Disc recording and/or reproducing apparatus for permitting continuous

Abstract

A disc recording and/or reproducing apparatus for recording and/or reproducing information signals on or from an optical disc on which there is formed a spirally extending recording track is disclosed. The apparatus includes fundamental clock generating circuits for generating fundamental clocks CK.sub.A and CK.sub.B having different frequencies associated with recording regions E.sub.A and E.sub.B of different recording densities formed on the optical disc, and a clock changeover circuit for making a changeover between the fundamental clocks CK.sub.A and CK.sub.B from the fundamental clock generating circuits based on the boundary position information between the recording regions E.sub.A and E.sub.B. During transition from a first recording region of a first recording density to a second recording region of a second recording density, the clocks from the clock generating circuit are changed over instantly to the fundamental clock associated with the second recording region to enable plural recording regions with different recording densities to be processed continuously.