Compact disc cassette has an inset permanent magnetic ring that attracts a ferrous layer on disc centre for retention purposes

摘要

A compact disc, CD, [3] is located in a protective sleeve [4] and is positioned on a central spigot [41]. Attached to the disc is a thin ferrous metal disc [5] that is attracted to a permanent magnet ring [6] in the sleeve to provide secure retention. The field strength is weak enough to allow ease of separation.