Memory disk and apparatus for recording information on memory disk

Abstract

An optical disc device includes an optical head for recording/reproducing information to and from an optical disc. The optical disc has two primary recording areas. On a first recording area of the two primary areas, the optical head records information so that the linear density of information is maintained constant. On a second recording area of the two primary areas, the optical head records information so that the spacing between adjacently recorded information increases with increasing radial position of the head or the recording position is further removed from the center of the optical disc. A substitute area is allocated such that the optical head records information in this substitute area when a defective memory portion portion is detected in the first and/or the second recording area during production or recording.