SHAFT RUN-OUT INSENSITIVE TYPE OPTICAL ROTARY ENCODER

摘要

PURPOSE:To correct an error in a rotational angle detection result by detecting the quantity of transmitted light in irradiation light from a light source and detecting the run-out of a rotary shaft from the run-out of a run-out detection pattern provided to a rotary disk. CONSTITUTION:When the rotary shaft 1 has a run-out, the run-out detection pattern 2b on the rotary disk 2 also has a run-out, so the quantity of the transmitted light in the irradiation light from the light source 3 varies according to the run-out of the run-out detection pattern 2b. Consequently, the output signal of a photodetection part 5 for run-out detection also varies. A run-out detection part 7 detects the variation of this output signal to detect the run-out of the rotary shaft 1. Further, the rotational angle obtained through a photodetection part 4 for angle detection and an angle detection part 6 from the transmitted light corresponding to the angle detection pattern is corrected by an arithmetic part 8 according to the run-out of the rotary shaft 1 detected by the run-out detection part 7.