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...http://www.google.fr/patents/US3931460?utm_source=gb-gplus-shareBrevet US3931460 - Video disc with multiturn undulating storage track
Video disc with multiturn undulating storage track
