DISK-TYPE DATA CARRIOER INCORPORATING TWO PORTIONS OF DIFFERENT DATE READING RATES

摘要

A disc-shaped information carrier with a substrate and an information layer which includes optically readable elementary marks having a substantially uniform density. The information layer includes a first portion suitable for being read out at a first read-out speed and a second portion suitable for being read out at a second read-out speed higher than the first read-out speed. According to the invention, the second portion of the information layer is at a greater distance to a center of the disc-shaped information carrier than is the first portion of the information layer. A range of rotational speeds which an optical read-out unit must have for a full and correct read-out of the information carrier is reduced in this manner. In a special embodiment, the first portion of the information layer includes a first version of an audio recording provided on the information layer by the DSD transformation method, whereas the second portion of the information layer includes a second version of this same audio recording provided on the information layer by the PCM transformation method.