Position tracking system using a radiation director which directs

Abstract

A radiation source directs radiation toward a radiation sensor in such a way that the intensity of radiation sensed by the radiation sensor alternates in a periodic manner as the radiation source moves radially relative to the radiation sensor. The radiation sensor generates either a '1' or a '0' depending upon whether the intensity of the radiation sensed by the radiation sensor is above or below a particular reference value. Thus, the angular position of the radiation source relative to the radiation sensor is indicated by an alternating series of '1's and '0's. A multi-bit binary value which indicates the absolute position of the radiation source relative to the radiation sensor can be generated. In this case, a band of radiation is directed toward the radiation sensor. The radiation band is separated into a plurality of portions, the intensity of each successive portion being twice the frequency of the preceding portion. Each portion of the radiation band impinges upon a corresponding sensor. The signal generated by each sensor element is thus one bit of a multi-bit binary value which varies as the radiation source moves radially relative to the radiation sensor.