| 摘要 |
PURPOSE:To rotate a disk in an identical direction when recording or reproducing is executed on either surface by forming regulated recording tracks, which are mutually reversed with a supporting body as a symmetrical shaft, on the optical disk for both-surface recording. CONSTITUTION:When information is recorded/reproduced on/from a first recording surface 4a, the image of a laser beam from a laser 12a is formed on the recording surface of the disk 2 through a collimator lens 14a, a beam splitter 16a and an objective lens 18a. Then, the reflected light thereof retrogrades. Besides, it is passed through the splitter 16a, split by a half mirror 20a and made incident on photodetectors 22a and 24a through image forming lenses 26a and 28a. The output of the photodetector 22a is reproduced by a reproducing signal circuit 50. On the other hand, the information is recorded/reproduced on/from a second recording surface 4b by using the laser beam from a laser 12b. In such a case, since the track which is reversed with the supporting body as the symmetrical shaft is formed on the recording surface 4b, the rotating direction of the disk 2 need not be reversed. |
