Optical disk device, optical disk control method, and integrated circuit

An integrated circuit provided in 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 integrated circuit comprising:
• an RF signal processing circuit that acquires an RF signal based on an output from an optical pickup;
• a reference position detecting circuit that demodulates the RF signal and detects a reference position signal;
• a rotation speed control circuit that switches a rotation speed of the optical disk between at least two rotation speeds;
• an emission timing generating circuit 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 control circuit 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 detecting circuit 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 control circuit that sets a first rotation speed in the rotation speed control circuit and a first laser power in the laser power control circuit 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 control circuit 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 control circuit, 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 control circuit according to the emission timing.

An optical disk control method 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 control method comprising:
• an RF signal processing step of acquiring an RF signal based on an output from an optical pickup;
• a reference position detection step of demodulating the RF signal and detecting a reference position signal;
• a rotation speed controlling step of switching a rotation speed of the optical disk between at least two rotation speeds;
• an emission timing generation step of generating, 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 controlling step of increasing a laser power of the laser beam that is radiated from the optical pickup at the emission timing;
• a reflectance ratio change amount detection step of detecting, 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 controlling step of setting a first rotation speed in the rotation speed controlling step and a first laser power in the laser power controlling step 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 record controlling step of, 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 controlling step, 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 controlling step according to the emission timing.