Patent ID: 8351312
Filing Date: 2013-01-08
Classification: G11B

Abstract:
1. 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; 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; the main information is composed of a plurality of frames accompanied by synchronization codes; and an equation of Lw=Lf/(2×M) (where M is a natural number) is satisfied when Lf denotes the length of the frames and Lw denotes the specified interval.