position;a magnet disposed at the reference position

[ What is claimed is claimed:] [1.] Apparatus for detecting passage between a point on a body and a reference position, comprising:a pair of magnetic field sensors disposed laterally along a direction of movement between the body and the reference position;a magnet disposed at the reference position to provide a magnetic field through the body and the pair of magnetic field sensors, the magnitude of the field passing through the body and the pair of sensors being related to the relative position between the point on the body and the reference position, each one of the sensors producing an output signal related to the magnitude of the magnetic field passing such sensor;a differencing circuit fed by the output signal produced by each one of the sensors for producing a difference signal having a peak when the point of the body is positioned between the pair of sensors;a peak detector for detecting the peak in the difference signal and for producing a peak detection signal indicating detection of such peak;a threshold circuit fed by the differencing signal for producing a gating signal when the magnitude of the difference signal exceeds a threshold level;a gate, the gating signal enables the peak detector produced peak detection signal to pass through the gate to an output of the apparatus when the gating signal indicates the magnitude of the difference signal exceeds the threshold such peak detection signal being inhibited from passing through the gate to the output of the apparatus in the absence of such gating signal; anda threshold level adjusting circuit for establishing the threshold level in accordance with the magnitude of the difference signal.