| 摘要 |
PURPOSE:To cope with the variability of an optical disk by dividing and providing a reproducing exclusive area in which the synchronous reproduction can be executed by recording two kinds of different existing information, and an additional recording area in which the symultaneous recording and reproduction can be executed by varying the positions of two kinds of different information. CONSTITUTION:In a reproducing exclusive area, on the surface of a substrate 30, two lines of signal marks derived from two kinds of different information, that is, lines of small holes 32, 33 of two lines form a pair, and formed spirally at a minute distance to an adjacent pair of lines. In an additional recording area, on a substrate 40, a shallow groove whose cross section is rectangular, what is called a guide groove is provided spirally at a minute distance. On its surface, in the incident direction of a light beam, in other words, in this side seen from the opposite surface side of the surface on which the guide groove is provided, a first recording medium film 41, and subsequently, a second recording medium film 42 are laminated successively in this order, and different information is recorded in every layer. According to such a structure, two kinds of light beams whose wavelength is different are used for recording and reproducing the information, and also, by using an optical head for discriminating, separating and synthesizing its light beam, it is possible to meet a customer's taste and expectation. |
