Optical disc recording apparatus, optical disc recording circuit and optical disc

An optical disc recording apparatus for recording sub-information used to reproduce main information on an optical disc including concave and convex marks formed along a spiral track based on the main information and a reflective film which is formed on the concave and convex marks and whose reflectance changes upon laser light irradiation, comprising:

• an optical head for irradiating laser light to the optical disc;
• a tracking section for tracking the spiral track of the concave and convex marks;
• a reproduction signal extracting section for irradiating laser light with a first laser power to the concave and convex marks to thereby extract a reproduction signal corresponding to the concave and convex marks from reflected light;
• a clock extracting section for extracting a channel clock synchronized with a channel bit length of the concave and convex marks from the reproduction signal extracted by the reproduction signal extracting section;
• and
• a sub-information recording section for recording the sub-information by irradiating laser light with a second laser power different from the first laser power based on the tracking to the spiral track by the tracking section,
• wherein:
• the sub-information recording section records the sub-information by discretely irradiating the laser light of the second laser power at a specified interval and with a specified frequency in synchronism with the channel clock extracted by the clock extracting section by one tracking by the tracking section to form recordable marks on the reflective film;
• the specified interval is equal to or shorter than a burst error length to permit the reproduction of the main information recorded by the concave and convex marks of the optical disc;
• and
• the specified frequency is equal to or lower than a burst error frequency to permit the reproduction of the main information recorded by the concave and convex marks of the optical disc.

An optical disc, comprising:

• concave and convex marks formed in synchronism with an integral multiple of a channel bit length based on main information;
• and
• a reflective film which is formed on the concave and convex marks and whose reflectance changes upon laser light irradiation,
• wherein laser light is discretely irradiated at a specified interval and with a specified frequency in synchronism with the integral multiple of the channel bit length by one tracking based on a spiral track of the concave and convex marks formed in a circumferential direction, thereby forming a recordable mark string for recording sub-information used to reproduce the main information on the reflective film,
• the specified interval is equal to or shorter than a burst error length to permit the reproduction of the main information recorded by the concave and convex marks of the optical disc;
• and
• the specified frequency is equal to or lower than a burst error frequency to permit the reproduction of the main information recorded by the concave and convex marks of the optical disc.

An optical disc recording circuit for recording sub-information used to reproduce main information on an optical disc including concave and convex marks formed along a spiral track based on the main information and a reflective film which is formed on the concave and convex marks and whose reflectance changes upon laser light irradiation, comprising:

• a tracking controlling section for tracking the spiral track of the concave and convex marks;
• a reproduction signal processing section for irradiating laser light with a first laser power to the concave and convex marks to thereby process a reproduction signal corresponding to the concave and convex marks from reflected light;
• a clock extracting section for extracting a channel clock synchronized with a channel bit length of the concave and convex marks from the reproduction signal processed by the reproduction signal processing section;
• and
• a sub-information recording section for generating a sub-information recording signal used to record the sub-information by irradiating laser light with a second laser power different from the first laser power based on the tracking to the spiral track by the tracking controlling section,
• wherein:
• the sub-information recording section records the sub-information by discretely irradiating the laser light of the second laser power at a specified interval and with a specified frequency in synchronism with the channel clock extracted by the clock extracting section by one tracking by the tracking controlling section to form recordable marks on the reflective film,
• the specified interval is equal to or shorter than a burst error length to permit the reproduction of the main information recorded by the concave and convex marks of the optical disc;
• and
• the specified frequency is equal to or lower than a burst error frequency to permit the reproduction of the main information recorded by the concave and convex marks of the optical disc.