| 摘要 |
A positional information generating apparatus comprises a code disposed on a main track on which M-sequence codes form a cyclic code of different code words, and sensors disposed for attaining relative movement with reference to a direction of the main track. The code word is detected from the main track by the sensors for generating positional information. A sensor array for the main track in which a greater number of sensors than the number of elements of a code word are disposed over a span corresponding to a length of one code word in such a way that at least one sensor is located on each code element to define a code word to be read. A relative position detector is provided for detecting a relative positional relationship between the sensor array for the main track and the main track. A sensor selecting circuit selects a sensor for each code element from the sensor array for the main track, which is in a position to detect the code element, based on the detection signal from the relative position detector, and allows transmission of the detection signal from said sensor. A main track includes a cyclic code of different code words disposed thereon, and a sub-track includes discrimination elements arranged cyclically along the main track.
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