Abstract: An optical information recording disk and optical information recording disk apparatus which increase the recording capacity of data recorded on the disk, and are capable of fast recording and reproduction. Logical tracks are arranged by sequentially merging physical tracks starting at the inner portion of the disk and physical tracks starting at the outer portion, and the number of sectors on corresponding tracks recorded at a constant linear density is invariably constant on the basis of the relation of arithmetical series. Consequently, the inventive system, despite of the MCAV system of constant disk speed, achieves track access and fast data transfer comparable with the conventional CAV system.

Abstract: An error detecting and correcting apparatus to detect and correct errors in code words to be subjected to a digital recording and reproducing operations by use of a recording medium. The apparatus is characterized by an interface method with respect to the host computer which generates digital information to be written on a recording medium or which utilizes the digital information read from the recording medium. The host computer supplies address data to a buffer memory circuit controlled by the error detecting and correcting apparatus through an address bus and a data bus connected between the host computer and the error detecting and correcting apparatus, thereby effecting input/output operations of digital data, namely, information codes.

Abstract: This invention relates to an optical disk, in which part of the sectors are reproduction-only sectors and remaining sectors are recording-reproduction sectors. Data and first error correcting codes for the data are recorded in advance in the reproduction-only sectors, and second error correcting codes for data over a plurality of reproduction-only sectors are recorded in advance in other reproduction-only sectors. At data reproduction, only sectors which are unrecoverable by the first error correction codes undergo error correction by the second error correcting codes, and the corrected data with the first error correcting codes being appended are recorded in the recording-reproduction sectors. Later on, when data in sectors unrecoverable by the first error correcting codes are needed, the above-mentioned recorded sectors are read out.

Abstract: In an optical information recording/reproducing apparatus for recording/reproducing information on or from an optical disc, a laser beam is focused on the surface of a substrate of the optical disc so that the intensity or a high frequency component of a reflected laser beam is used to detect contaminants on the optical disc surface or a test signal containing a plurality frequency components and recorded on a specified track on the optical disc is reproduced and detected so that the difference between amplitudes of the frequency components is used to detect contaminants on the optical disc surface. Scattering of the laser beam can be prevented and recording/reproducing can be effected with a proper level of laser power.