Optical disc device, optical disc rotation position detection method, and optical disc having rotation reference mark formed as width changing in radial direction

Abstract

An optical disc device capable of detecting a reference position of an optical disc in a rotating direction includes an optical disc rotation drive unit, an optical sensor, and a control circuit. The optical disc rotation drive unit rotates the optical disc provided with a rotation reference mark. The rotation reference mark is formed into a shape having a width changing in the radial direction of the optical disc. The optical sensor detects the rotation reference mark. The control circuit controls the optical disc rotation drive unit and the optical sensor, extracts a detection signal of the rotation reference mark as a pulse waveform from an output signal of the optical sensor with the optical disc being rotated, and specifies a rotation reference position of the optical disc in accordance with the pulse waveform.