| 摘要 |
PURPOSE:To reduce the separated distance between an optical axis and the external surface of a light pickup device by arranging a tracking driving part and a focus driving part on the same line with respect to a disc and using a pair of square barlike permanent magnets as focus driving permanent magnets. CONSTITUTION:Each of a pair of focus driving permanent magnets 11 is composed of a permanent magnet piece 11A having a rectangular section, a magnetic piece 11B having an L-shaped section which is fixed on the upper surface of the permanent magnet piece 11A and a magnetic piece 11C having an L-shaped section which is fixed on the lower surface of the permanent magnetic piece 11A and a gap part 11D is formed between the magnetic pieces 11B and 11C. The focus driving permanent magnets 11 are fixed on a permanent magnet fixing board 11E so as to put a through-hole driled in the center part of the fixing board 11E between the permanent magnets 11 and the longitudinal direction of the permanent magnets 11 is in parallel with the tracking moving direction. Utilization of a pair of square barlike focus driving permanent magnets can reduce the separated distance between the optical axis and the external surface of the pickup body as compared to the cylindrical permanent magnets. |
