Patent ID: 8619527

Claim:
An optical disk device for writing a recordable mark onto an optical disk having main information recorded thereon by concave-convex pits, the recordable mark being written onto the optical disk by changing a reflectance ratio of a reflective film formed on the concave-convex pits, the optical disk device comprising: an optical pickup; an RF signal processor that acquires an RF signal based on an output from the optical pickup; a reference position detector that demodulates the RF signal and detects a reference position signal; a rotation speed controller that switches a rotation speed of the optical disk between at least two rotation speeds; an emission timing generation unit that generates, according to the reference position signal, an emission timing at which a laser beam is radiated from the optical pickup at a predetermined position; a laser power controller that increases a laser power of the laser beam that is radiated from the optical pickup at the emission timing; a reflectance ratio change amount detector that detects, from the RF signal, an amount of change in a reflectance ratio of reflected light reflected from the optical disk; a concave-convex pit reproduction controller that sets a first rotation speed in the rotation speed controller and a first laser power in the laser power controller when reproducing the concave-convex pits formed on the optical disk, the concave-convex pits recording the main information on the optical disk; and a recordable mark recording controller that, when writing the recordable mark onto the optical disk, changes the reflectance ratio of the reflective film formed on the concave-convex pits by setting (i) the rotation speed controller, a second rotation speed that is slower than the first rotation speed and a lowest rotation speed at which the concave-convex pits can be reproduced and (ii) a second laser power greater than the first laser power in the laser power controller according to the emission timing.