| 摘要 |
PURPOSE:To reduce a noise and to shorten an initializing time by simultaneously erasing a recording track and a guide track with using an erasing beam whose spot diameter is large. CONSTITUTION:A bias coil 13 to form an erase magnetic field is provided in the upper direction of a magnetic disk 1 which has a guide channel 2 and a recording track 3. Then, in a condition that the erase magnetic field is formed by a current in this coil 13, both semiconductor lasers 4 and 8 are emitted. An output light 1 of this laser 4 is condensed through a deflecting beam splitter 6 and a diaphragm lens 7 on a magneto-optical recording disk 1 and a spot L is formed. The reflected light of this disk 1 is successively passed through the lens 7, the splitter 6, a filter 10 and a diaphragm lens 11, converted to an electric signal by an optical detector 12 and sent to an automatic focusing/ tracking actuator 14. A light (m) from the laser 8 is condensed on the disk 1 samely as the light 1 and a spot M, whose beam diameter is larger than a track pitch width, is formed. Then, the recording track and guide track are simultaneously erased with using the erase beam of the large diameter. |
