| 摘要 |
An apparatus for sensing the absolute angular position of a rotatable shaft comprising one or more screw threads on the shaft or a screw-threaded shaft mechanically linked to the rotatable shaft so as to rotate in predetermined relationship to the rotation of the rotatable shaft, a permanent magnet, and an array of preferably four equally axially spaced magnetic field sensors positioned between the screw thread and the magnet along a line parallel to the axis of the screw-threaded shaft and at a distance apart of less than the thread pitch divided by the cosine of the helical angle, and positioned close to the screw thread. A determination of the instantaneous magnetic field strength between each sensor and the screw threads enables a computation of the radial distance between the sensor and the screw threads; together, the array of sensors establish preferably four discrete radial distance measurements from which the absolute angular position of the shaft can be computed using previously known signal processing circuitry and computations. -31-
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