| 摘要 |
PURPOSE:To make it possible to detect surely the middle of audio signal groups in a reproducing device by providing access mirror face ring band and a non-signal recording track ring band in the middle of respective recording tracks of plural audio signal groups. CONSTITUTION:Plural audio signal groups are recorded on recording disc 1a so that recording tracks 2 of coaxial circles or a spiral form approximating a circle may be formed. Access mirror face ring bands 6a and 6b for optical detection of the middle of audio signal groups are formed in the middle of audio signal groups 2a-2c. Non-signal recording track ring bands 8a and 8b are provided continuously to ring bands 6a and 6b downstream in the moving direction of a contactless reproducing means. When signals reproduced from ring bands 6a and 6b are supplied to a filter to shape the waveform, a square pulse is obtained, and an arbitrary one of tracks 2a to 2c is selected by counting this pulse. Ring bands 8a and 8b are provided for synchronization restoration of reproducing of the next audio signal group. |
