Patent ID: 6946649

Claim:
A rotary encoder comprising: a disc that rotates around a rotating axis and comprises slits that are formed circumferentially at given intervals; a pair of photo-interrupters that respectively have a light-emitting device and a photo-detecting device opposite each other, and that generates two signals with a phase difference, each photo-interrupter being pivotable around a pivot coaxial to the rotating axis, and each photo-interrupter being arranged along the circumferential direction of said disc so as to position the slits between the light-emitting device and the photo-detector; an adjusting member configured to contact said pair of photo-interrupters, and configured to be movable along a shifting direction corresponding to a radial direction of said disc so as to engage said pair of photo-interrupters, said adjust member configured to adjusting a relative position-relationship between the pair of photo-interrupters associated with a phase difference; and a shifting controller configured to shift said adjusting member along the shifting direction to set the phase difference to a predetermined phase difference.