Speed sensor for stepped rotation of shaft - uses integrated hall effect sensor with Schmitt trigger circuit providing digital output

摘要

A wheel (1) is fixed onto a shaft (2) whose rotational speed is to be measured. The wheel has several permanent magnetic pole elements around its periphery. These successive pole elements are of alternate magnetic pole polarity. A fixed detector (3) is positioned facing the peripheral surface of the wheel. This detector contains a linear Hall effect detector which is integrated on a common substrate with a Schmitt trigger circuit (5) to form a hybrid circuit of thick and thin film component technologies. Compensating components are mounted on these circuits. The Schmitt trigger provides a digital output signal each time the Hall effect detector senses a zero value.