Information recording disk having a stepped central recess and hub configuration

摘要

An information recording disk formed from two substrates with a stepped central opening for receiving a hub within the stepped recess of at least one of the substrates is provided. In one embodiment, the central aperture of the first substrate is larger than the central aperture of the second substrate to form the stepped recess. In another embodiment, at least one substrate has a stepped surface defining a central aperture and a hub structure is mounted within this stepped recess to reduce overall thickness of the disk.