| 摘要 |
PURPOSE:To directly check whether the optical disk rotates normally or not by providing a rotation detecting and irradiating device and rotation detecting and photodetecting device separately from a laser light projecting device used for recording, reproducing and erasing of information. CONSTITUTION:An annular aluminum foil seal 11 printed with radial patterns at equal intervals in black is stuck to the inner side of a recording region 10 of the optical disk 1 and is used as a rotation detecting pattern. The light projected from a rotation detecting sensor 9 falls onto this annular aluminum foil when this pattern is used by being mounted to the optical disk device. The reflected light enters the photodiode of the rotation detecting sensor 9. The incident light entering the photodetecting part repeats brightening and darkening when the optical disk 1 rotates. The rotating speed of the optical disk is known by the period of this rotation. The pattern is formed of the part where the light is transmitted and the part where the light is reflected or absorbed. The rotation detecting and irradiating device 91 and the rotation detecting and photodetecting device 92 are installed on both sides of the optical disk 1. The direct checking of whether the rotation of the optical disk 1 is normal or not is thus executed. |
