| 摘要 |
PURPOSE:To record two different information while superposing them on the same track of one disc by recording one information as pit-like unevenness and the other as the change of reflection factors on a recording layer. CONSTITUTION:The recording dots of micron size are formed on recording tracks 10, 11 by changing the reflection factor of a recording thin film on the recording layer 2 under focus control and tracking control. Pits d1-dn, e1-en on the tracks 10, 11 are previously formed in a stamp process or a UV transfer process at the production of a disc. A reproduction amplifier circuit 14 detects reflected light from the disc, amplifies the detected light and inputs its output to an HPF15 and an LPF17. A signal separated by the HPF15 is inputted to a signal processing circuit 16, which decodes an information signal recorded as the change of the reflection factor of the recording layer 2. A signal separated by the LPF17 is inputted to a signal processing circuit 18, which decodes an information signal previously recorded as a pit string. |
