Tracking arrangement
AssigneeZenith Radio Corporation
InventorKarl H. Wossidlo
Life of this patent
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Abstract
Correction is provided for errors in radial tracking and timing in a video disc playback system of the optical type. A large ring magnet, and a smaller ring magnet carrying a mirror on one face, are coaxially aligned with the smaller magnet supported on a universal pivot and held against its support by a magnetic field. Two pairs of electromagnets, responsive to error or correction signals, cause controlled tilting of the smaller magnet about two orthogonally related axes to maintain tracking registration of a reading beam with a video disc.
Claims4
In an optical image-reproducing system in which program information stored in a generally circular track is derived by reading the track with a beam of optical energy and in which a pair of tracking correction signals is developed related to the radial tracking and timing relationships, respectively, of said beam relative to said track, an improved tracking arrangement which comprises:
- a first ring-shaped, axially poled magnet;
- a second axially-poled magnet having a pivot bearing associated therewith and poled in the same direction as said first magnet;
- support means comprising a pivot support pin mating with said pivot bearing for pivotally positioning said second magnet coaxially with and in such proximity to said first magnet as to magnetically captivate said bearing against said support pin while permitting tilting displacement of said second magnet with respect to two orthogonally related axes;
- a mirror disposed in the path of said beam and mechanically coupled to said second magnet for concurrrent displacement therewith;
- and
- a pair of electromagnetic means individually positioned along an assigned one of said axes in close proximity to said second magnet and individually responsive to an assigned one of said correction signals to develop a magnetic field, having a magnitude and direction determined by the amplitude and polarity of the applied signal, for reacting with the field of said second magnet to effect controlled displacement of said mirror with respect to the associated one of said axes.
Dependencies are inferred from the claim text.