Machine-readable optical disc with reading-inhibit agent

Abstract From the Canadian patent

An optical disc (20), having machine-readable information-encoding features, (22) is provided with a barrier layer secured to the, disc. This barrier layer (24) is configured to prevent, machine-reading of the features. A reading-inhibit, agent (14 34), included in, the disc and activated by removal of the barrier layer, is operative once activated, to alter the disc to inhibit reading of the disc after some, period of time. Alternately the barrier layer can be, eliminated and the reading-inhibit agent can be activated by initial reading of the disc as for example by exposure to optical radiation associated with reading of the disc, or rotation of the disc.