Patent ID: 6044051
Filing Date: 2000-03-28
Classification: G11B

Abstract:
An optical information recording/reproducing device for recording, reproducing, or erasing information on an optical information recording medium by radiating a light beam on the optical information recording medium,the optical information recording medium comprising information tracks formed in a spiral or concentric shape on a disk substrate, the information tracks including groove tracks and land tracks alternating with each other, each information track including:a header region for recording identification data in the form of pre-pits, the identification data representing location information on the disk substrate; and a data region for recording user data,the pre-pits being grouped into blocks each including a predetermined number of pre-pits, the blocks being disposed so as to be wobbled by a distance alternately toward an inner periphery or an outer periphery of the disk substrate along a radius direction of the disk substrate from a center line of each information track, the distance being substantially 1/2 of a track pitch of the information tracks,wherein the optical information recording/reproducing device comprises:an optical system for radiating a light beam as a converged beam spot on one of the information tracks of the optical information recording medium;an optical detector including two light receiving portions divided in parallel to the direction along which the one of the information tracks extends, the optical detector receiving the light beam reflected from the optical information recording medium;a signal generator for generating a differential signal and an addition signal of two output signals respectively output from the two light receiving portions of the optical detector;a header region detection circuit for determining whether the converged beam spot is tracing the header region or the data region based on the differential signal; andat least one reading circuit for reading the identification data from the differential signal and for reading information recorded in the data region from the addition signal;wherein the header region detection circuit includes an envelope detection circuit for detecting an envelope of the differential signal and determines that the header region is being traced when the envelope exceeds a predetermined level.