| 摘要 |
<p>An optical system (10) is provided for reading and/or recording arcuate tracks (16b) of digital information from or on a record medium (16). The system includes a rotating scanner drum (132) and a light source (38). The light source is spaced from the axis of rotation of the drum and generates an optical beam (18) having an intensity depending on whether data retrieval or recordal is desired. A lens assembly (34) including a focus and tracking lens and an objective lens is mounted on the drum and is positioned along the path of the optical beam between the light source and the record medium. Focus and tracking servo-units and actuators are disposed adjacent the lens assembly. The servo-units and actuators function to adjust the position of the focus and tracking lens axially and transversely with respect to the optical beam (18) so that the optical beam impinges on the record medium properly. An eccentricity correction function (23) is provided which adjusts the position of the record medium in the system when a track of information is to be read therefrom. The function adjusts the position of the record medium in a manner so that the arc traversed by the lens assembly (36) over the record medium aligns with the arcuate track of information to be read. This is achieved by moving the record medium so that the centre of curvature of the individual tracks recorded on the medium intersect the axis of rotation of the scanner drum.</p> |
