198138 ⎘
Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation , reproducing using an optical beam at lower power ; Record carriers therefor; Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the form of the carrier; Cards intended for rotation
Optical disc device, optical disc rotation position detection method, and optical disc having rotation reference mark formed as width changing in radial direction
#2Disk-shaped information recording medium, disk cartridge and information recording and reproducing apparatus
#3Disk-shaped information recording medium, disk cartridge, and information recording/reproducing apparatus