System for recovering information from a movable information storage medium having a pilot signal with an aligned phase angle in adjacent tracks
US4236050A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 30, 1978 |
| Grant date | Nov 25, 1980 |
| Priority date | — |
| Expiry date | Jun 30, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2220/20
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Method and apparatus for controlling the speed of an information storage medium, such as a disc-shaped record carrier, relative to a device for recovering information recorded thereon. The disc includes a plurality of substantially parallel information tracks arranged in a spiral or in concentric circles, and information recorded thereon includes a pilot signal having a predetermined frequency. The apparatus includes means for comparing the phase angle of the recovered pilot signal with the phase angle of a locally generated reference signal, to produce an error signal for controlling the angular velocity of a spindle motor that rotates the disc. The pilot signal includes an equal integral number of cycles on each information track, so its phase angle is aligned on adjacent tracks and the apparatus can continue to operate even when the information recovering device is traversing the disc from one track to another or is not critically positioned with respect to an individual information track.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.