Record carrier on which information is stored in an optically readable structure
ApplicationNo. 05/810702 filed on 06/28/1977
US Classes:369/93, SYSTEMS HAVING PLURAL PHYSICALLY DISTINCT INDEPENDENT TRACKS ON A SINGLE STORAGE MEDIUM SURFACE365/124, Diffraction369/102, Multiplex369/108, Color369/109.02, Plural elements with distinct diffractive characteristics369/111, Spiral or helical track369/275.3, Track data format/layout369/275.4Pit/bubble/groove structure specifies
ExaminersPrimary: Cardillo, Raymond F. Jr.
Attorney, Agent or Firm
International ClassesG11B 7/00 (20060101)
G11B 7/005 (20060101)
AbstractA video recording disk that is optically readable has data represented in a form that permits data track revolutions to be spaced close together without an intervening guardband or with only a narrow guardband. The track revolutions are in two sets that form a parallel spiral or alternating concentric circles so that a track revolution of one set is separated from other track revolutions of the same set by intervening track revolutions of the other set. Binary data is represented on the tracks by deformations or the absence of deformations, and the record is read as destructive interference in a light beam produced at the location of a deformation. Deformations of the first set of tracks have a depth that is appropriate to be read with a wavelength designated lambda 1, and deformations of the second set have a depth to be read by light of a wavelength lambda 2. Light that is reflected from an adjacent track does not have any significant data content, and the track revolutions can be located close together without producing significant interference in the signals.