Patent ID: 8295135

Claim:
An optical disc recording device for recording sub-information necessary to reproduce main information on an optical disc prerecorded with the main information by concave and convex marks, comprising: a tracking unit for controlling a position to be irradiated with laser light in accordance with a spiral track formed in a circumferential direction of the concave and convex marks; a reproduction signal extracting unit for extracting a reproduction signal from the reflected light of reproduction laser light irradiated to the concave and convex marks; a clock extracting unit for extracting a channel clock synchronized with a channel bit length of the concave and convex marks; and a sub-information recording unit for irradiating recording laser light synchronized with a band which is the integral multiple of the channel clock and lower than the band of the reproduction signal to change an optical characteristic of a reflective film formed on a recording surface of the optical disc, thereby forming a recordable mark to record the sub-information on the optical disc in a superimposition manner, wherein a width of the recordable mark in a radial direction is narrower than that of the concave and convex marks in a radial direction.