Video disc with multiturn undulating storage track
US3931460A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 4, 1974 |
| Grant date | Jan 6, 1976 |
| Priority date | — |
| Expiry date | Feb 4, 1994 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B23/0057
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A video disc has a storage track formed of half wavelength pits alternating with lands. The track has a series of turns, individually of a generally circular path but undulating symmetrically about that path. The undulations of the several turns have such relative phase that the turns are in nested concentric relation and one component of the stored information represents the phase of the undulations. The record is a replication of a master formed under the control of a laser writing beam modulated with the information to be stored. A Bragg cell in the optical path, responding to a cyclic frequency-modulated signal, optically displaces the writing beam about a reference path to develop undulations in the record storage track.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.