Abstract: A disk-like information recording medium includes recording areas provided in both of a groove portion and a land portion. The information recording medium is divided into groups of a plurality of areas, each track is divided into circular arc-shaped sectors having the same central angle arranged to be radial in the radius direction, identification information is provided at every sector, each track is divided into groups in such a manner that lengths of the circular arc-shaped sectors become almost constant among the groups, and the groove portion and the land portion are wobbled in the radius direction of the information recording medium. When the groove portion information track and the land portion information track which are the recording portions are wobbled in the radius direction, position information can be reliably obtained from the recording portions, and hence recorded information can be accessed reliably.

Abstract: A recording apparatus includes a recording medium, a frequency modulator for conducting frequency modulation on a digital-modulated signal to generate a recording signal, and a recording unit for recording the recording signal on the recording medium.

Abstract: A video optical disk system which can record/reproduce information in the same recording format as that of a read only type optical disk such as an LD, and is therefore compatible with both the read only type optical disk and a writable optical disk. A writable optical disk exhibiting a C/N ratio of at least 60 [dB] is employed, and has information recorded thereon with the same address signals as those of the LD and in the NTSC direct FM recording format. An optical head and an image processing circuit which are included in a player unit are made common to the recorded disk and the LD, and characteristics of a focusing/tracking control circuit, an RF signal preamplifier circuit and a tilt control circuit which are included in the player unit are changed over on the basis of reflectances of both types of optical disks, thereby enabling both the recorded disk and the LD to be reproduced.

Abstract: The present invention relates to an optical information medium for recording and reproducing information optically. Particularly, it is concerned with a so-called sample servo type optical information medium wherein an optical head traces over the center line of an imaginary track on the basis of information obtained from at least a pair of wobble pits disposed on both sides of the said imaginary track center line. A continuous groove is formed between the paired wobble pits along the imaginary track center line in a certain area of the optical information medium so that the deviation of each wobble pit from the imaginary track center line can be easily grasped and the conditions of the wobble pits being formed can be estimated. The quality of the medium being manufactured can be easily judged by the presence of such continuous groove.

Abstract: An optical disc consists of a base plate, a reflective thin layer, and a protective thin layer. The optical disc has a sample mark area having two sample marks, one of which is off-set on one side of a track, another of which is off-set at an opposite side of a track. These sample marks are produced by an injection molding with replica technique. At the time of the injection molding, additional pressure moves soft injected plastic resin, which causes double transcription of the sample marks. For preventing the double transcription, groove areas are provided on opposite sides of the sample mark area. The groove areas provide an anchor effect at the time of injection molding.