Absolute encoder

摘要

The present invention provides an absolute encoder including a scale on which a first mark and a second mark are arrayed, a detector configured to detect light from the scale, and to output periodic signals in which peak values, including a first peak value corresponding to the first mark and a second peak value corresponding to the second mark and smaller than the first peak value periodically appear, and a processor configured to obtain a code sequence by binarization of the first peak value and the second peak value in the periodic signals output from the detector, wherein the processor has a function of performing calibration so that the first peak value becomes larger than a threshold for the binarization and the second peak value becomes smaller than the threshold.

主权项

1. An absolute encoder comprising:
a scale on which a first mark and a second mark are arrayed; a light source configured to emit light with which the scale is irradiated; a detector configured to detect light from the scale, and to output periodic signals in which peak values, including a first peak value corresponding to the first mark and a second peak value corresponding to the second mark and smaller than the first peak value, periodically appear; and a processor configured to obtain a code sequence by binarization of the first peak value and the second peak value in the periodic signals output from the detector, wherein the processor has a function of performing calibration so that the first peak value becomes larger than a threshold for the binarization and the second peak value becomes smaller than the threshold, the processor being further configured to specify a largest first maximum value and a smallest second maximum value among maximum values of the periodic signals with regard to respective periods thereof, and set an intensity of the light emitted by the light source so that the first maximum value is not smaller than a first reference value larger than the threshold, and the second maximum value is not larger than a second reference value smaller than the threshold.