| 摘要 |
PURPOSE:To obtain easily stable read information by having different structures between tracking and focusing magnetic circuit systems and positioning a tracking coil at the neutral point of a magnetic flux of a magnet. CONSTITUTION:An inside yoke 33, a ring magnet 34 and an outside yoke 35 constitute a magnetic circuit system for focus control which shifts a lens holding arm 37 in the thrust direction. While an outside yoke 25, a magnet 26 and an inside yoke 36 constitute a magnetic circuit system for tracking control which revolves the arm 37 around a support shaft 29. Furthermore, a screw is unfastened to move a control plate 27 and a holding stage 19. Thus a coil 45 and the yoke 36 can be positioned at the center of the magnetic flux of a magnet 26. Therefore, the stable read information is easily obtained with no high accuracy of parts. |
