| 摘要 |
In an electro-magnetic actuator, an objective lens (62) is mounted on a lens holder (63) which is elastically supported by two leaf springs (64a, 64b) and a focusing coil (65) is wound around the lens holder (63). The lead springs (64a, 64b) is fixed on a carriage (66) to which tracking coil (67) is also fixed. Guide roller mechanisms (70, 71a, 71b) are provided on the both sides of the tracking coil (67) and are slidably mounted on guide rails, respectively. The tracking coil (67) are so arranged as to be extended in magnetic gaps of magnetic circuits (41-1, 41-2) disposed between the carrier (66) and the guide rails. In each of the magnetic circuit (41-1, 41-2), first and second yokes (43a-1, 43a-2, 42-1, 42-2) are so faced to each other as to defined the magnetic gap, a pair of permanent magnets (44a-1, 44a-2, 45a-1, 45a-2) are interposed between the first and second yokes (43a-1, 43a-2, 42-1, 42-2), a third yoke (43b-1, 43b-2) also so faced to the second yoke (42-1, 42-2) as to defined the magnetic gap, a pair of permanent magnets (44b-1, 44b-2, 45b-1, 45b-2) are also interposed between the second and third yokes (42-1, 42-2, 43b-1, 43b-2), and a permanent magnet (48-1, 48-2) is provide at the first yoke (43a-1, 43a-2) to apply a magnetic flux to the focusing coil (65). <IMAGE> |
