Identification of non-visible faults on test CD disc surface - feeding optical signal output to detector circuit to identify changes in code to locate fault

摘要

A test signal disc (TSP) in the form of a compact disc used for checking playing equipment, is scanned by a laser head (LP) that connects with an error detecting device (FE). A start/stop circuit connects with a blending circuit (ABS). The location of the error can be fitted in a marking process in which code is generated as part of an internal process. An external marking system may be used that uses a photodetector. In both cases scratches not normally visible can be identified. ADVANTAGE - Identification of non visible scratches and faults on disc surface.