| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect the angle of rotation and to reduce calculation error even when using a signal producing means with relatively low accuracy. SOLUTION: In a learning step, each time interval Tn is measured from a base point when a detection signal S2 is output from an optical sensor 10 during constant speed revolution to the point of sequential outputting of zero-cross detection signal S4 from a zero-cross point detection circuit 15, and a learned angleθn obtained by converting the measured time interval Tn to an angle is stored in a memory 20. In later detection steps, count values N(θn) corresponding to the learned angleθn corresponding to the zero-cross detection signal S4 are set to an angle counter 24 at every output of the zero-cross detection signal S4. Between the zero-cross detection signals S4, the angle counter 24 counts clock signals S6 having a frequency according to angle variation rate in a period immediately before calculating with an angle variation rate calculator 26. COPYRIGHT: (C)2006,JPO&NCIPI
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