| 摘要 |
PURPOSE:To handle information for each sector by providing the header information in the form of a convex/concave pit and using independently the detection means for header and data areas respectively. CONSTITUTION:The header information is provided in the form of a pit 3 to a guide groove 2. The laser light of a semiconductor laser 4 is irradiated to the groove 2 of a disk 1 after passing through an objective lens within an AF (automatic focusing) voice coil 8. One of both reflected beams is led to a photodetector 10 for read of header part, and the other beam is led to a photodetector 13 for read of data part after conversion carried out by a photosensor 12 for the change of a polarizing angle into a change of optical intensity. For a TR (tracking) action, the detector 10 doubles a reader for the header part. Then the detection outputs divided into two parts by the detector drive a galvanomirror 7 through a TR servo circuit 14. An optical head 16 is totally moved by a linear motor 15 with a large degree of movement. In the same way, an AF action is performed by an AF servo circuit 17. |
